                  FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

MARIA M. GONZALEZ,; LUCIANO             
VALENCIA; THE INTER TRIBAL
COUNCIL OF ARIZONA, INC.;
ARIZONA ADVOCACY NETWORK;
STEVE M. GALLARDO; LEAGUE OF
UNITED LATIN AMERICAN CITIZENS
ARIZONA; LEAGUE OF WOMEN
VOTERS OF ARIZONA;
PEOPLE FOR THE AMERICAN WAY
FOUNDATION; HOPI TRIBE,
                          Plaintiffs,   
               and
BERNIE ABEYTIA; ARIZONA HISPANIC
COMMUNITY FORUM; CHICANOS POR
LA CAUSA; FRIENDLY HOUSE; JESUS
GONZALEZ; DEBBIE LOPEZ;
SOUTHWEST VOTER REGISTRATION
EDUCATION PROJECT; VALLE DEL
SOL; PROJECT VOTE,
             Plaintiffs- Appellants,
                                        




                            17617
17618              GONZALEZ v. ARIZONA


                                     
                 v.
STATE OF ARIZONA; JAN BREWER, in
her official capacity as Secretary
of State of Arizona; SHELLY
BAKER, La Paz County Recorder;
BERTA MANUZ, Greenlee County
Recorder; CANDACE OWENS,
Coconino County Recorder; LYNN
CONSTABLE, Yavapai County
Election Director; KELLY DASTRUP,
Navajo County Election Director;
LAURA DEAN-LYTLE, Pinal County
Recorder; JUDY DICKERSON,
Graham County Election Director;
DONNA HALE, La Paz County            
Election Director; SUSAN
HIGHTOWER MARLAR, Yuma County
Recorder; GILBERTO HOYOS, Pinal
County Election Director;
LAURETTE JUSTMAN, Navajo County
Recorder; PATTY HANSEN,
Coconino County Election
Director; CHRISTINE RHODES,
Cochise County Recorder; LINDA
HAUGHT ORTEGA, Gila County
Recorder; DIXIE MUNDY, Gila
County Election Director; BRAD
NELSON, Pima County Election
Director; KAREN OSBORNE,
Maricopa County Election
Director;
                                     
                    GONZALEZ v. ARIZONA               17619



YVONNE PEARSON, Greenlee County       
Election Director; PENNY PEW,                No. 08-17094
Apache County Election Director;               D.C. Nos.
HELEN PURCELL, Maricopa County            2:06-cv-01268-ROS
Recorder; F. ANN RODRIGUEZ, Pima
County Recorder,
                                          06-cv-01362-PCT-
                                                  JAT
             Defendants-Appellees,        06-cv-01575-PHX-
YES ON PROPOSITION 200,                          EHC
    Defendant-intervenor-Appellee,
                                      

MARIA M. GONZALEZ; BERNIE             
ABEYTIA; ARIZONA HISPANIC
COMMUNITY FORUM; CHICANOS POR
LA CAUSA; FRIENDLY HOUSE; JESUS
GONZALEZ; DEBBIE LOPEZ;
                                      
SOUTHWEST VOTER REGISTRATION
EDUCATION PROJECT; LUCIANO
VALENCIA; VALLE DEL SOL;
PEOPLE FOR THE AMERICAN WAY
FOUNDATION; PROJECT VOTE,
                        Plaintiffs,
               and
                                      
17620               GONZALEZ v. ARIZONA



THE INTER TRIBAL COUNCIL OF            
ARIZONA, INC.; ARIZONA ADVOCACY
NETWORK; STEVE M. GALLARDO;
LEAGUE OF UNITED LATIN AMERICAN
CITIZENS ARIZONA; LEAGUE OF
WOMEN VOTERS OF ARIZONA; HOPI
TRIBE,
              Plaintiffs-Appellants,
                 v.
STATE OF ARIZONA; JAN BREWER, in
her official capacity as Secretary
of State of Arizona; SHELLY
BAKER, La Paz County Recorder;
BERTA MANUZ, Greenlee County
Recorder; CANDACE OWENS,               
Coconino County Recorder; PATTY
HANSEN, Coconino County
Election Director; KELLY DASTRUP,
Navajo County Election Director;
LYNN CONSTABLE, Yavapai County
Election Director; LAURA DEAN-
LYTLE, Pinal County Recorder;
JUDY DICKERSON, Graham County
Election Director; DONNA HALE,
La Paz County Election Director;
SUSAN HIGHTOWER MARLAR, Yuma
County Recorder; GILBERTO
HOYOS, Pinal County Election
Director;
                                       
                   GONZALEZ v. ARIZONA                17621



LAURETTE JUSTMAN, Navajo County      
Recorder; CHRISTINE RHODES,
Cochise County Recorder; LINDA
HAUGHT ORTEGA, Gila County
Recorder; DIXIE MUNDY, Gila
County Election Director; BRAD
NELSON, Pima County Election
Director; KAREN OSBORNE,                    No. 08-17115
Maricopa County Election
Director; YVONNE PEARSON,
Greenlee County Election
                                             D.C. No.
                                         2:06-cv-01268-ROS
Director; PENNY PEW, Apache                   OPINION
County Election Director; HELEN
PURCELL, Maricopa County
Recorder; F. ANN RODRIGUEZ, Pima
County Recorder,
             Defendants-Appellees,
YES ON PROPOSITION 200,
    Defendant-intervenor-Appellee.
                                     
       Appeal from the United States District Court
                for the District of Arizona
        Roslyn O. Silver, District Judge, Presiding

                 Argued and Submitted
           October 20, 2009—Tucson, Arizona

                  Filed October 26, 2010
17622                   GONZALEZ v. ARIZONA
    Before: Sandra Day O’Connor, Associate Justice,*
  Alex Kozinski, Chief Judge, and Sandra S. Ikuta, Circuit
                          Judge.

                    Opinion by Judge Ikuta;
                Dissent by Chief Judge Kozinski




   *The Honorable Sandra Day O’Connor, Associate Justice of the United
States Supreme Court (Ret.), sitting by designation pursuant to 28 U.S.C.
§ 294(a).
17628               GONZALEZ v. ARIZONA




                         COUNSEL

Nina Perales, Mexican American Legal Defense and Educa-
tion Fund, San Antonio, Texas, for Plaintiffs/Appellants Jesus
M. Gonzalez, et al.

Jon M. Greenbaum, Lawyers Committee for Civil Rights
Under Law, Washington, D.C., for Plaintiffs/Appellants Inter
Tribal Council, et al.

Karen J. Hartman-Tellez, Phoenix, Arizona, for Plain-
tiffs/Appellants Inter-Tribal Council, et al.

Barbara A. Bailey, Assistant Attorney General, Phoenix, Ari-
zona, for Defendants/Appellees State of Arizona and Arizona
Secretary of State Ken Bennett.
                   GONZALEZ v. ARIZONA               17629
Mary R. O’Grady, Solicitor General, Phoenix, Arizona, for
Defendants/Appellees State of Arizona and Arizona Secretary
of State Ken Bennett.

Dennis Wilenchik, Wilenchik and Bartness, P.C., Phoenix,
Arizona, for Defendants/Appellees Shelly Baker, La Paz
County Recorder, et al.

Sam Hirsch, Jenner & Block LLP, Washington, D.C., on
behalf of Amicus Curiae The League of Women Voters of the
United States.

Kali N. Bracey, Jenner & Block LLP, Washington, D.C., on
behalf of Amicus Curiae The League of Women Voters of the
United States.

Jessica Ring Amunson, Jenner & Block LLP, Washington,
D.C., on behalf of Amicus Curiae The League of Women
Voters of the United States.

Barnaby W. Zall, Weinberg & Jacobs, LLP, Rockville, Mary-
land, on behalf of Amicus Curiae American Unity Legal
Defense Fund, Inc.

Charles E. Borden, O’Melveny & Myers LLP, Washington,
D.C., on behalf of Amicus Curiae National Association of
Latino Elected and Appointed Officials Educational Fund.

Joel M. Spector, Mountain States Legal Foundation, Lake-
wood, Colorado, on behalf of Amicus Curiae Mountain States
Legal Foundation.

Michael J. Reitz, Evergreen Freedom Foundation, Olympia,
Washington, on behalf of Amicus Curiae Evergreen Freedom
Foundation.

Brian D. Netter, Mayer Brown LLP, Washington, D.C., on
behalf of Amici Curiae Congressman Robert A. Brady, Con-
17630                 GONZALEZ v. ARIZONA
gresswoman Zoe Lofgren, Congressman Charles A. Gonza-
lez, Congressman Raul M. Grijalva, and Congressman Jose E.
Serrano.

Richard A. Samp, Washington Legal Foundation, Washing-
ton, D.C., on behalf of Amici Curiae Protect Arizona Now,
Washington Legal Foundation, and Allied Educational Foun-
dation.


                           OPINION

IKUTA, Circuit Judge:

   Proposition 200 requires prospective voters in Arizona to
present documentary proof of citizenship in order to register
to vote, Ariz. Rev. Stat. §§ 16-152, 16-166, and requires reg-
istered voters to present proof of identification in order to cast
a ballot at the polls, Ariz. Rev. Stat. § 16-159. This appeal
raises the questions whether Proposition 200 violates the Vot-
ing Rights Act § 2, 42 U.S.C. § 1973, is unconstitutional
under the Fourteenth or Twenty-fourth Amendments of the
Constitution, or is void as inconsistent with the National
Voter Registration Act (NVRA), 42 U.S.C. § 1973gg et seq.
We hold that the NVRA supersedes Proposition 200’s voter
registration procedures, and that Arizona’s documentary proof
of citizenship requirement for registration is therefore invalid.
We reject the remainder of Appellants’ arguments.

                                I

   On November 2, 2004, Arizona voters passed a state initia-
tive, Proposition 200, which (upon proclamation of the Gov-
ernor) enacted various revisions to the state’s election laws.
Among other changes, Proposition 200 amended the proce-
dures for voter registration and for checking voters’ identifi-
cation at polling places in both state and federal elections.
                           GONZALEZ v. ARIZONA                          17631
With respect to voter registration procedures, Proposition 200
amended two state statutes. First, it added the following
requirement to section 16-152 of the Arizona Revised stat-
utes, which lists the contents of the state voter registration
form:

       The form used for the registration of electors shall
       contain . . . [a] statement that the applicant shall sub-
       mit evidence of United States citizenship with the
       application and that the registrar shall reject the
       application if no evidence of citizenship is attached.

Ariz. Rev. Stat. § 16-152(A)(23). Second, it amended section
16-166 of the Arizona Revised statutes to state that: “The
County Recorder shall reject any application for registration
that is not accompanied by satisfactory evidence of United
States citizenship,” and defined satisfactory evidence of citi-
zenship to include a driver’s license or similar identification
license issued by a motor vehicle agency, a birth certificate,
passport, naturalization documents or other specified immi-
gration documents, or specified cards relating to Native
American tribal status. See Ariz. Rev. Stat. § 16-166(F).1
  1
    Section 16-166(F) provides the following list of approved identifica-
tion documents:
      1. The number of the applicant’s driver license or nonoperating
      identification license issued after October 1, 1996 by the depart-
      ment of transportation or the equivalent governmental agency of
      another state within the United States if the agency indicates on
      the applicant’s driver license or nonoperating identification
      license that the person has provided satisfactory proof of United
      States citizenship.
      2. A legible photocopy of the applicant’s birth certificate that ver-
      ifies citizenship to the satisfaction of the county recorder.
      3. A legible photocopy of pertinent pages of the applicant’s
      United States passport identifying the applicant and the appli-
      cant’s passport number or presentation to the county recorder of
      the applicant’s United States passport.
17632                   GONZALEZ v. ARIZONA
   Proposition 200 also addressed identification procedures at
polling places. Specifically, Proposition 200 amended section
16-579 of the Arizona Revised Statutes to provide that voters
“shall present one form of identification that bears the name,
address and photograph of the elector or two different forms
of identification that bear the name and address of the elec-
tor.” Ariz. Rev. Stat. § 16-579(A) (2004). The Secretary of
State, acting under statutory authority, see Ariz. Rev. Stat.
§ 16-452(A), (B), promulgated a procedure specifying the
“forms of identification” accepted under the statute, which
included photograph-bearing documents such as driver’s
licenses and non-photograph-bearing documents such as util-
ity bills or bank statements. In 2009, the state legislature
amended section 16-579 to codify that procedure.2

   4. A presentation to the county recorder of the applicant’s United
   States naturalization documents or the number of the certificate
   of naturalization. If only the number of the certificate of natural-
   ization is provided, the applicant shall not be included in the reg-
   istration rolls until the number of the certificate of naturalization
   is verified with the United States immigration and naturalization
   service by the county recorder.
   5. Other documents or methods of proof that are established pur-
   suant to the immigration reform and control act of 1986.
     6. The applicant’s Bureau of Indian Affairs card number, tribal
     treaty card number or tribal enrollment number.
  2
    As of 2009, section 16-579(A)(1) provides:
   (a) A valid form of identification that bears the photograph, name
   and address of the elector that reasonably appears to be the same
   as the name and address of the precinct register, including an Ari-
   zona driver license, an Arizona nonoperating identification
   license, a tribal enrollment card or other form of tribal identifica-
   tion or a United States federal, state or local government issued
   identification. Identification is deemed valid unless it can be
   determined on its face that it has expired.
   (b) Two different items that contain the name and address of the
   elector that reasonably appears to be the same as the name and
   address in the precinct register, including a utility bill, a bank or
                         GONZALEZ v. ARIZONA                        17633
   Shortly after Proposition 200’s passage, various plaintiffs
filed a complaint against Arizona to prevent the implementa-
tion of these changes. Two groups of plaintiffs are relevant to
this appeal. Jesus Gonzalez, representing individual Arizona
residents and organizational plaintiffs, claimed that Proposi-
tion 200 violated the NVRA (to the extent the Arizona enact-
ment regulated federal registration procedures), was a poll tax
under the Twenty-fourth Amendment, burdened naturalized
citizens in violation of the Equal Protection Clause of the
Fourteenth Amendment, and disparately impacted Latino vot-
ers and diluted Latino voting power in violation of § 2 of the
Voting Rights Act. The Inter Tribal Council of Arizona
(ITCA), a non-profit organization representing twenty Ari-
zona tribes, filed a complaint along with various other organiza-
tions,3 the Hopi Tribe, and Representative Steve Gallardo
from the Arizona State House of Representatives.4 Like Gon-

    credit union statement that is dated within ninety days of the date
    of the election, a valid Arizona vehicle registration, an Arizona
    vehicle insurance card, Indian census card, tribal enrollment card
    or other form of tribal identification, a property tax statement, a
    recorder’s certificate, a voter registration card, a valid United
    States federal, state or local government issued identification or
    any mailing that is “official election material.” Identification is
    deemed valid unless it can be determined on its face that it has
    expired.
      (c) A valid form of identification that bears the photograph, name
      and address of the elector except that if the address on the identi-
      fication does not reasonably appear to be the same as the address
      in the precinct register or the identification is a valid United
      States Military identification card or a valid United States pass-
      port and does not bear an address, the identification must be
      accompanied by one of the items listed in subdivision (b) of this
      paragraph.
   3
     ITCA’s action was joined by the League of Women Voters of Arizona,
the League of United Latin American Citizens, the Arizona Advocacy
Network, and People For the American Way Foundation, as well as the
claimants listed above.
   4
     We refer to named plaintiffs Gonzalez and ITCA as representing all
plaintiffs associated in their respective actions. Where appropriate, we
17634                   GONZALEZ v. ARIZONA
zalez, ITCA claimed that Proposition 200 violated the NVRA
(to the extent it regulated federal registration procedures), and
constituted a poll tax under the Twenty-fourth Amendment.
ITCA also separately claimed that Proposition 200 was a poll
tax under the Fourteenth Amendment. The district court con-
solidated Gonzalez and ITCA’s complaints.

   Gonzalez and ITCA moved for a preliminary injunction to
enjoin application of Proposition 200’s requirements in the
2006 general election, Gonzalez v. Arizona (Gonzalez I), 485
F.3d 1041, 1047 (9th Cir. 2007). The district court denied
their motion, but a motions panel of this court reversed and
granted the injunction pending disposition of the merits on
appeal. Id. The Supreme Court vacated the injunction, and
remanded for clarification whether this court had given due
deference to the district court’s findings of fact. Id. at 1048;
see Purcell v. Gonzalez, 549 U.S. 1, 5 (2006). On remand,
Gonzalez and ITCA chose to pursue injunctive relief with
respect only to Proposition 200’s registration requirement.
Gonzalez I, 485 F.3d at 1048. The Gonzalez I panel thereafter
affirmed the district court’s denial of the preliminary injunc-
tion, holding that Proposition 200’s registration requirement
was not a poll tax, id. at 1049, and was not a violation of the
NVRA, id. at 1050-51. The district court subsequently
granted Arizona’s motion for summary judgment, relying on
Gonzalez I to rule that Proposition 200 was not an unconstitu-
tional poll tax and was not invalid as conflicting with the
NVRA. After trial, the district court resolved all other claims
in favor of Arizona, holding that Proposition 200 did not vio-
late § 2 of the Voting Rights Act and did not discriminate
against naturalized citizens or burden the fundamental right to

refer to Gonzalez and ITCA individually; however, because Gonzalez and
ITCA bring the same NVRA and Twenty-fourth Amendment claims, we
refer to both collectively as “Gonzalez” in the sections discussing these
two claims. We refer to the defendants collectively as “Arizona,” even
though Arizona county recorders were also named as defendants in these
consolidated actions.
                     GONZALEZ v. ARIZONA                  17635
vote in violation of the Fourteenth Amendment’s Equal Pro-
tection Clause.

   On appeal, Gonzalez and ITCA challenge the district
court’s rulings on the NVRA and the Twenty-fourth Amend-
ment. In addition, ITCA claims that Proposition 200 is an
invalid poll tax under the Fourteenth Amendment, and Gonza-
lez challenges the district court’s decisions on both the Voting
Rights Act claim and the equal protection challenge for dis-
crimination based on national origin and undue burden on the
fundamental right to vote. We consider each of these claims
in turn.

                               II

   We begin with Gonzalez’s claim that Proposition 200’s
documentary proof of citizenship requirement for registration
is superseded by the NVRA’s comprehensive procedure for
registering voters in federal elections. Gonzalez argues that
the NVRA preempts Arizona law under both the Supremacy
Clause and the Elections Clause of the U.S. Constitution. In
response, Arizona relies on the Supremacy Clause’s “pre-
sumption against preemption,” Medtronic, Inc. v. Lohr, 518
U.S. 470, 485 (1996), to argue that the NVRA did not
expressly or impliedly preempt state voter registration laws.
Before addressing the parties’ arguments, we first consider
whether the framework of the Elections Clause or the
Supremacy Clause guides our analysis here.

                               A

  [1] The Elections Clause establishes a unique relationship
between the state and federal governments. It provides:

    The Times, Places, and Manner of holding Elections
    for Senators and Representatives, shall be prescribed
    in each State by the Legislature thereof; but Con-
    gress may at any time by Law make or alter such
17636                      GONZALEZ v. ARIZONA
      Regulations, except as to the Place of chusing Sena-
      tors.

U.S. Const. art, I, § 4, cl. 1. In a nutshell, the Elections Clause
gives state governments initial responsibility to regulate the
mechanics of national elections, “but only so far as Congress
declines to preempt state legislative choices.” Foster v. Love,
522 U.S. 67, 69 (1997).

   The history of the Elections Clause reveals the reasoning
behind this unusual delegation of power. Under the Articles
of Confederation, the states had full authority to maintain,
appoint, or recall congressional delegates.5 At the Philadel-
phia Convention, delegates expressed concern that, if left
unfettered, states could use this power to frustrate the creation
of the national government, most obviously by neglecting to
hold federal elections.6 The Framers decided that Congress
should be given the authority to oversee the states’ procedures
related to national elections as a safeguard against potential
state abuse. See U.S. Term Limits, Inc. v. Thornton, 514 U.S.
779, 808-09 (1995); see also The Federalist No. 59 (Alexan-
der Hamilton) (Ron P. Fairfield 1981 ed., 2d ed.) (explaining
that “[n]othing can be more evident, than that an exclusive
power of regulating elections for the national government, in
the hands of the State legislatures, would leave the existence
of the Union entirely at their mercy”). Over the protest of
  5
     See Articles of Confederation of 1781, art. V (“[D]elegates shall be
annually appointed in such manner as the legislature of each state shall
direct . . . with a power, reserved to each state, to recall its delegates . . . .
Each state shall maintain its own delegates in a meeting of the states
. . . .”).
   6
      See 1 The Debates in the Several State Conventions on the Adoption
of the Federal Constitution as Recommended by the General Convention
at Philadelphia in 1787 Together with the Journal of the Federal Conven-
tion, Luther Martin’s Letter, Yates’s Minutes, Congressional Opinions,
Virginia & Kentucky Resolutions of ’98-’99, and Other Illustrations of the
Constitution 225 (photo. reprint 1987) (Jonathan Elliot ed., 2d ed. 1901)
[hereinafter Elliot’s Debates].
                         GONZALEZ v. ARIZONA                         17637
some Southern delegates,7 the Framers approved language
giving Congress power to “make or alter” the states’ regula-
tions. See 5 Elliot’s Debates 401-02 (statement of James Mad-
ison). As subsequently modified to give Congress supervisory
power, this language became the Elections Clause.8

   As indicated by this historical context, the Elections Clause
empowers both the federal and state governments to enact
laws governing the mechanics of federal elections. By its
plain language, the Clause delegates default authority to the
states to prescribe the “Times, Places, and Manner” of con-
ducting national elections in the first instance. U.S. Const. art.
I, § 4, cl. 1. The states would not possess this authority but for
the Clause: As the Supreme Court has noted, the authority to
regulate national elections “aris[es] from the Constitution
itself,” and is therefore “not a reserved power of the States.”
U.S. Term Limits, 514 U.S. at 805. Because federal elections
did not come into being until the federal government was
formed, individual states have no inherent or preexisting
authority over this domain. See d. at 804-05.

   While the states have default responsibility over the
mechanics of federal elections, because Congress “may at any
time by Law make or alter such Regulations” passed by the
state, U.S. Const. art. I, § 4, cl. 1, power over federal election
  7
     South Carolinian delegates Charles Pinckney and John Rutledge
moved to exclude the language giving Congress this supervisory power
over the states. 5 Elliot’s Debates at 401. “The states, they contended,
could and must be relied on” to regulate legislative appointments. Id. See
also Vieth v. Jubelirer, 541 U.S. 267, 275-76 (2004).
   8
     Alexander Hamilton described the need for congressional oversight of
the states as follows: “[The Framers] have submitted the regulation of
elections for the federal government, in the first instance, to the local
administrations; which, in ordinary cases, and when no improper views
prevail, may be both more convenient and more satisfactory; but they have
reserved to the national authority a right to interpose, whenever extraordi-
nary circumstances might render that interposition necessary to its safety.”
The Federalist No. 59.
17638                    GONZALEZ v. ARIZONA
procedures has been described by the Supreme Court as ulti-
mately “committed to the exclusive control of Congress.”
Colgrove v. Green, 328 U.S. 549, 554 (1946).9 Accordingly,
“the power of Congress over the subject is paramount. It may
be exercised as and when Congress sees fit to exercise it.
When exercised, the action of Congress, so far as it extends
and conflicts with the regulations of the State, necessarily
supersedes them.” Ex Parte Siebold, 100 U.S. 371, 384
(1879); see also Foster, 522 U.S. at 69.

   Not only does the Elections Clause grant Congress author-
ity to supersede state election laws, but we have interpreted
the Clause to require states to affirmatively implement Con-
gress’s superseding regulations, without compensation from
the federal government. Voting Rights Coalition v. Wilson, 60
F.3d 1411, 1415 (9th Cir. 1995). Put another way, the Elec-
tions Clause gives Congress the power to “conscript state
agencies to carry out [federal] voter” procedures in accor-
dance with Congress’s own mandates. Id. This makes the
Clause unique among virtually all other provisions in the
Constitution, which “mostly tell [states] not what they must
do but what they can or cannot do.” ACORN v. Edgar, 56
F.3d 791, 794 (7th Cir. 1995).

   [2] In sum, a state’s role in the creation and implementa-
tion of federal election procedures under the Elections Clause
   9
     The Court has generally construed Congress’s exclusive authority
under the Elections Clause expansively. See, e.g., United States v. Gra-
dwell, 243 U.S. 476, 483 (1917) (authority over federal election process,
from registration to certification of results); United States v. Mosley, 238
U.S. 383, 386 (1915) (authority to enforce the right of an eligible voter to
cast ballot and have ballot counted); Ex Parte Coy, 127 U.S. 731, 752-53
(1888) (authority to regulate conduct at any election coinciding with fed-
eral contest); Ex parte Yarbrough (The Ku Klux Cases), 110 U.S. 651, 662
(1884) (authority to make additional laws for free, pure, and safe exercise
of right to vote); Ex parte Clarke, 100 U.S. 399, 404 (1879) (authority to
punish state election officers for violation of state duties vis-a-vis Con-
gressional elections).
                      GONZALEZ v. ARIZONA                  17639
is to administer the elections through its own procedures until
Congress deems otherwise; if and when Congress acts, the
states are obligated to conform to and carry out whatever pro-
cedures Congress requires. See Foster, 522 U.S. at 69.

   As should be clear from this overview, the Elections Clause
operates quite differently from the Supremacy Clause. The
Supremacy Clause provides that the law of the United States
“shall be the supreme Law of the Land; . . . any Thing in the
Constitution or Laws of any state to the Contrary notwith-
standing.” U.S. Const. art. VI, cl. 2. “The primary function of
the Supremacy Clause is to define the relationship between
state and federal law. It is essentially a power conferring pro-
vision, one that allocates authority between the national and
state governments.” White Mountain Apache Tribe v. Wil-
liams, 810 F.2d 844, 848 (9th Cir. 1985).

   [3] In our system of dual sovereignty, when deciding under
the Supremacy Clause whether a particular state law is pre-
empted by a federal enactment, courts strive to maintain the
“delicate balance” between the States and the Federal Govern-
ment. Gregory v. Ashcroft, 501 U.S. 452, 460 (1991); see
Medtronic, 518 U.S. at 485. Courts thus endeavor to preserve
the states’ authority when possible, see Gregory, 501 U.S. at
460, particularly where a congressional enactment threatens to
preempt a state law regulating matters of its residents’ health
and safety, an area to which “[s]tates traditionally have had
great latitude . . . to legislate” as a matter of local concern,
Metro. Life Ins. Co. v. Massachusetts, 471 U.S. 724, 756
(1985). See also Altria Group, Inc. v. Good, 129 S. Ct. 538,
543 (2008); Medtronic, 518 U.S. at 485. Only where no rec-
onciliation between state and federal enactments may be
reached do courts hold that Congress’s enactments must pre-
vail, e.g., Altria, 129 S. Ct. at 543, with the understanding,
however, that “the individual States . . . retain [their] indepen-
dent and uncontrollable authority . . . to any extent” that Con-
gress has not interfered, see The Federalist No. 33 (Alexander
Hamilton).
17640                GONZALEZ v. ARIZONA
   In light of the different history and purpose of these consti-
tutional provisions, it is not surprising that the preemption
analysis for the Supremacy Clause differs from that of the
Elections Clause. In its Supremacy Clause jurisprudence, the
Supreme Court has crafted special guidelines to assist courts
in striking the correct balance between federal and state
power. First, in examining claims that a federal law preempts
a state statute through the Supremacy Clause, the Supreme
Court instructs courts to begin with a “presumption against
preemption.” E.g., Altria Group, 129 S. Ct. at 543; Medtronic,
518 U.S. at 485. This principle applies because, as the Court
has recently noted, “respect for the States as independent sov-
ereigns in our federal system leads us to assume that Congress
does not cavalierly pre-empt state-law causes of action.”
Wyeth v. Levine, 129 S. Ct. 1187, 1195 n.3 (2009) (internal
quotation marks omitted). Second, the Court has adopted a
“plain statement rule,” holding that a federal statute preempts
a state statute only when it is the “clear and manifest purpose
of Congress” to do so. Gregory, 501 U.S. at 461 (internal
quotation marks omitted); see also Cipollone v. Liggett
Group, Inc., 505 U.S. 504, 516 (1992) (“Consideration of
issues arising under the Supremacy Clause starts with the
assumption that the historic police powers of the States are
not to be superseded by . . . Federal Act, unless that is the
clear and manifest purpose of Congress.”) (internal quotation
marks and brackets omitted)). Like the presumption against
preemption, this rule “is nothing more than an acknowledg-
ment that the States retain substantial sovereign powers under
our constitutional scheme, powers with which Congress does
not readily interfere.” Gregory, 501 U.S. at 461.

   [4] This jurisprudence, which is motivated in large part by
federalism concerns, is unsuited to analyzing the preemptive
effect of a congressional enactment under the Elections
Clause. Because the states’ sole power over national election
procedures is that delegated by the Elections Clause, U.S.
Term Limits, 514 U.S. at 805, and states otherwise have no
reserved authority over this domain, id., courts deciding
                     GONZALEZ v. ARIZONA                  17641
issues raised under the Elections Clause need not strike any
balance between competing sovereigns. Instead, the Elections
Clause, as a standalone preemption provision, establishes its
own balance, resolving all conflicts in favor of the federal
government. See, e.g., Foster, 522 U.S. at 71 (stating that “the
Constitution explicitly gives Congress the final say” on mat-
ters related to federal election procedures). For this reason,
the “presumption against preemption” and “plain statement
rule” that guide courts’ analysis of preemption under the
Supremacy Clause are not transferable to the Elections Clause
context. Cf. Gregory, 501 U.S. at 460-61. Indeed, the
Supreme Court has suggested as much. In Foster, the Court
upheld the Fifth Circuit’s determination that a state election
law was voided by a federal election law; however, instead of
adopting the Fifth Circuit’s Supremacy Clause analysis, the
Supreme Court analyzed the claim under the Elections
Clause, without ever mentioning any presumption against pre-
emption or requirement of a plain statement of congressional
intent to preempt. See Foster, 522 U.S. 67; Love v. Foster, 90
F.3d 1026 (5th Cir. 1996), cert. granted in 522 U.S. 67. In
fact, our survey of Supreme Court opinions deciding issues
under the Elections Clause reveals no case where the Court
relied on or even discussed Supremacy Clause principles.

   [5] Because the Elections Clause empowered Congress to
enact the NVRA, Wilson, 60 F.3d at 1414, the preemption
analysis under that Clause is applicable here. We begin our
analysis as the Court did in Foster, guided by Election Clause
preemption principles. Accord Harkless v. Brunner, 545 F.3d
445, 454 (6th Cir. 2008) (declining to apply Supremacy
Clause preemption principles in analyzing the preemptive
effect of the NVRA).

                               B

   The Supreme Court first explained the principles of Elec-
tions Clause preemption in Siebold, 100 U.S. 371. In that
case, the Court likened the relationship between the laws
17642                GONZALEZ v. ARIZONA
passed by Congress and the state legislatures under the Elec-
tions Clause to “prior and subsequent enactments of the same
legislature.” Id. at 384. “The State laws which Congress sees
no occasion to alter, but which it allows to stand, are in effect
adopted by Congress.” Id. at 388. By this token, just as a sub-
sequent legislature is not required to make an “entirely new
set” of laws when modifying those of a prior legislature, nei-
ther is Congress required to wholly take over the regulation
of federal election procedures when choosing to “make or
alter” certain of the states’ rules. Id. at 384. According to the
Court, there is no “intrinsic difficulty in such co-operation”
between the state and national legislatures because the two
governments do not possess an “equality of jurisdiction” with
respect to federal elections. Id. at 392. While Congress may
override state enactments, the state may not vitiate an action
of Congress by adopting a system of regulations to undo con-
gressional efforts. See id. at 393, 397. In all instances, “the
laws of the State, in so far as they are inconsistent with the
laws of Congress on the same subject, cease to have effect as
laws.” Id. at 397.

   Over a century later, the Supreme Court clarified what con-
stitutes a conflict under the Elections Clause’s single system
of federal election procedures. See Foster, 522 U.S. 67. Fos-
ter considered whether a congressional enactment superseded
a Louisiana statute regulating the same federal election proce-
dure. Id. at 68-69. Specifically, sections 1 and 7 of Title 7 of
the U.S. Code established the date for federal congressional
elections as the Tuesday after the first Monday in November.
Id. at 69-70. A Louisiana statute established an open primary
in October where state voters could elect the candidate who
would fill the offices of United States Senator and Represen-
tative. Id. at 70. Only if the open primary failed to result in
a majority candidate would a run off election between the top
two candidates be held on Congress’s specified election day.
Id. In response to a challenge by Louisiana voters, the Court
unanimously held that the state and federal acts conflicted,
and thus invalidated the Louisiana law. Id. at 74.
                     GONZALEZ v. ARIZONA                   17643
   In concluding that Congress’s power to preclude the state
statute was beyond argument, the Court rejected the state’s
claim that its statute and the federal enactment could be con-
strued harmoniously. Id. at 73. Louisiana asserted that “the
open primary system concern[ed] only the ‘manner’ of elect-
ing federal officials, not the ‘time’ at which the elections will
take place.” Id. at 72. The Court discarded this “attempt to
draw this time-manner line” as “merely wordplay” and an
“imaginative characterization” of the statutes. Id. at 72-73.
Building upon the principles from Siebold, the Court declined
to adopt a strained interpretation of the statutes to reconcile a
potential disagreement. See id. Rather, the Court emphasized
Congress’s unique plenary authority not only to supplant state
rules but to conscript states to carry out federal enactments
under the Elections Clause, and found it enough that, under a
natural reading, the state and federal enactments addressed the
same procedures and were in conflict. Id. (noting that the
Louisiana’s regulation addressed the timing of elections
“quite as obviously” as the federal one). Refusing to “par[e]
[the statute] down to the definitional bone,” the Court held
that the state enactment was void. Id. at 72, 74.

   [6] Reading Siebold and Foster together, we derive the fol-
lowing approach for considering whether federal enactments
under the Elections Clause displace a state’s procedures for
conducting federal elections. First, as suggested in Siebold,
we consider the state and federal laws as if they comprise a
single system of federal election procedures. Siebold, 100
U.S. at 384. If the state law complements the congressional
procedural scheme, we treat it as if it were adopted by Con-
gress as part of that scheme. See id. If Congress addressed the
same subject as the state law, we consider whether the federal
act has superseded the state act, based on a natural reading of
the two laws and viewing the federal act as if it were a subse-
quent enactment by the same legislature. Foster, 522 U.S. at
74. With this approach in mind, we consider whether the
NVRA and Proposition 200 operate harmoniously in a single
procedural scheme for federal voter registration.
17644                   GONZALEZ v. ARIZONA
                                   C

   To resolve the question here, we must first understand both
the federal and state voter registration procedures at issue. We
earlier explained the changes to Arizona’s registration statutes
under Proposition 200, which incorporated a requirement that
registrants submit documentary proof of citizenship in order
to register to vote. See supra Part I; Ariz. Rev. Stat. §§ 16-
152, 16-166. Our next step is to examine the scope of the
NVRA.

                                   1

   Congress enacted the NVRA because, among other rea-
sons, it determined that “discriminatory and unfair registration
laws and procedures can have a direct and damaging effect on
voter participation in elections for Federal office and dispro-
portionately harm voter participation by various groups,
including racial minorities.” 42 U.S.C. § 1973gg(a).

   Initially, Congress attempted to address this problem by
enacting legislation that permitted the government and pro-
spective voters to challenge discriminatory practices in the
courts. See South Carolina v. Katzenbach, 383 U.S. 301, 313
(1966) (discussing the Civil Rights Act of 1957, which “au-
thorized the Attorney General to seek injunctions against pub-
lic and private interference with the right to vote on racial
grounds,” and the Civil Rights Act of 1964, which “expedited
the hearing of voting cases before three-judge courts and out-
lawed some of the tactics” used to disqualify African Ameri-
cans from voting in federal elections).10 The elimination of
discriminatory voting practices through litigation, however,
was “slow and expensive, and [meanwhile] the States were
creative in contriving new rules to continue violating the Fif-
  10
    Neither of these Acts were passed under the substantive authority of
the Elections Clause, and therefore the Elections Clause analysis is not
applicable to cases considering these enactments.
                     GONZALEZ v. ARIZONA                   17645
teenth [and Fourteenth] Amendment[s] in the face of adverse
federal court decrees.” Nw. Austin. Mun. Utility Dis. No. One
v. Holder (NAMUDNO), 129 S. Ct. 2504, 2508-09 (2009)
(internal quotations marks omitted). To limit voter registra-
tion, some local officials defied court edicts or “simply closed
their registration offices to freeze the voting rolls.” Katzen-
bach, 383 U.S. at 314. Congress’s attempts to “authoriz[e]
registration by federal officers . . . had little impact on local
maladministration.” Id. Nearly a century after the Civil War,
registration of eligible African American voters in some states
was still fifty percentage points lower than that of eligible
white voters. Shaw v. Reno, 509 U.S. 630, 640 (1993).

   Congress tried a different approach to addressing this prob-
lem by passing the Voting Rights Act of 1965 (VRA), Pub.
L. No. 89-110, 79 Stat. 437 (codified at 42 U.S.C. § 1973 et
seq.). The VRA, enacted under the authority of Congress’s
Fifteenth Amendment enforcement powers, is “a complex
scheme of stringent remedies aimed at areas where voting dis-
crimination has been most flagrant.” Katzenbach, 383 U.S. at
308, 315. As enacted, the VRA suspended the use of literacy
tests, § 4(a)-(d), required covered jurisdictions to pre-clear
changes in voting procedures and practices, § 5, and provided
for the appointment of federal examiners to assist in register-
ing qualified citizens to vote, §§ 6, 7, 9, 13. Section 2 of the
VRA also permits actions to be brought to void voting qualifi-
cations or prerequisites “resulting in the denial or abridgement
of the right of any citizen of the United States to vote on
account or race or color.”

   [7] While considered on the whole to be a successful tool
in eliminating the more obvious discriminatory voting proce-
dures, see NAMUDNO, 129 S.Ct. at 2511, the VRA failed to
address voter registration procedures, which imposed a “com-
plicated maze of local laws and procedures, in some cases as
restrictive as the out-lawed practices, through which eligible
citizens had to navigate in order to exercise their right to
vote,” H.R. Rep. No. 103-9, at 3 (1993). Between 1988 and
17646                 GONZALEZ v. ARIZONA
1993, Congress held a series of hearings focused on reforming
the voter registration process to address the increasingly
pressing issue of low voter turnout in federal elections. Con-
don v. Reno, 913 F. Supp. 946, 949 n.2 (D.S.C. 1995). Con-
gress found that, while over eighty percent of registered
citizens voted in Presidential elections, only sixty percent of
eligible voters were registered. H.R. Rep. No. 103-9, at 3.
Public opinion polls showed that the primary reason eligible
citizens were not voting was the failure to register. Id. While
acknowledging that this failure was attributable to many fac-
tors outside its control, Congress enacted the NVRA to
address the problems within its control, namely those barriers
to registration that were imposed by state governments. See
id. Under the Elections Clause, Congress had the power “to
provide a complete code for congressional elections, not only
as to times and places, but in relation to . . . registration.” Smi-
ley v. Holm, 285 U.S. 355, 366 (1932). Through this author-
ity, Congress enacted the NVRA to remove these obstacles
and “to provide simplified systems for registering to vote in
federal elections.” Young v. Fordice, 520 U.S. 273, 275
(1997) (emphasis omitted).

                                 2

   The NVRA is a comprehensive scheme enacting three sig-
nificant changes to federal election registration procedures
nationwide: (1) it creates a standard “Federal Form”
(described below) for registering federal voters; (2) it requires
states to establish procedures to register voters for federal
elections according to three prescribed methods; and (3) it
regulates maintenance of voting lists. See 42 U.S.C. § 1973gg
et seq.

  Section 1973gg, setting forth the act’s “Findings and Pur-
poses,” provides an overview of the NVRA. The “findings”
subsection, § 1973gg(a), articulates Congress’s intent to pro-
mote voter registration and to address “discriminatory and
unfair registration laws.” The “purposes” subsection,
                          GONZALEZ v. ARIZONA                    17647
§ 1973gg(b), provides a preview of the operative sections of
the NVRA, listing Congress’s goals of increasing voter regis-
tration and enhancing the participation of eligible voters
(relating to Sections 2 through 5, § 1973gg-2-§ 1973gg-5) and
the goals of ensuring the accuracy of registration rolls and
protecting the integrity of the electoral process (relating to
Section 6, § 1973gg-6).

  Section 2, § 1973gg-2, sets forth the scope and applicability
of the act.11 Each state (except for those that do not require
voter registration as a prerequisite to voting) “shall establish
procedures to register” voters for federal elections according
to the NVRA’s three methods “notwithstanding any other
Federal or State law, in addition to any other method of voter
registration provided for under State law.” § 1973gg-2(a).

   The first method of voter registration is described in Sec-
tion 3, § 1973gg-3. This section provides that any application
for a driver’s license submitted to a state motor vehicle
authority “shall serve as an application for voter registration
with respect to elections for Federal office unless the appli-
cant fails to sign the voter registration application.” § 1973gg-
3(a)(1). This provision earned the statute its informal title, the
“Motor Voter Law.” United States v. Lara, 181 F.3d 183, 191
(1st Cir. 1999). Under the statute, the voter registration form
must be part of the driver’s license application, and generally
“may not require any information that duplicates information
required in the driver’s license portion of the form.”
§ 1973gg-3(c)(2)(A). Section 3 also limits the content of the
form to the minimum necessary to prevent duplicate voter
registrations and to enable the state to assess the eligibility of
the applicant.12
  11
    Section 1 of the NVRA defines terms used in the statute. § 1973gg-1.
  12
    Section 1973gg-3(c) provides, in pertinent part:
       The combined motor vehicle-voter registration form:
       (B) may require only the minimum amount of information neces-
       sary to—
17648                   GONZALEZ v. ARIZONA
   The second method of voter registration, set forth in Sec-
tion 4, § 1973gg-4, requires states to register federal voters by
mail using the Federal Form. Section 4(a)(1) states that
“[e]ach State shall accept and use the [Federal Form] for the
registration of voters in elections for Federal office.” Section
4(a)(2) provides that, “[i]n addition to accepting and using
[the Federal Form], a State may develop and use a mail voter
registration form that meets all the criteria” of the Federal
Form. Section 4(b) discusses the availability of the Federal
Form and the state equivalent: States must make the mail reg-
istration form “available for distribution through governmen-
tal and private entities, with particular emphasis on making
them available for organized voter registration programs.”
§ 1973gg-4(b). With certain exceptions not pertinent here, the
statute permits states to require citizens who register by mail
to vote in person if they have not previously voted in the juris-
diction. § 1973gg-4(c).

   The third method of federal voter registration is mandated
by Section 5, § 1973gg-5, which requires states to designate
certain state offices for voter registration. Targeting “the poor
and persons with disabilities who do not have driver’s
licenses and will not come into contact with” motor vehicle
agencies, H.R. Rep. No. 103-55, at 19 (1993), as reprinted in
1993 U.S.C.C.A.N. 140, 144, this section requires states to

   (I) prevent duplicative voter registrations; and
   (ii) enable State election officials to assess the eligibility of the
   applicant and to administer voter registration and other parts of
   the election process;
   (C) shall include a statement that—
   (I) states each eligibility requirement (including citizenship)
   (ii) contains an attestation that the applicant meets each such
   requirement; and
   (iii) requires the signature of the applicant under penalty of perju-
   ry[.]
                       GONZALEZ v. ARIZONA                     17649
provide for federal registration at “all offices in the State that
provide public assistance,” § 1973gg-5(a)(2)(A), and “all
offices in the State that provide State-funded programs pri-
marily engaged in providing services to persons with disabili-
ties,” § 1973gg-5(a)(2)(B). The state may also designate
additional government offices such as “public libraries, public
schools, offices of city and county clerks (including marriage
license bureaus), fishing and hunting license bureaus, govern-
ment revenue offices, unemployment compensation offices,
and [other offices] that provides services to persons with dis-
abilities” as voter registration agencies. § 1973gg-5(a)(3).

   Section 5 requires each designated agency to provide appli-
cants with the Federal Form, help them complete it, and man-
dates “[a]cceptance of completed voter registration
application forms for transmittal to the appropriate State elec-
tion official.” § 1973gg-5(a)(4)(A). As in Section 4, the desig-
nated state agency may also distribute a state form, but only
“if it is equivalent” to the Federal Form. § 1973gg-
5(a)(6)(A)(ii).

   Section 6, § 1973gg-6, establishes procedures to enhance
the accuracy and integrity of the official voting lists both by
removing ineligible voters and preventing the mistaken
removal of eligible voters.

   Section 7, § 1973gg-7, describes how the federal and state
governments will determine the contents of the Federal Form,
and otherwise coordinate administration of the NVRA’s pro-
cedures. This section delegates the creation of the Federal
Form to the federal Election Assistance Commission (EAC).13
§ 1973gg-7(a). The section requires the EAC to work “in con-
  13
    The responsibilities of the EAC were formerly held by the Federal
Election Commission (FEC). When Congress passed the Help America
Vote Act (HAVA), Pub. L. No. 107-252, 116 Stat. 1666, in 2002, it cre-
ated the EAC, 42 U.S.C. § 15321, which eventually absorbed the FEC’s
duties under the NVRA.
17650                        GONZALEZ v. ARIZONA
sultation with the chief election officers of the States” in craft-
ing the Form’s contents. Id.

   Section 7 also sets out parameters for what the Federal
Form may, shall, and cannot include.14 Among other things,
the Federal Form “may require only such identifying informa-
tion” as is necessary to allow the state to determine the eligi-
bility of the applicant and to administer the voter registration
and election process. § 1973gg-7(b)(1). The Federal Form
  14
    The Federal Form:
       (1) may require only such identifying information (including the
       signature of the applicant) and other information (including data
       relating to previous registration by the applicant), as is necessary
       to enable the appropriate State election official to assess the eligi-
       bility of the applicant and to administer voter registration and
       other parts of the election process;
       (2) shall include a statement that—
       (A) specifies each eligibility requirement (including citizenship);
       (B) contains an attestation that the applicant meets each such
       requirement; and
       (C) requires the signature of the applicant, under penalty of per-
       jury;
       (3) may not include any requirement for notarization or other for-
       mal authentication; and
       (4) shall include, in print that is identical to that used in the attes-
       tation portion of the application—
       (I) [voter eligibility requirements and penalties for false applica-
       tions, § 1973gg-6(a)(5)]
       (ii) a statement that, if an applicant declines to register to vote,
       the fact that the applicant has declined to register will remain
       confidential and will be used only for voter registration purposes;
       and
       (iii) a statement that if an applicant does not register to vote, the
       office at which the applicant submits a voter registration applica-
       tion will remain confidential and will be used only for voter reg-
       istration purposes.
§ 1973gg-7(b).
                     GONZALEZ v. ARIZONA                   17651
must inform the applicant as to every eligibility requirement
“including citizenship” and require the applicant to attest,
under penalty of perjury, that the applicant meets each
requirement. § 1973gg-7(b)(2). The form “may not include
any requirement for notarization or other formal authentica-
tion.” § 1973gg-7(b)(3).

   Section 8, § 1973gg-8, requires states to designate an offi-
cer to serve as chief election official. Section 9, § 1973gg-9,
regulates civil enforcement of the NVRA’s provisions and
designates a private right of action under the statute. Section
10, § 1973gg-10, sets forth the criminal penalties for election
fraud or other non-compliance with the statute.

   As this overview indicates, the thrust of the NVRA is to
increase federal voter registration by streamlining the registra-
tion process. In this vein, the NVRA requires states to make
registration opportunities widely available, at the motor vehi-
cle bureau, § 1973gg-3, by mail, § 1973gg-4, and at public
assistance, disability service, and other designated state
offices, § 1973gg-5. Along with increasing the opportunities
for registration, the NVRA eases the burdens of completing
registration forms. At the motor vehicle authority, for
instance, voter registration must be included as part of the
driver’s license application and the combined form cannot
require duplicative information. § 1973gg-3(c)(2)(A). The
NVRA also regulates the Federal Form to meet its goal of
eliminating      obstacles    to    voter    registration.    See
§ 1973gg(b)(1)-(2). Thus, the NVRA forbids the EAC from
including any identifying information beyond that “necessary
to enable the appropriate State election official to assess the
eligibility of the applicant and to administer voter registration
and other parts of the election process.” § 1973gg-7(b)(1). In
sum, as every court to have considered the act has concluded,
the NVRA’s central purpose is to increase voter registration
by streamlining voter registration procedures. See, e.g., Hark-
less, 545 F.3d at 449; Welker v. Clarke, 239 F.3d 596, 598-99
(3d Cir. 2001) (“One of the NVRA’s central purposes was to
17652                 GONZALEZ v. ARIZONA
dramatically expand opportunities for voter registration
. . . .”); Disabled in Action of Metro. N.Y. v. Hammons, 202
F.3d 110, 114 (2d Cir. 2000); Lara, 181 F.3d at 192 (“The
NVRA is addressed to heightening overall popular participa-
tion in federal elections . . . .”); Nat’l Coal. for Students with
Disabilities Educ. & Legal Def. Fund v. Allen, 152 F.3d 283,
285 (4th Cir. 1998) (“Congress passed the NVRA . . . to
encourage increased voter registration for elections involving
federal offices” and “to make it easier to register to vote.”);
ACORN v. Miller, 129 F.3d 833, 835 (6th Cir. 1997) (“In an
attempt to reinforce the right of qualified citizens to vote by
reducing the restrictive nature of voter registration require-
ments, Congress passed the [NVRA].”).

                                3

   Turning now to our Elections Clause analysis, we consider
whether Proposition 200’s documentary proof of citizenship
requirement is superseded by the NVRA. As indicated by the
approach derived from Siebold and Foster, see supra Part
II.B, we consider the state and federal enactments together as
if they composed a single system of federal election proce-
dures. Next, we consider whether, read naturally, the NVRA
provisions complement Proposition 200’s voter registration
requirements or supersede them. If a natural interpretation of
the language of the two enactments leads to the conclusion
that the state law does not function consistently and harmoni-
ously with the overriding federal scheme, then it is replaced
by the federal statute.

   [8] Applying this framework, we conclude that Proposition
200’s documentary proof of citizenship requirement conflicts
with the NVRA’s text, structure, and purpose. First, the
NVRA addresses precisely the same topic as Proposition 200
in greater specificity, namely, the information that will be
required to ensure that an applicant is eligible to vote in fed-
eral elections. See Foster, 522 U.S. at 73. Section 7 of the
NVRA, § 1973gg-7, both spells out the information that an
                      GONZALEZ v. ARIZONA                   17653
applicant must provide in order to register to vote in a federal
election and limits what the Federal Form can require. It “may
require only such identifying information (including the sig-
nature of the applicant) and other information (including data
relating to previous registration by the applicant), as is neces-
sary to enable the appropriate State election official to assess
the eligibility of the applicant.” § 1973gg-7(b)(1). The Federal
Form accounts for eligibility concerns by requiring applicants
to attest, under penalty of perjury, that they meet every eligi-
bility requirement. § 1973gg-7(b)(2). Acknowledging the
states’ interests in ensuring voter eligibility, Congress allowed
states to give their input on the contents of the Federal Form
in an advisory capacity to the EAC. § 1973gg-7(a)(2). Given
the NVRA’s comprehensive regulation of the development of
the Federal Form, there is no room for Arizona to impose sua
sponte an additional identification requirement as a prerequi-
site to federal voter registration for registrants using that form.
If viewed as a second enactment by the same legislature, the
NVRA clearly subsumes Proposition 200’s additional docu-
mentary requirement on registrants using the Federal Form.
See Siebold, 100 U.S. at 384.

   [9] Further supporting this conclusion, the value of the
Federal Form (and hence a centerpiece of the NVRA) would
be lost, and Congress’s goal to eliminate states’ discrimina-
tory or onerous registration requirements vitiated, if we were
to agree with Arizona that states could add any requirements
they saw fit to registration for federal elections through the
Federal Form. For instance, the NVRA prohibits the Federal
Form from requiring notarization or other such formal authen-
tication. § 1973gg-7(b)(3). If the NVRA did not supersede
additional state requirements on registrants using the Federal
Form, as Arizona asserts, then states would be free to impose
a notarization requirement as a prerequisite to their “accept-
[ance] and use” of the form, see § 1973gg-4(a)(1), even
though such a requirement would directly contradict Con-
gress’s intent in prohibiting such a requirement in the form
itself.
17654                GONZALEZ v. ARIZONA
   [10] Moreover, specific statutory language in the NVRA,
when read in an unstrained and natural manner, is inconsistent
with the state enactment. The NVRA mandates that states
“shall accept and use” the Federal Form when applicants reg-
ister by mail. § 1973gg-4(a). It likewise requires “acceptance”
of the completed Federal Form at state office buildings, which
must be transmitted to the appropriate State election officials.
§ 1973gg-5(a)(4)(iii). The state must implement these meth-
ods of registering voters, as well as the combined motor
vehicle-voter registration form, § 1973gg-3(c)(1), “notwith-
standing any other Federal or state law,” § 1973gg-2(a). By
contrast, Proposition 200 precludes the state from registering
applicants who have completed and submitted the Federal
Form unless such applicants also mail in, or submit at the des-
ignated state office building, documentary proof of citizen-
ship. Ariz. Rev. Stat. §§ 16-152, 16-166. Such a requirement
falls under the umbrella of laws displaced by the NVRA’s
“notwithstanding” language.

   Structurally, allowing states to impose their own require-
ments for federal voter registration on registrants using the
Federal Form would nullify the NVRA’s procedure for solic-
iting state input, and aggrandize the states’ role in direct con-
travention of the lines of authority prescribed by Section 7.
The NVRA permits states to suggest changes to the Federal
Form, but gives the EAC ultimate authority to adopt or reject
those suggestions. § 1973gg-7(a). Here, for example, before
enacting Proposition 200, Arizona petitioned the EAC to
include a requirement in the Federal Form that the applicant
present documentary proof of citizenship analogous to what
is required by Proposition 200. Pursuant to the procedure set
forth in the NVRA, the EAC denied the suggestion and
warned that Arizona “may not refuse to register individuals to
vote in a Federal election for failing to provide supplemental
proof of citizenship, if they have properly completed and
timely submitted the Federal Registration Form.” Faced with
this denial, Arizona proceeded to implement the requirement
in Proposition 200 as a separate state condition to voter regis-
                     GONZALEZ v. ARIZONA                  17655
tration, which was imposed even on those registering to vote
in federal elections with the Federal Form. If the NVRA did
not supersede state-imposed requirements for federal voter
registration, this type of end-run around the EAC’s consulta-
tive process would become the norm, and Congress’s control
over the requirements of federal registration would be crip-
pled. Given that the Elections Clause gives Congress ultimate
authority over the federal voter registration process, Colgrove,
328 U.S. at 554, such a reading of the NVRA is untenable.

   [11] More broadly, Proposition 200 is not in harmony with
the intent behind the NVRA, which is to reduce state-imposed
obstacles to federal registration. It is indisputable that by
requiring documentary proof of citizenship, Proposition 200
creates an additional state hurdle to registration. As indicated
in our overview, supra Part C.2, the NVRA was sensitive to
the multiple purposes of a federal voter registration scheme,
including the need “to establish procedures that [would]
increase the number of eligible citizens who register to vote
in elections for Federal office” and the need to protect “the
integrity of the electoral process.” § 1973gg(b). The balance
struck by the EAC pursuant to § 1973gg-7(a) was to require
applicants to attest to their citizenship under penalty of per-
jury, but not to require the presentation of documentary proof.
Id. Proposition 200’s additional requirement is not consistent
with this balance.

   Arizona argues that Proposition 200 does not conflict with
the NVRA because the NVRA nowhere expressly precludes
states from imposing requirements in addition to those of the
Federal Form. Focusing on the phrase in the NVRA Section
4 which requires states to “accept and use” the Federal Form
to register mail applicants, see § 1973gg-4(a)(1), Arizona
argues that its registration process complies with the NVRA
because the state makes the Federal Form available to appli-
cants, and will accept the Form so long as it is accompanied
by documentary proof of citizenship.
17656                     GONZALEZ v. ARIZONA
   [12] Like the petitioners in Foster, Arizona has offered a
creative interpretation of the state and federal statutes to avoid
a direct conflict. See Foster, 522 U.S. at 72. But as Foster
counsels, we do not strain to reconcile the state’s federal elec-
tion regulations with those of Congress under the Elections
Clause; rather, we consider whether the additional registration
requirement mandated by Proposition 200 is harmonious with
the procedures mandated by Congress under a natural reading
of the statutes. See id. at 74; Siebold, 100 U.S. at 384. As
explained above, allowing Arizona to impose Proposition
200’s registration provisions on top of the Federal Form con-
flicts with the NVRA’s purpose, procedural framework, and
the specific requirement that states use the Federal Form or its
equivalent, “notwithstanding any other state or federal law,”
§ 1973gg-2(a). Under Congress’s expansive Elections Clause
power, we must hold Arizona’s documentary proof of citizen-
ship requirement, Ariz. Rev. Stat. §§ 16-152(A)(23), 16-
166(F), superseded by the NVRA.15

                                     4

   Arizona’s remaining arguments do not persuade us to reach
  15
     Because we reach our conclusion based on the language and structure
of the statute, we do not rely on the EAC’s interpretation of the NVRA
or the NVRA’s legislative history. Because the parties argue the import of
these sources, we merely note that both are consistent with our holding.
As discussed supra page 17654, the EAC construes the NVRA as not per-
mitting states to “condition acceptance of the Federal Form upon receipt
of additional proof.” With respect to legislative history, the NVRA’s Con-
ference Report, which we have held is the most authoritative and reliable
legislative material, see, e.g., Nw. Forest Res. Council v. Glickman, 82
F.3d 825, 835 (9th Cir. 1996), shows that Congress rejected an amend-
ment to the NVRA which would have provided that “nothing in this Act
shall prevent a State from requiring presentation of documentation relating
to citizenship of an applicant for voter registration,” H.R. Rep. No. 103-
66, at 23 (1993). The conferees explained that the amendment was not
“consistent with the purposes of” the NVRA and “could effectively elimi-
nate, or seriously interfere with, the mail registration program of the Act.”
Id.
                     GONZALEZ v. ARIZONA                  17657
a different conclusion. First, Arizona contends that an inter-
pretation of the NVRA that precludes states from imposing
additional voter registration requirements for federal elections
is unreasonable because Congress could not have intended
states to register “any and all” applicants who submit the Fed-
eral Form without any outlet for the states to check those
applicants’ qualifications. Arizona asserts that because the act
contemplates that some applications will be rejected, see
§ 1973gg-6(a)(2) (which requires states to notify “each appli-
cant of the disposition of the application”), the NVRA cannot
require states to automatically register every individual using
the Federal Form.

   This argument reflects a misunderstanding of the NVRA.
As Section 6 demonstrates, states need not register every
applicant who completes and submits the Federal Form. See
§ 1973gg-6(a)(2). Voters still have to prove their eligibility
pursuant to the Federal Form. Contrary to Arizona’s assertion,
the NVRA does not require states to register applicants who
are ineligible, or whose forms are incomplete, inaccurate, or
illegible.

   Second, Arizona argues that states must have freedom to
exercise their own methods for determining voter eligibility as
a protection against voter fraud. In ACORN v. Edgar, the Sev-
enth Circuit considered and discarded a similar argument. In
that case, the state claimed that the “Motor Voter” component
of the NVRA “opens the door to voter fraud.” 56 F.3d at 795.
The court rejected the argument in part because “federal law
contains a number of safeguards against vote fraud, and it is
entirely conjectural that they are inferior to the protections
that [state] law offers.” Id. at 795-96 (citation omitted).

   We reach the same conclusion here. Congress was well
aware of the problem of voter fraud when it passed the
NVRA, as evidenced by the numerous fraud protections built
into the act. For one, Section 10 applies federal criminal pen-
alties to persons who knowingly and willingly engage in
17658                GONZALEZ v. ARIZONA
fraudulent registration tactics. § 1973gg-10(2). Second, Sec-
tions 3 and 7 require the Federal Form and the combined
motor vehicle-voter registration form to contain an attestation
clause that sets out the requirements for voter eligibility.
§§ 1973gg-3(c)(2)(C)(i)-(ii), 1973gg- 7(b)(2)(A)-(B). Appli-
cants are required to sign these forms under penalty of per-
jury. §§ 1973gg-3(c)(2)(C)(iii), 1973gg-7(b)(2)(C). Third,
Section 4 permits states to verify the eligibility and identity
of voters by requiring first-time voters who register by mail
to appear at the polling place in person, where the voter’s
identity can be confirmed. § 1973gg-4(c). Last, Section 6
requires states to give notice to applicants of the disposition
of their registration, which states may use as a means to detect
fraudulent registrations. See § 1973gg-6(a)(2). Because Con-
gress dealt with the issue of voter fraud in the NVRA, we are
not persuaded by Arizona’s claim that states must be permit-
ted to impose additional requirements to address the same
issue.

   Third, Arizona suggests that Congress’s enactment of
HAVA, 42 U.S.C. § 15301 et seq., which Congress passed
after the NVRA, provides a gloss on the NVRA’s meaning.
According to Arizona, HAVA demonstrated Congress’s intent
to permit states to ensure the eligibility of voter registrants,
and made clear that states could exceed the minimum require-
ments of the NVRA in carrying out their registration func-
tions.

   We disagree. Congress enacted HAVA in reaction to the
2000 Presidential election and the ensuing controversial Flor-
ida recount. Fla. State Conference of NAACP v. Browning,
522 F.3d 1153, 1155 (11th Cir. 2008). The NVRA and HAVA
operate in separate spheres: while the NVRA regulates voter
registration, HAVA is concerned with updating election tech-
nologies and other election-day issues at polling places.

   As relevant here, HAVA interacts with the NVRA only on
a few discrete issues. First, HAVA added two check-boxes to
                      GONZALEZ v. ARIZONA                   17659
the Federal Form, requiring applicants to check off whether
they are citizens of the United States and whether they are old
enough to vote. 42 U.S.C. § 15483(b)(4).

   Second, HAVA permits mail registrants who have not pre-
viously voted in a federal election to submit documents veri-
fying their identity along with the Federal Form.
§ 15483(b)(3). First-time voters who take advantage of this
provision do not have to show their identification when they
arrive at the polling place, id., a step that the states may other-
wise require under the NVRA, see § 1973gg-4(c). This option
is not, however, a prerequisite to successful registration, as
applicants who choose not to submit documentation may still
be registered.

   Third, HAVA requires states to assign each registrant a
“unique identifier” capable of being cross-checked against
voters’ identities at the polls. § 15483(a)(1)(A). HAVA pro-
vides that the unique identifier may be the applicant’s driver’s
license number or the last four digits of the applicant’s social
security number. See § 15483(a)(5)(A). But nothing in HAVA
allows the state to require these forms of identification as a
prerequisite to registration. Rather, if the applicant possesses
neither a driver’s license nor social security card, HAVA
requires the state to assign the applicant “a number which will
serve to identify the applicant for voter registration purposes.”
§ 15483(a)(5)(A)(ii). The unique identifier is not used to
check the citizenship of the registrant, but rather to ensure that
the voter who appears at the polls is the same person who reg-
istered to vote.

   Nor does HAVA allow states to exceed the voter registra-
tion requirements set forth in the NVRA. In making this argu-
ment, Arizona points to the provision in HAVA stating that:

    The requirements established by this title are mini-
    mum requirements and nothing in this title shall be
    construed to prevent a State from establishing elec-
17660                GONZALEZ v. ARIZONA
    tion technology and administration requirements that
    are more strict than the requirements so long as such
    State requirements are not inconsistent with the Fed-
    eral requirements under this subchapter or any law
    [including the NVRA and other federal voting regu-
    lations, § 15545].

§ 15484. But the “election technology and administration
requirements” referenced in this section refer to HAVA’s
requirements that states update election equipment (such as by
replacing punch card voting systems) and meet other voting
system standards. While § 15484 permits states to institute
their own technological and administrative improvements, it
does not allow them to impose additional requirements on the
voter registration process established by the NVRA. Indeed,
the section itself precludes states from adding requirements
“inconsistent with the Federal requirements under” the
NVRA. § 15484. Moreover, HAVA expressly provides that
“nothing [in HAVA] may be construed to authorize or require
conduct prohibited under [the NVRA].” § 15545(a)(4). This
language indicates Congress’s intent was to prevent HAVA
from interfering with NVRA’s comprehensive voter registra-
tion system. Accordingly, Arizona’s reliance on HAVA is
unavailing.

                              D

   [13] Finally, Arizona argues that we are foreclosed from
reviewing Gonzalez’s NVRA claim because the prior panel’s
ruling in Gonzalez I, which occurred at the preliminary
injunction phase of this case, already decided that the NVRA
does not supersede the changes to Arizona’s registration sys-
tem under Proposition 200. See Gonzalez I, 485 F.3d at
1050-51. Arizona asserts that this prior ruling is dispositive,
and there is no ground for the court to reconsider the issue
here.
                         GONZALEZ v. ARIZONA                       17661
   [14] Addressing this argument requires us to review the
applicability of our law of the case doctrine.16 Under this doc-
trine, “one panel of an appellate court will not as a general
rule reconsider questions which another panel has decided on
a prior appeal in the same case.” Hegler v. Borg, 50 F.3d
1472, 1475 (9th Cir. 1995) (citation and internal quotation
marks omitted). The doctrine applies to prior decisions based
on pure issues of law, even those made, as here, in the prelim-
inary stages of review of the same case. See Ranchers Cattle-
men Action Legal Fund United Stockgrowers of Am. v. U.S.
Dep’t of Agric., 499 F.3d 1108, 1114 (9th Cir. 2007).

   [15] “The effect of the doctrine is not dispositive, particu-
larly when a court is reconsidering its own judgment, for the
law of the case ‘directs a court’s discretion, it does not limit
the tribunal’s power.’ ” Mendenhall v. Nat. Transp. Safety
Bd., 213 F.3d 464, 469 (9th Cir. 2000) (quoting Arizona v.
California, 460 U.S. 605, 618 (1983)). In other words, “there
is nothing in the Constitution of the United States to require
[invocation of the doctrine], or to prevent a [court] from
allowing a past action to be modified while a case remains in
court.” King v. West Virginia, 216 U.S. 92, 101 (1910).
Instead, the doctrine’s utility is typically prudential: “it’s a
courteous and efficient way for a court to say ‘enough’s
enough’ when litigants seek reconsideration of prior interloc-
utory decisions.” Jeffries v. Wood (Jeffries V), 114 F.3d 1484,
1509 (9th Cir. 1997) (en banc) (Kozinski, J., dissenting) (cit-
ing cases), overruled on other grounds by Lindh v. Murphy,
521 U.S. 320 (1997).
  16
    Law of the case is part of a related set of preclusion principles that
includes stare decisis, res judicata, and collateral estoppel. 3 James Wm.
Moore et al., Moore’s Manual: Federal Practice & Procedure, § 30.01.
Though linked by the general animating purpose of judicial efficiency,
these principles are distinguished by the type or stage of litigation in
which they separately apply, and as a consequence each has its own policy
considerations. Id.
17662                    GONZALEZ v. ARIZONA
    That said, the policies animating the law of the case doc-
trine are undeniably fundamental. The doctrine “promotes the
finality and efficiency of the judicial process by protecting
against the agitation of settled issues.” Christianson v. Colt
Indus. Operating Corp., 486 U.S. 800, 816 (1988) (internal
quotation marks omitted). These are paramount concerns to
sound judicial administration, as “[a]n appellate court cannot
efficiently perform its duty to provide expeditious justice to
all if a question once considered and decided by it were to be
litigated anew in the same case upon any and every subse-
quent appeal.” Kimball v. Callahan, 590 F.2d 768, 771 (9th
Cir. 1979) (internal quotation marks omitted).

   Balanced against these valid concerns, however, are
equally strong considerations that occasionally pull in the
opposite direction. We have held that the “[l]aw of the case
should not be applied woodenly in a way inconsistent with
substantial justice.” United States v. Miller, 822 F.2d 828, 832
(9th Cir. 1987); see also Rent-A-Center, Inc. v. Canyon Tele-
vision & Appliance Rental, Inc., 944 F.2d 597, 602 (9th Cir.
1991) (“[T]he law of the case is an equitable doctrine that
should not be applied if it would be unfair.”); Loumar, Inc. v.
Smith, 698 F.2d 759, 762 (5th Cir. 1983) (“The law of the
case doctrine is not . . . a barrier to correction of judicial error.
It is a rule of convenience and utility and yields to adequate
reason . . . .”). Interests of efficiency and finality clash with
the responsibility of the court to not issue judgments known
to be wrong on the facts or law.

   [16] As a compromise between these sometimes counter-
vailing interests, we have identified three exceptional circum-
stances in which, on balance, we deem the concerns of finality
and efficiency outweighed. Law of the case should not oper-
ate as a constraint on judicial review where “(1) the decision
is clearly erroneous and its enforcement would work a mani-
fest injustice,17 (2) intervening controlling authority makes
  17
     As has been noted in prior cases, “[f]or some time, there have existed
in the Ninth Circuit two different formulations of the set of circumstances
                          GONZALEZ v. ARIZONA                         17663
reconsideration appropriate, or (3) substantially different evi-
dence was adduced at a subsequent trial.” Jeffries V, 114 F.3d
at 1489 (internal quotation marks and footnote omitted). Here,
Gonzalez argues that the first exception applies. We agree.

   The prior panel’s conclusion that the NVRA permits state-
imposed documentary proof of citizenship requirements on
registrants using the Federal Form was based on three provi-
sions of the statute. First, the panel indicated that under the
NVRA states must “either ‘accept and use the mail voter reg-
istration form prescribed by the Federal Election Commis-
sion’ or, in the alternative, ‘develop and use [their own]
form,’ as long as the latter conforms to the federal guide-
lines.” Gonzalez I, 485 F.3d at 1050 (second alteration in
original) (citations omitted). Second, the panel asserted that
the NVRA “prohibits states from requiring the form to be
notarized or otherwise formally authenticated.” Id. Last, the
panel described the NVRA as “permit[ting] states to
‘require[ ] such identifying information . . . as is necessary to
enable . . . election official[s] to assess the eligibility of the
applicant.” Id. (alterations in original). Construing these pro-
visions together, the panel concluded that the statute plainly
contemplates allowing states to require voters to present at
least some evidence of citizenship at the time of registration.
Id. at 1050-51.

in which a court may decline to follow the law of the case. The first for-
mulation . . . states that a court may depart from the law of the case if ‘the
previous decision is clearly erroneous and its enforcement would work a
manifest injustice.’ In contrast, the second formulation states that a court
may decline to follow the law of the case if ‘the first decision was clearly
erroneous’ or ‘a manifest injustice would otherwise result.” Tahoe-Sierra
Preservation Council, Inc. v. Tahoe Reg. Planning Agency, 216 F.3d 764,
787 n.43 (9th Cir. 2000) (citations and brackets omitted), aff’d on other
grounds, 535 U.S. 302 (2002); see also Mendenhall, 213 F.3d at 469 &
n.2. As in the other cases noting but not resolving this apparent conflict,
we need not settle this issue in the present case, because there are grounds
to satisfy the exception under either formulation of the standard.
17664                 GONZALEZ v. ARIZONA
   [17] As may be apparent from our NVRA analysis supra,
the prior panel’s conclusion was rooted in a fundamental mis-
reading of the statute. As the dissent acknowledges, see Dis-
sent at 17694-95, the NVRA does not give states freedom
“either” to accept and use the Federal Form “or, in the alterna-
tive,” develop their own form. See id. Rather, the NVRA
commands without exception that states “shall” accept and
use the Federal Form, and if they develop their own form, it
can be used only “in addition to” accepting and using the Fed-
eral Form, and still must meet all of the criteria of Section 7.
See § 1973gg-4(a). Thus, while Section 4 of the NVRA
applies the limitations of Section 7(b) to the states with
respect to the creation of their own state forms, nothing in the
text or structure of either provision supports reading Section
7(b) as giving the states any authority over or discretion to
modify the Federal Form. Insofar as the prior panel referred
to portions of the NVRA that relate to the Federal Form, see
Gonzalez I, 485 F.3d at 1050, those excerpts are directed
solely at the EAC, not the states. See § 1973gg-7(a)-(b).
These provisions cannot be said to “plainly allow states . . .
to require their citizens to present evidence of citizenship
when registering to vote” for federal elections via the Federal
Form. Id. at 1050-51.

   The dissent takes issue with our analysis of the prior
panel’s opinion, suggesting that the panel may have been
using “either . . . or, in the alternative” in a conjunctive sense.
Dissent 17693-95. We disagree. The prior panel’s statement
that states can “either accept and use” the Federal Form “or,
in the alternative” develop and use their own form cannot rea-
sonably be interpreted to mean that states can both accept and
use the Federal Form and also develop and use their own
form. Indeed, such an interpretation would be contrary to the
prior panel’s logic; the prior panel based its conclusion that
states could require registrants using the Federal Form to
show additional identification on the ground that states could
require use of their own forms in lieu of the Federal Form.
                     GONZALEZ v. ARIZONA                  17665
   As another basis for upholding the prior panel’s opinion,
the dissent suggests that the prior panel’s conclusion was cor-
rect although its reasoning was erroneous, because “accept
and use” in § 1973gg-4(a)(1) can be read to mean “accept . . .
for a particular purpose [but] not have it be sufficient to sat-
isfy that purpose.” Dissent 17697. In other words, the dissent
argues that although states are required to “accept and use”
the Federal Form, the NVRA leaves them free to require pro-
spective voters to comply with additional registration require-
ments beyond those mandated by the Federal Form. As noted
above, Arizona makes a similar argument. This argument is
inconsistent with the language and structure of the NVRA.
The dissent’s strained interpretation would make the EAC’s
procedure for consultation and development of the Federal
Form under Section 7(a) an empty exercise, because any state
could require registrants to comply with additional state
requirements even if they register with the Federal Form. As
discussed above, under an Elections Clause framework, we do
not strain the language of the NVRA to render it harmonious
with Proposition 200. In the context of the NVRA, “accept
and use” can mean only one thing: the states must “accept and
use” the Federal Form as a fully sufficient means of register-
ing to vote in federal elections.

   [18] Reasoning from a fundamental misreading of the stat-
ute, the prior panel reached a conclusion that was clear error.
See Jeffries V, 114 F.3d at 1489. The text, structure, and pur-
pose of the NVRA simply cannot bear the prior panel’s inter-
pretation. Moreover, this case represents an “exceptional
circumstance,” where the effect of the erroneous decision,
were it to stand, would result in a manifest injustice. Id. at
1489, 1492. Not only does the erroneous conclusion impede
the implementation of a major congressional enactment, but
it poses a significant inequity to citizens who are required
under the state law to navigate obstacles that do not exist
under federal law in pursuit of their fundamental right to vote.
See id. at 1492 (stating that manifest injustice may be found
where the challenged decision involves a “significant inequi-
17666                      GONZALEZ v. ARIZONA
ty”). Though we are sensitive to the cautious approach courts
should take in deciding to alter an earlier panel’s decision,
because the prior decision in this case not only reached a
clearly erroneous result, but reached that result on the basis of
a misconstruction of the statute, we are convinced that there
are appropriately exceptional circumstances to review the
decision here.

   The fact that the prior panel’s decision was contained in a
published opinion does not strip us of our discretion to review
its conclusions, because no subsequent published decision has
relied upon the prior panel’s decision for the proposition to be
overturned. See, e.g., Mendenhall, 213 F.3d at 469 (reversing
a prior published appellate opinion as clearly erroneous under
the exceptions to the law of the case); Tahoe-Sierra, 216 F.3d
at 786-87 (same). Under such circumstances, the law of the
circuit doctrine does not preclude us from revising prior deci-
sions in the same case under the established exceptions to the
law of the case. See Jeffries V, 114 F.3d 1484.

   This conclusion was made clear in Jeffries V, an en banc
decision highlighting the workings of our law of the case doc-
trine. Although the procedural history of the Jeffries decisions
is complex,18 the central question addressed in Jeffries V was
   18
      The Jeffries decisions were a series of five opinions in response to a
habeas petition by Patrick Jeffries. Jeffries had been sentenced to death by
a jury, but petitioned for relief on the ground of juror misconduct (he
claimed that one juror had informed other jurors that Jeffries was a con-
victed armed robber). The district court rejected this claim on the ground
that even if true, this fact would not have affected the verdict. On appeal,
a panel of this court initially upheld the district court’s conclusion, Jeffries
v. Blodgett (Jeffries I), 974 F.2d 1179 (9th Cir. 1992), but then granted
Jeffries’s petition for rehearing and itself on the ground that Jeffries I con-
flicted with precedent. Jeffries v. Blodgett (Jeffries II), 988 F.2d 923 (9th
Cir. 1993). The panel then rejected the state’s petition for rehearing, but
amended Jeffries II to make clear that the claim of juror misconduct, if
true, would have had a “substantial and injurious effect” on the verdict.
Jeffries v. Blodgett (Jeffries III), 5 F.3d 1180 (9th Cir. 1993). On remand,
                          GONZALEZ v. ARIZONA                         17667
whether Jeffries IV, 75 F.3d 491, erred in its application of an
exception to the law of the case. The Jeffries IV panel held
that it could reverse its prior holding in Jeffries III, 5 F.3d
1180, under the first exception to the law of the case , because
Jeffries III was “clearly erroneous and would work a manifest
injustice.” Jeffries IV, 75 F.3d at 494. In Jeffries V, we
rejected the state’s argument that we should avoid reaching
the law of the case issue and instead decide the case on the
merits, due to the importance of the law of the case doctrine
to our jurisprudence. See 114 F.3d at 1492. After a careful
review of the law of the case doctrine, we concluded in Jef-
fries V that the Jeffries IV panel had erred in overturning Jef-
fries III, because none of the exceptions to the law of the case
were applicable. Id. at 1489. Focusing on the first exception,
see id. at 1489 n.2, we concluded that Jeffries III was not
clearly erroneous, and would not work a manifest injustice,
and accordingly Jeffries IV had erred in reversing it. Id. at
1489.

   The decision in Jeffries V was also supported on stare deci-
sis grounds. Noting that two Ninth Circuit panels had already
relied on Jeffries III at the time Jeffries IV was decided, see
Thompson v. Borg, 74 F.3d 1571, 1575 n.1 (9th Cir. 1996);
Lawson v. Borg, 60 F.3d 608, 612 (9th Cir. 1995), we stated
that a panel “must be exceedingly careful in altering the law
of its earlier opinion” in circumstances “when subsequent

the district court held that juror misconduct had in fact occurred and
granted Jeffries’s petition. See Jeffries V, 114 F.3d at 1488. After the state
appealed this ruling, the panel again reversed itself, holding that it had
interpreted precedent too broadly in Jeffries III, and that the law of the
case did not prevent reversal of Jeffries III because that decision was
“clearly erroneous and would work a manifest injustice.” See Jeffries v.
Wood (Jeffries IV), 75 F.3d 491 (9th Cir. 1996). Accordingly, the panel
reinstated its denial of Jeffries’s habeas petition. Jeffries petitioned for
rehearing en banc, which we granted to determine, among other things,
whether Jeffries IV had erred in reversing Jeffries III. See Jeffries V, 114
F.3d at 1488.
17668                GONZALEZ v. ARIZONA
panels have relied on the initial decision” because
“[o]therwise, intra-circuit conflict may arise, posing serious
difficulties.” Jeffries V, 114 F.3d at 1492. Moreover, we noted
that “to reach its decision properly, the Jeffries IV panel
would have had to reverse Lawson,” which could not properly
be done by a three-judge panel. Id. In explaining the effect of
prior published opinions on the applicability of our exceptions
to the law of the case, the en banc court in Jeffries V notably
did not adopt the view of the dissent in that case that “no
three-judge panel may reconsider a rule of law embodied in
a prior published opinion,” even one in the same case, Jeffries
V, 114 F.3d at 1511 (Kozinski, J., dissenting). In sum, under
our en banc decision in effries V, though a panel cannot over-
turn prior published opinions in different cases, it may over-
turn a prior published opinion in the same case if the
exceptions to the law of the case are applicable.

   [19] In this case, no other panel of this court has relied
upon the prior panel’s decision for the proposition that the
NVRA does not supersede additional state requirements for
federal voter registration. Where no subsequent opinion has
relied on the prior published opinion for the proposition to be
overturned, there is no stare decisis problem and conse-
quently the law of the circuit doctrine does not prohibit revis-
ing the prior opinion.

   Despite our decision in Jeffries V, the dissent argues that
we are bound by a rule that we can never reverse a prior pub-
lished opinion, even one in the same case. Dissent 17684-85.
On its face, this is the same rule that was proposed in the Jef-
fries V dissent and rejected by the majority. To overcome this
obstacle, the dissent claims that a footnote in United States v.
Washington (Washington IV), 593 F.3d 790 (9th Cir. 2010)
(en banc), overruled Jeffries V on this issue. Dissent 17685.

  We disagree. Washington IV was heard en banc to resolve
an inconsistency between two conflicting lines of precedent
on the question whether federal recognition of a tribe has a
                     GONZALEZ v. ARIZONA                   17669
bearing on that tribe’s entitlement to fishing rights under a
specific treaty. See 593 F.3d at 792-93, 798. In United States
v. Washington (Washington III), 394 F.3d 1152 (9th Cir.
2005), we held that the intervening federal recognition of a
tribe “was a sufficient condition for the establishment of treaty
fishing rights.” Id. at 1158. But in Greene v. United States
(Greene I), 996 F.2d 973, 976-77 (9th Cir. 1993), and Greene
v. Babbitt (Greene II), 64 F.3d 1266, 1270-71 (9th Cir. 1995),
we held that federal recognition of a tribe could have no effect
on treaty fishing rights. On appeal from the district court’s
decision following Washington III, we explained that “the
conflict in our precedent led us to rehear the matter en banc
without awaiting a three-judge decision.” Washington IV, 593
F.3d at 798 n.9. This is correct: a three-judge panel could not
have resolved the split between Washington III and Greene I
and II. The footnote on which the dissent relies further
explained that en banc review was necessary because, “[e]ven
if the panel could have revisited Washington III under one of
the exceptions to the law of the case, it still would have been
bound by that published opinion as the law of the circuit . . .
‘[W]e have no discretion to depart from precedential aspects
of our prior decision . . . under the general law-of-the-circuit
rule.’ ” Washington IV, 593 F.3d at 798 n.9 (citations omitted)
(quoting Old Person v. Brown, 312 F.3d 1036, 1039 (9th Cir.
2002)).

   In light of the detailed discussion in Jeffries V regarding
exceptions to the law of the case doctrine, we cannot read this
sentence as overruling this longstanding doctrine. While Jef-
fries V was expressly decided on the law-of-the-case ground,
nothing in Washington IV turned on the law of the case doc-
trine. Nor did Washington IV expressly consider or overrule
our en banc decision in Jeffries V. “In our circuit, statements
made in passing, without analysis, are not binding precedent.”
Thacker v. FCC (In re Magnacom Wireless, LLC), 503 F.3d
984, 993-94 (9th Cir. 2007); see also United States v. John-
son, 256 F.3d 895, 915 (9th Cir. 2001) (en banc) (Kozinski,
J,. concurring) (“Of course, not every statement of law in
17670                     GONZALEZ v. ARIZONA
every opinion is binding on later panels. Where it is clear that
a statement is made casually and without analysis, where the
statement is uttered in passing without due consideration of
the alternatives, or where it is merely a prelude to another
legal issue that commands the panel’s full attention, it may be
appropriate to re-visit the issue in a later case.”). The Wash-
ington IV footnote on which the dissent relies neither exhibits
“reasoned consideration” of our law of the case doctrine,
Johnson, 256 F.3d at 914, nor discusses an issue “germane,”
id., to the resolution of Washington IV. In fact, it can more
accurately be described as informational, “casual[,] and with-
out analysis,” id. at 915. Moreover, the Washington IV foot-
note is silent on the question whether subsequent published
opinions had relied on Washington III, which Jeffries V held
could preclude an application of the exceptions to the law of
the case. Jeffries V, 114 F.3d at 1489. Accordingly, we
decline to hold that this footnote overruled sub silentio the
reasoned analysis of the en banc court in Jeffries V.19

   [20] Because, as set forth above, the prior panel’s decision
on the NVRA issue meets the standard of a recognized law of
the case exception, we have discretion to review that decision,
and we have chosen to exercise that discretion here.

                                     E

   Perhaps the instructions to the Federal Form put it best in
stating: “you can use the application in this booklet to: Regis-
ter to vote in your State.” Under the NVRA, prospective vot-
ers seeking to register in federal elections need only complete
and submit the Federal Form. If this sounds simple, it is by
  19
    The other cases cited by the dissent in support of its version of the law
of the circuit doctrine were decided by three-judge panels and thus could
not have overruled Jeffries V. See Minidoka Irrigation Dist. v. Dep’t of
Interior, 406 F.3d 567 (9th Cir. 2005); Old Person, 312 F.3d 1036; Hilao
v. Estate of Marcos, 103 F.3d 767 (9th Cir. 1996). One of these cases also
pre-dated Jeffries. See Hilao, 103 F.3d 767.
                         GONZALEZ v. ARIZONA                        17671
design. Congress enacted the NVRA to increase federal regis-
tration by streamlining the registration process and eliminat-
ing complicated state-imposed hurdles to registration, which
it determined were driving down voter turnout rates. Proposi-
tion 200 imposes such a hurdle. In light of Congress’s para-
mount authority to “make or alter” state procedures for
federal elections, see Foster, 522 U.S. at 69; Siebold, 100
U.S. at 371, we hold that the NVRA’s comprehensive regula-
tion of federal election registration supersedes Arizona’s doc-
umentary proof of citizenship requirement, Ariz. Rev. Stat.
§§ 16-152(A)(23), 16-166(F).

   Because we hold Arizona’s registration requirement void
under the NVRA, we need not reach Gonzalez’s claim that
the documentary proof of citizenship requirement imposes
greater burdens of registration on naturalized citizens than on
non-naturalized citizens and burdens the fundamental right to
vote in violation of the Fourteenth Amendment’s Equal Pro-
tection Clause.

                                    III

   [21] The remainder of our analysis focuses solely on the
validity of Arizona’s polling place provision, Ariz. Rev. Stat.
§ 16-579.20 That statute requires voters to show proof of iden-
tification before voting at the polls. Id. We first consider Gon-
zalez’s appeal from the district court’s decision that
   20
      Because Congress’s authority under the Elections Clause is limited to
preempting regulations related to federal elections, our holding invalidat-
ing Proposition 200’s registration requirement does not prevent Arizona
from applying its requirement in state election registrations. However,
Arizona has presented its system of voter registration under Proposition
200 as concurrently registering voters for state and federal elections, and
has not indicated that, in the event Gonzalez prevails on the NVRA claim,
it plans to establish a separate state registration system. We therefore do
not consider whether Proposition 200’s registration requirement, as
applied only to state registrations, is valid under Gonzalez and ITCA’s
remaining claims.
17672                   GONZALEZ v. ARIZONA
Proposition 200 does not violate § 2 of the VRA, 42 U.S.C.
§ 1973.

                                   A

   [22] Section 2(a) of the VRA prohibits states from impos-
ing voting qualifications that result in the “denial or abridge-
ment of the right of any citizen of the United States to vote
on account of race or color.” 42 U.S.C. § 1973(a). A violation
of § 2 is established “if, based on the totality of circum-
stances, it is shown that the political processes leading to
nomination or election in the State or political subdivision are
not equally open to participation” by members of a protected
class “in that its members have less opportunity than other
members of the electorate [1] to participate in the political
process and [2] to elect representatives of their choice.”
§ 1973(b). Said otherwise, a plaintiff can prevail in a § 2
claim only if, “based on the totality of the circumstances, the
challenged voting practice results in discrimination on
account of race.”21 Farrakhan v. Washington, 338 F.3d 1009,
1015 (9th Cir. 2003); see also United States v. Blaine Cnty.,
Mont., 363 F.3d 897, 903 (9th Cir. 2004). A violation of Sec-
tion 2 does not require a showing of discriminatory intent,
only discriminatory results. See Chisom v. Roemer, 501 U.S.
380, 383 (1991); Ruiz v. City of Santa Maria, 160 F.3d 543,
557 (9th Cir. 1998).

   In applying the totality of the circumstances test, “a court
must assess the impact of the contested structure or practice
on minority electoral opportunities on the basis of objective
factors.” Thornburg v. Gingles, 478 U.S. 30, 44 (1986) (inter-
nal quotation marks omitted). In conducting a § 2 analysis,
courts are required to make a “searching inquiry” into “how
the challenged [state] practice interacts with social and histor-
  21
    This approach applies both to claims of vote denial and of vote dilu-
tion. Smith v. Salt River Project Agric. Improvement & Power Dist., 109
F.3d 586, 596 n.8 (9th Cir. 1997).
                      GONZALEZ v. ARIZONA                   17673
ical conditions to cause an inequality in the opportunities
enjoyed by” minorities in the electoral process. Farrakhan,
338 F.3d at 1016, 1020 (internal quotation marks omitted). In
Gingles, the Supreme Court cited a non-exhaustive list of nine
factors (generally referred to as the “Senate Factors” because
they were discussed in the Senate Report on the 1982 amend-
ments to the VRA) that courts should consider in making this
totality of the circumstances assessment. 478 U.S. at 44-45.
Relevant here, the factors direct courts to consider the history
of official state discrimination against the minority with
respect to voting, the extent to which voting in the state is
racially polarized, and “the extent to which members of the
minority group in the state or political subdivision bear the
effects of discrimination in such areas as education, employ-
ment and health, which hinder their ability to participate
effectively in the political process.” Id. at 36-37 (quoting S.
Rep. No. 97-417, at 28-29 (1982), as reprinted in 1982
U.S.C.C.A.N. 177, 206-07). “[T]here is no requirement that
any particular number of factors be proved, or that a majority
of them point one way or the other.” Farrakhan v. Gregoire,
590 F.3d 989, 999 (9th Cir. 2010) (internal quotation marks
omitted).

   Gonzalez alleges that Proposition 200’s registration and
polling place identification requirements violate § 2 by dispa-
rately affecting Latino voters, unlawfully diluting their right
to vote and providing them with less opportunity than other
members of the electorate to participate in the political pro-
cess. Considering statistical evidence on the existence of dis-
parate impact on Latino registrants and voters, the district
court determined that the limited statistical disparity between
the Latinos’ registration and voting as compared to the rest of
the electorate was not statistically significant. Turning to the
Senate Factors listed above, the district court found that
Latinos had suffered a history of discrimination in Arizona
that hindered their ability to participate in the political process
fully, that there were socioeconomic disparities between
17674                 GONZALEZ v. ARIZONA
Latinos and whites in Arizona, and that Arizona continues to
have some degree of racially polarized voting.

   Despite the presence of limited statistical disparity and
some of the Senate Factors, however, the district court con-
cluded that Gonzalez’s claim failed because there was no
proof of a causal relationship between Proposition 200 and
any alleged discriminatory impact on Latinos. The district
court noted that not a single expert testified to a connection
between the requirement that Latinos show identification
under Proposition 200 and the observed difference in voter
registration and voting rates of Latinos. Furthermore, the dis-
trict court held that Gonzalez failed to explain how Proposi-
tion 200’s requirements interact with the social and historical
climate of discrimination to impact Latino voting in Arizona.
Without a causal link between the voting practice and prohib-
ited discriminatory result, the district court concluded that
Gonzalez had not proven that Proposition 200 results in dis-
crimination “on account of race or color,” and that the claim
must therefore be denied.

                                B

   Because a § 2 analysis requires the district court to engage
in a “searching practical evaluation of the past and present
reality,” Gingles, 478 U.S. at 45 (internal quotation marks
omitted), a district court’s examination is “intensely fact-
based and localized,” Salt River, 109 F.3d at 591. We there-
fore “[d]efer[ ] to the district court’s superior fact-finding
capabilities,” id., and review for clear error the district court’s
findings of fact, including its ultimate finding whether, under
the totality of the circumstances, the challenged practice vio-
lates § 2, Old Person v. Cooney, 230 F.3d 1113, 1119 (9th
Cir. 2000) (citing Gingles, 478 U.S. at 78-79). We review de
novo the district court’s legal determinations and mixed find-
ings of law and fact. Salt River, 109 F.3d at 591. Again,
because we have held that Proposition 200’s voter registration
requirements are superseded by the NVRA, supra Part II, we
                     GONZALEZ v. ARIZONA                   17675
consider only Proposition 200’s requirement that voters show
identification at the polls, Ariz. Rev. Stat. § 16-579.

   [23] The district court did not clearly err in concluding that
Gonzalez failed to establish that Proposition 200’s require-
ments caused any disparate impact on Latinos. To prevail
under § 2, a plaintiff must prove “a causal connection
between the challenged voting practice and a prohibited dis-
criminatory result.” Salt River, 109 F.3d at 595 (alteration
omitted). “[A] bare statistical showing of disproportionate
impact on a racial minority does not satisfy the § 2 ‘results’
inquiry.” Id. at 595 (emphasis in original) (collecting cases).
To prove that such a causal relationship exists, a plaintiff need
not show that the challenged voting practice caused the dispa-
rate impact by itself. See Farrakhan, 338 F.3d at 1018-19.
Rather, pursuant to a totality of the circumstances analysis,
the plaintiff may prove causation by pointing to the interac-
tion between the challenged practice and external factors such
as surrounding racial discrimination, and by showing how that
interaction results in the discriminatory impact. Id. at 1019.
But even under this broad totality of the circumstances analy-
sis, the causation requirement is crucial: a court may not
enjoin a voting practice under § 2 unless there is evidence that
the practice results in a denial or abridgement of the rights of
a citizen on account of race or color. § 1973(a). If there is no
evidence that the voting practice resulted in any such dispa-
rate impact, there is no violation and thus no basis for injunc-
tive relief.

   [24] The district court correctly applied this standard here.
The challenged practice at issue is Proposition 200’s require-
ment that voters show identification at the polls. To prove
causation, Gonzalez had to establish that Proposition 200’s
requirement that voters must produce forms of identification,
as applied to Latinos, resulted in a prohibited discriminatory
result. Here, Gonzalez alleged in his complaint that “Latinos,
among other ethnic groups, are less likely to possess the
forms of identification required under Proposition 200 to . . .
17676                    GONZALEZ v. ARIZONA
cast a ballot,” but produced no evidence supporting this alle-
gation. The record does include evidence of Arizona’s general
history of discrimination against Latinos and the existence of
racially polarized voting. But Gonzalez adduced no evidence
that Latinos’ ability or inability to obtain or possess identifi-
cation for voting purposes (whether or not interacting with the
history of discrimination and racially polarized voting)
resulted in Latinos having less opportunity to participate in
the political process and to elect representatives of their
choice. Without such evidence, we cannot say that the district
court’s finding that Gonzalez failed to prove causation was
clearly erroneous. Therefore we affirm the district court’s
denial of this claim.22

                                   IV

   Gonzalez I, which considered Gonzalez and ITCA’s appeal
from the district court’s denial of a preliminary injunction,
concluded that Arizona’s registration identification require-
ment was not a poll tax. See 485 F.3d at 1049. We held that
the registration requirement did not (1) force voters “to
choose between paying a poll tax and providing proof of citi-
zenship when they register to vote,” the standard set forth in
Harman v. Forssenius, 380 U.S. 528, 541-42 (1965); and did
not (2) “make[ ] the affluence of the voter or payment of any
fee an electoral standard,” as was held impermissible under
the Fourteenth Amendment in Harper v. Virginia State Board
of Elections, 383 U.S. 663, 666 (1966). Gonzalez I, 485 F.3d
at 1049 (internal quotation marks omitted) (brackets in origi-
nal).

  [25] Here, Gonzalez and ITCA argue that Proposition 200
imposes an unconstitutional poll tax in violation of the
  22
    Gonzalez also argues that the district court erred in evaluating one of
the Senate Factors and in concluding that the disparate impact on Latinos
was statistically insignificant. Because Gonzalez’s failure to show causa-
tion is dispositive, however, we need not reach these issues.
                     GONZALEZ v. ARIZONA                  17677
Twenty-fourth Amendment. Separately, ITCA asserts that
Proposition 200 is also a poll tax under the Fourteenth
Amendment. Guided by the analysis in Gonzalez I, we con-
clude that Proposition 200’s polling place identification
requirement is not a poll tax under either constitutional provi-
sion.

                               A

  The Twenty-fourth Amendment provides that:

    The right of citizens of the United States to vote in
    any primary or other election for President or Vice
    President, for electors for President or Vice Presi-
    dent, or for Senator or Representative in Congress,
    shall not be denied or abridged by the United States
    for or any State by reason of failure to pay any poll
    tax or other tax.

U.S. Const. amend. XXIV.

   Gonzalez does not argue that requiring voters to show iden-
tification at the polls is itself a poll tax. Rather, Gonzalez
argues that, because some voters do not possess the identifica-
tion required under Proposition 200, those voters will be
required to spend money to obtain the requisite documenta-
tion, and that this payment is indirectly equivalent to a tax on
the right to vote.

   [26] This analysis is incorrect. Although obtaining identifi-
cation required under Arizona’s statute may have a cost, it is
neither a poll tax itself (it is not a fee imposed on voters as
a prerequisite for voting), nor is it a burden imposed on voters
who refuse to pay a poll tax. Cf. Harman, 380 U.S. at 541-42.

  Our conclusion is consistent with Harman, the only
Supreme Court case considering the Twenty-fourth Amend-
ment’s ban on poll taxes. In that case, the Court considered
17678                     GONZALEZ v. ARIZONA
a state statute that required voters to either pay a $1.50 poll
tax on an annual basis or go through “a plainly cumbersome
procedure,” id. at 541, for filing an annual certificate of resi-
dence. Id. at 530-32. There was no dispute that the $1.50 fee
was a poll tax barred by the Twenty-Fourth Amendment. See
id. at 540. Accordingly, the only question before the Court
was whether the state “may constitutionally confront the fed-
eral voter with a requirement that he either pay the customary
poll taxes as required for state elections or file a certificate of
residence.” Id. at 538. The Court enunciated the rule that a
state may not impose “a material requirement solely upon
those who refuse to surrender their constitutional right to vote
in federal elections without paying a poll tax.” Id. at 542.
Applying this rule, the Court determined that the state’s certif-
icate of residence requirement was a material burden: among
other things, the procedure for filing the certificate was
unclear, the requirement that the certificate be filed six
months before the election “perpetuat[ed] one of the disen-
franchising characteristics of the poll tax which the Twenty-
fourth Amendment was designed to eliminate,” and the state
had other alternatives to establish that voters were residents,
including “registration, use of criminal sanction[s], purging of
registration lists, [and] challenges and oaths.” Id. at 541-43.
Accordingly, the Court concluded that “[w]e are thus con-
strained to hold that the requirement imposed upon the voter
who refuses to pay the poll tax constitutes an abridgment of
his right to vote by reason of failure to pay the poll tax.” Id.
at 542.

   [27] Arizona’s polling place requirement is not analogous.
Proposition 200’s requirement that voters identify themselves
at the polling place is not a poll tax, as stated in Gonzalez I.
485 F.3d at 1049. Voters have only to verify their eligibility
by showing identification at the polls,23 which does not consti-
  23
     Voters who use an early ballot to vote do not even have to show iden-
tification. Ariz. Rev. Stat. § 16-550(A) (for early ballots, elector identity
is verified by signature comparison alone).
                         GONZALEZ v. ARIZONA                       17679
tute a tax, a point which Gonzalez does not dispute. Nor does
Proposition 200’s identification requirement place a material
burden on voters “solely because of his refusal to waive the
constitutional immunity” to a poll tax. Harman, 380 U.S. at
542. Voters are not given the choice between paying a poll tax
or obtaining identification; all voters are required to present
identification at the polling place. See Gonzalez I, 485 F.3d at
1049. Cf. Harman, 380 U.S. at 541-42. Because “Arizona’s
system does not, as a matter of law, qualify as a poll tax,” the
district court was correct in concluding that Proposition 200’s
requirement of identification at the polling place did not vio-
late the Twenty-fourth Amendment. See Gonzalez I, 485 F.3d
at 1049.

                                    B

   [28] Nor is Proposition 200’s requirement that voters show
identification at the polling place a poll tax under the Four-
teenth Amendment’s Equal Protection Clause.24 Harper is the
leading Supreme Court case considering whether a state law
is a poll tax under the Equal Protection Clause. In Harper, the
Supreme Court held that a state law levying an annual $1.50
poll tax on individuals exercising their right to vote in the
state was unconstitutional under the Equal Protection Clause.
Id. at 665-66 & n.1. The Court held that “the interest of the
State, when it comes to voting, is limited to the power to fix
qualifications,” id. at 668, and that the imposition of poll
taxes fell outside this power because “[w]ealth, like race,
creed, or color, is not germane to one’s ability to participate
  24
     ITCA’s briefing collapses the Twenty-fourth Amendment and Four-
teenth Amendment poll tax claims into a single argument. But these are
different claims that arise under different constitutional amendments. The
Twenty-fourth Amendment extends only to federal elections, see Harman,
380 U.S. at 540 (holding that “the Twenty-fourth Amendment abolish[ed]
the poll tax as a requirement for voting in federal elections”), while the
Fourteenth Amendment also invalidates restrictions on the right to vote in
state elections, see Harper, 383 U.S. at 666. Therefore, we have addressed
these claims separately.
17680                     GONZALEZ v. ARIZONA
intelligently in the electoral process,” id. Because the state’s
poll tax made affluence of the voter an electoral standard, and
such a standard is irrelevant to permissible voter qualifica-
tions, the Court concluded that the tax was invidiously dis-
criminatory and a per se violation of the Equal Protection
Clause. Id. at 666-67.

   [29] Arizona’s polling place identification requirement
falls outside of Harper’s rule that “restrictions on the right to
vote are invidious if they are unrelated to voter qualifica-
tions.” Crawford v. Marion Cnty. Elections Bd., 128 S. Ct.
1610, 1616 (2008) (plurality opinion). The requirement that
individuals show documents proving their identity is not an
invidious classification based on impermissible standards of
wealth or affluence, even if some individuals have to pay for
them. On the contrary, requiring individuals to show identifi-
cation falls squarely within the state’s power to fix core voter
qualifications. Photo identification addresses the most basic
voter criterion: that individuals seeking to cast a ballot are
who they purport to be and are in fact eligible to vote. Even
ITCA admits that this is a valid state interest.

   ITCA argues that the Court’s more recent decision in
Crawford, 128 S.Ct. 1610,25 extended Harper’s holding to
include a prohibition on indirect fees, such as fees or costs
necessary to obtain required identification documents. ITCA
seeks the benefit of Harper’s per se rule that such an electoral
standard is invidiously discriminatory, and thus violates the
Equal Protection Clause.
  25
    Crawford was decided by the Supreme Court after this court’s holding
in Gonzalez I. ITCA frames Crawford as an “intervening controlling
authority” that provides a basis for this court to reconsider its decision in
Gonzalez I that Arizona’s registration requirement is not a poll tax.
Because Gonzalez I did not address whether the polling place identifica-
tion requirement constituted a poll tax, see 485 F.3d at 1048-49, we need
not address this argument.
                         GONZALEZ v. ARIZONA                        17681
   This argument is not consistent with Crawford. Crawford
involved an Indiana state requirement that a citizen voting in
person or at the office of the circuit court clerk before election
day present a photo identification card issued by the govern-
ment. Id. at 1613. The state would provide a free photo identi-
fication to “qualified voters able to establish their residence
and identity.” Id. at 1614. A number of plaintiffs challenged
this requirement on the ground that the “new law substantially
burdens the right to vote in violation of the Fourteenth
Amendment.” Id.

   Although the Court was unable to agree on the rationale for
upholding Indiana’s photo identification requirement,26 nei-
ther the lead opinion nor the concurrence held that Harper’s
per se rule applied to Indiana’s photo identification require-
ment. See id. at 1624. The lead opinion, upon which ITCA
relies, explained that Harper’s “litmus test” made “even ratio-
nal restrictions on the right to vote . . . invidious if they are
unrelated to voter qualifications.” Id. at 1616. But according
to the lead opinion, later election cases had moved away from
Harper to apply a balancing test to state-imposed burdens on
the voting process. Id. Under these later cases, a court “must
identify and evaluate the interests put forward by the State as
justifications for the burden imposed by its rule, and then
make the ‘hard judgment’ that our adversary system
demands.” Id. The lead opinion then proceeded to apply this
balancing test to the Indiana photo identification requirement.
Id. Crawford did not purport to overrule Harper, however,
which remains as an example of an electoral standard for
which a state would never have sufficiently weighty interests
to justify the requirement that a fee be paid in order to vote.
Id. Because Crawford did not extend Harper’s per se rule to
other burdens imposed on voters, but left it applicable only to
poll tax requirements, Crawford does not support ITCA’s
  26
     The lead opinion authored by Justice Stevens was joined by Chief Jus-
tice Roberts and Justice Kennedy. Justice Scalia filed a concurring opinion
joined by Justice Thomas and Alito. The other three justices dissented.
17682                 GONZALEZ v. ARIZONA
argument that Proposition 200’s identification requirement is
per se invalid under Harper.

   Although ITCA’s reliance on Crawford is not entirely
clear, ITCA does not appear to argue that Proposition 200’s
identification requirement is invalid under Crawford’s balanc-
ing test. ITCA does not, for example, claim that the burden
imposed by the photo identification was impermissibly heavy
in light of Arizona’s legitimate interests. Such an argument
would be unavailing in any event. The lead opinion in Craw-
ford held that the burden imposed on citizens who must obtain
a photo identification document was not sufficiently heavy to
support a facial attack on the constitutionality of the state law,
in light of the state’s legitimate interests in deterring and
detecting voter fraud, modernizing election procedures, and
safeguarding voter confidence. Id. at 1617, 1623. The same
reasoning is applicable here. While the lead opinion noted that
photo identification cards were provided free by Indiana, the
lead opinion also recognized that to obtain Indiana’s free
photo identification cards, individuals were required to “pres-
ent at least one ‘primary’ document, which can be a birth cer-
tificate, certificate of naturalization, U.S. veterans photo
identification, U.S. military photo identification, or a U.S.
passport.” Id. at 1621 n.17. Obtaining these primary docu-
ments, the Supreme Court acknowledged, may require pay-
ment of a fee. Id. Because Proposition 200 identification
requirements include these same sorts of primary documents,
Proposition 200’s requirements are no more burdensome than
those upheld by Crawford. ITCA does not argue that Arizo-
na’s interests in imposing a photo identification requirement
are any less weighty than Indiana’s interests in deterring and
detecting voter fraud, modernizing election procedures, and
safeguarding voter confidence. Therefore, even under the bal-
ancing test set forth in the Crawford lead opinion, we would
uphold Proposition 200’s polling place identification require-
ment against a facial challenge.

  [30] In sum, because any payment associated with obtain-
ing the documents required under Proposition 200’s photo
                        GONZALEZ v. ARIZONA                  17683
identification provision is related to the state’s legitimate
interest in assessing the eligibility and qualifications of voters,
the photo identification requirement is not an invidious
restriction under Harper, and the burden is minimal under
Crawford. As such, Arizona’s polling place photo identifica-
tion requirement does not violate the Fourteenth Amend-
ment’s Equal Protection Clause.

                                   V

   [31] Our system of dual sovereignty, which gives the state
and federal governments the authority to operate within their
separate spheres, “is one of the Constitution’s structural pro-
tections of liberty.” Printz v. United States, 521 U.S. 898, 921
(1997). “Just as the separation and independence of the coor-
dinate branches of the Federal Government serve to prevent
the accumulation of excessive power in any one branch, a
healthy balance of power between the States and the Federal
Government will reduce the risk of tyranny and abuse from
either front.” Id. (quoting Gregory, 501 U.S. at 458). Despite
our respect for the state’s exercise of its sovereign authority,
however, the Constitution’s text requires us to enforce the
specific enumerated powers that are bestowed on the federal
government and denied to the states. The authority granted to
Congress under the Elections Clause to “make or alter” state
law regulating procedures for federal elections is one such
power. The Framers of the Constitution were clear that the
states’ authority to regulate extends only so far as Congress
declines to intervene. U.S. Const. art. 1, § 4, cl. 1; e.g., Foster,
522 U.S. at 69. Given the paramount authority delegated to
Congress by the Elections Clause, we conclude that the
NVRA, which implemented a comprehensive national system
for registering federal voters, supersedes Arizona’s conflict-
ing voter registration requirement for federal elections. We
uphold Arizona’s polling place identification requirement
with respect to all other claims.27
  27
    Each party will bear its own costs on appeal.
17684                     GONZALEZ v. ARIZONA
   AFFIRMED in part and REVERSED in part.



Chief Judge KOZINSKI, dissenting in large part:*

   As the majority belatedly acknowledges more than halfway
into its opinion, we don’t come to this case with a blank slate.
A prior panel has already held in a published opinion that
Proposition 200 isn’t preempted because the National Voter
Registration Act (“NVRA”) “plainly allow[s] states, at least
to some extent, to require their citizens to present evidence of
citizenship when registering to vote.” Gonzalez v. Arizona,
485 F.3d 1041, 1050-51 (9th Cir. 2007) (“Gonzalez I”). That
is law of the circuit and therefore binding on us. See, e.g.,
Miller v. Gammie, 335 F.3d 889, 899-900 (9th Cir. 2003) (en
banc). Even if it weren’t, it’s law of the case and can’t be
lightly disregarded for that reason. See, e.g., Merritt v.
Mackey, 932 F.2d 1317, 1322 (9th Cir. 1991). The majority
refuses to accept the consequences of this reality. First, it
evades law of the circuit by creating an exception that is
squarely foreclosed by a recent unanimous en banc opinion.
The majority then weakens our rules governing law of the
case by declaring that Gonzalez I’s interpretation of the
NVRA is “clearly erroneous” when it’s clearly not. Because
I believe that we must take precedent seriously and that Gon-
zalez I was correctly decided, I dissent from the majority’s
conclusion that the NVRA preempts Arizona’s voter registra-
tion requirement.

   *I concur in the portion of the judgment upholding Proposition 200’s
polling place provision, Ariz. Rev. Stat. § 16-579. For the reasons articu-
lated by the district court in its thorough decision, I would affirm its ruling
in favor of Arizona on the equal protection and Voting Rights Act chal-
lenges to Proposition 200’s voter registration requirement.
                      GONZALEZ v. ARIZONA                  17685
                                I.

   The fundamental rule of circuit law is that once a panel
decides a legal issue in a published opinion, that ruling binds
subsequent three-judge panels. The only instance when a
three-judge panel may depart from a prior published opinion
is if there has been “intervening” higher authority that is
“clearly irreconcilable with our prior circuit authority.” Mil-
ler, 335 F.3d at 900. And this instance is not truly an excep-
tion to the rule because it’s the intervening higher authority,
not the three-judge panel, that overrules the earlier opinion.
There are in fact no exceptions to law of the circuit, or at least
there weren’t until today.

   The majority holds that, although a published opinion is
binding generally, it doesn’t bind later panels in the same
case. For those panels, “[w]here no subsequent opinion has
relied on the prior published opinion for the proposition to be
overturned, . . . the law of the circuit doctrine does not pro-
hibit revising the prior opinion.” Maj. at 17668.

   This exception to the published opinion rule is irreconcil-
able with our recent en banc opinion in United States v.
Washington, 593 F.3d 790 (9th Cir. 2010) (en banc)
(“Washington IV”). In that case, the three-judge panel was
confronted with a conflict between a prior opinion in the same
case and another panel’s opinion in a different case. Because
it lacked the power to resolve the conflict, the three-judge
panel had to call the case en banc sua sponte. Sitting en banc,
we held:

    This appeal was initially argued to a three-judge
    panel, but the conflict in our precedent led us to
    rehear the matter en banc without awaiting a three-
    judge decision. See Atonio v. Wards Cove Packing
    Co., 810 F.2d 1477, 1478-79 (9th Cir. 1987) (en
    banc). This step was necessary because, even if the
    panel could have revisited Washington III under one
17686                 GONZALEZ v. ARIZONA
    of the exceptions to law of the case, see Jeffries v.
    Wood, 114 F.3d 1484, 1489 (9th Cir. 1997) (en
    banc), it still would have been bound by that pub-
    lished opinion as the law of the circuit, see, e.g., Old
    Person v. Brown, 312 F.3d 1036, 1039 (9th Cir.
    2002) (“[W]e have no discretion to depart from pre-
    cedential aspects of our prior decision in Old Person
    I, under the general law-of-the-circuit rule.”).

Washington IV, 593 F.3d at 798 n.9.

   Applying the Washington IV rule to this case is simple.
“[E]ven if” our three-judge panel were permitted to revisit the
prior panel’s opinion “under one of the exceptions to law of
the case,” we are “still . . . bound by that published opinion
as the law of the circuit” and have “no discretion to depart
from [it].” Id. (emphasis added). Washington IV—which
clearly holds that law of the circuit trumps law of the case—
forecloses the majority’s theory.

   The majority brushes aside Washington IV, relying instead
on three earlier cases, foremost Jeffries v. Wood, 114 F.3d
1484 (9th Cir. 1997) (en banc) (“Jeffries V”). There are two
problems with the majority’s reliance on Jeffries V, both of
which are fatal to the majority’s new rule. First, Jeffries V was
about law of the case, not law of the circuit. Jeffries V held
that the three-judge panel in Jeffries IV erred by failing to fol-
low Jeffries III, and based this conclusion on law of the case.
114 F.3d at 1492-93. The majority makes much of the fact
that the dissent in Jeffries V would have resolved the case on
law of the circuit grounds. Maj. at 17668. But it is peculiar
indeed to impute a holding to the majority on an issue it never
addressed, because it chose not to follow the contrary reason-
ing of the dissent. A dissent has no precedential value, United
States v. Ameline, 409 F.3d 1073, 1083 n.5 (9th Cir. 2005) (en
banc), and the majority is surely not obligated to address
every argument made there. It is obviously dangerous to infer
that the majority ruled on a matter as to which it never
                     GONZALEZ v. ARIZONA                   17687
expressed an opinion. By that peculiar reasoning, a majority
can be held to have decided an issue—and made it law of the
circuit—when it never said a word on the subject.

   The Jeffries V majority had very little to say about law of
the circuit, and what it did say totally undermines the majority
here: “The dissent seems to acknowledge that [the] law of the
circuit doctrine would preclude the Jeffries IV panel from
contradicting the Jeffries III opinion, thus reaching the same
result as the majority.” Id. at 1493 n.12. The majority some-
how manages to squeeze blood from a turnip.

   Second, to the extent Washington IV says something differ-
ent from Jeffries V, it is the most recent en banc opinion and
therefore clearly controls. See United States v. Heredia, 483
F.3d 913, 918-19 (9th Cir. 2007) (en banc) (recognizing that
a later en banc court may overrule an earlier en banc opinion).
The majority objects that Washington IV couldn’t have over-
ruled the “longstanding doctrine” that a three-judge panel may
overturn a prior panel’s published opinion under an exception
to the law of the case, maj. at 17669, but the doctrine in fact
never existed until today. It has no support in Jeffries V or any
other published opinion in our circuit.

   Take the other two cases the majority cites. See maj. at
17666 (citing Mendenhall v. NTSB, 213 F.3d 464, 469 (9th
Cir. 2000) (“Mendenhall II”); Tahoe-Sierra Pres. Council,
Inc. v. Tahoe Reg’l Planning Agency, 216 F.3d 764, 786-87
(9th Cir. 2000) (“Tahoe IV”)). The majority claims these
cases support its new rule because both reversed “a prior pub-
lished appellate opinion as clearly erroneous under the excep-
tions to the law of the case” doctrine. Maj. at 17666. But
neither case contradicted the prior panel’s legal ruling and
therefore never disturbed the law of the circuit. See United
States v. Johnson, 256 F.3d 895, 916 (9th Cir. 2001) (en banc)
(Kozinski, J., concurring) (a legal statement isn’t law of the
circuit unless “it is clear that a majority of the panel has
17688                     GONZALEZ v. ARIZONA
focused on the legal issue presented by the case before it and
made a deliberate decision to resolve the issue”).1

   The later Mendenhall panel reversed an award of market-
rate attorney’s fees, Mendenhall II, 213 F.3d at 469 & n.3, but
didn’t overturn the prior panel’s statement that “a request
[ for] attorneys’ fees at a reasonable market rate . . . . is appro-
priate where there is a showing of bad faith,” Mendenhall v.
NTSB, 92 F.3d 871, 876 (9th Cir. 1996). Rather, it realized
that the prior panel had mistakenly applied a statute awarding
attorney’s fees to litigants who prevailed in court to someone
who had prevailed in an administrative proceeding. Menden-
hall II, 213 F.3d at 469. Because the later panel applied the
correct statute, it had no occasion to disturb the prior panel’s
construction of the other statute.

   In Tahoe, both the earlier panel and the later panel applied
the rule that, in general, defendants must affirmatively plead
the statute of limitations in a filing with the court. See Levald,
Inc. v. City of Palm Desert, 998 F.2d 680, 686-87 (9th Cir.
  1
    While the majority ignores Johnson when exaggerating the preceden-
tial effect of two cases that didn’t alter the law of the circuit, it relies on
the Johnson concurrence in an attempt to characterize Washington IV’s
rule as the sort of “casual[ ]” statement “uttered in passing” that isn’t bind-
ing on later panels. Maj. at 17669-70. But the statement in Washington IV
was necessary to explain why the three-judge panel had to make a sua
sponte en banc call. 593 F.3d at 798 n.9. In any event, statements in en
banc opinions, as in Supreme Court opinions, must be taken far more seri-
ously than statements in three-judge panel opinions, even if they are not
strictly necessary to the result. See United States v. Baird, 85 F.3d 450,
453 (9th Cir. 1996) (“[W]e treat Supreme Court dicta with due deference
. . . .”). That’s because, like Washington IV’s rule, a statement in an en
banc opinion that’s not necessary to resolve the merits of the case often
“provides a supervisory function” to “three-judge panels and district
courts . . . . [and] thus constitutes authoritative circuit law.” Barapind v.
Enomoto, 400 F.3d 744, 751 n.8 (9th Cir. 2005) (en banc); see, e.g., Mil-
ler, 335 F.3d at 900; United States v. Hardesty, 977 F.2d 1347, 1348 (9th
Cir. 1992) (en banc) (per curiam); Atonio v. Wards Cove Packing Co., 810
F.2d 1477, 1478-79 (9th Cir. 1987) (en banc).
                          GONZALEZ v. ARIZONA                          17689
1993). The prior panel had held that the plaintiffs’ claims
weren’t time-barred because, by “[f]ailing to plead affirma-
tively” any statute of limitations other than an irrelevant one,
the defendants couldn’t then “rely on any other.” Tahoe-
Sierra Pres. Council, Inc. v. Tahoe Reg’l Planning Agency,
34 F.3d 753, 756 (9th Cir. 1994) (“Tahoe III”). On remand,
the defendants filed an answer that pled the correct statute of
limitations, and the later panel held that the claims were there-
fore time-barred. Tahoe IV, 216 F.3d at 788-89. Like Menden-
hall, the later panel’s putative reversal of a prior panel didn’t
alter a binding statement of circuit law.2

   Nor are Mendenhall and Tahoe the only cases on point. A
number of panel opinions hold that law of the circuit applies
to later panels in the same case. Old Person v. Brown, 312
F.3d 1036, 1039 (9th Cir. 2002), which Washington IV
quotes, is a good example. The Old Person panel explained
that it was bound by a prior opinion because “none of the
three exceptions” to law of the case applied, but it was careful
to point out that it also had “no discretion to depart from pre-
cedential aspects of our prior decision in Old Person I, under
the general law of the circuit rule.” Id.; see also Minidoka
Irrigation Dist. v. Dep’t of Interior, 406 F.3d 567, 574 (9th
Cir. 2005) (“[W]e are ‘bound by the opinion of the prior panel
as the law of the case. Also we have no discretion to depart
from precedential aspects of our prior decision in [Minidoka
I], under the general law-of-the circuit rule.’ ” (second alter-
ation in original)); accord Hilao v. Estate of Marcos, 103
F.3d 767, 772 (9th Cir. 1996) (“This court has twice rejected
these arguments in Estate I and Estate II. The published deci-
  2
    Tahoe IV said that it overturned Tahoe III’s “bare legal holding . . . that
the defendants forfeited the correct statute of limitations defense.” Tahoe
IV, 216 F.3d at 788. If that were truly Tahoe III’s holding, then the subse-
quent panel would have overturned law of the circuit. But it wasn’t. Tahoe
III said only that the defendants couldn’t rely on a statute of limitations
they hadn’t pled. Because the defendants hadn’t filed their answer, Tahoe
III couldn’t have considered whether they waived their statute of limita-
tions defense.
17690                     GONZALEZ v. ARIZONA
sions in those cases are both the controlling law of the circuit
and the law of this case.” (citations omitted)).

   Like Washington IV, these opinions explain that three-
judge panels are bound by prior panel opinions as law of the
circuit even if they’re not bound by those decisions as law of
the case. They also reconcile Mendenhall II and Tahoe IV
with our law of the circuit rule, for neither of those cases
departed from “precedential aspects” of the prior panel opin-
ions. But even if Mendenhall and Tahoe stood for what the
majority claims, our three-judge panel doesn’t have the power
to elevate them above Old Person, Minidoka or Hilao. If
“faced with such a conflict,” we “must call for en banc
review, which the court will normally grant unless the prior
decisions can be distinguished.” Atonio, 810 F.2d at 1479
(emphasis added).3
  3
    We’re not alone. Most of our sister circuits agree that three-judge pan-
els must follow prior published opinions in the same case as law of the cir-
cuit. See, e.g., Schiavo ex rel. Schindler v. Schiavo, 403 F.3d 1289, 1292
(11th Cir. 2005) (“Because our previous decision was published, the prior
panel precedent rule also applies to any holdings reached in the earlier
appeal.”); Swipies v. Kofka, 419 F.3d 709, 714 (8th Cir. 2005) (“[W]e held
in an earlier appeal in this case that Mr. Swipies possessed such an inter-
est. We are bound to follow this holding. It is not only the law of the case,
but the law of the circuit, i.e., a decision of another panel which only the
court en banc may overturn.” (citations omitted)); Af-Cap Inc. v. Republic
of Congo, 383 F.3d 361, 367 n.6 (5th Cir. 2004) (“The subsequent panel
would not only have to forego application of the law of the case doctrine,
but would also have to discard the well-established rule that circuit panels
are ‘bound by the precedent of previous panels absent an intervening . . .
case explicitly or implicitly overruling that prior precedent.’ ” (alteration
in original)); United States v. Alaw, 327 F.3d 1217, 1220 (D.C. Cir. 2003)
(“[T]hose issues are barred by law of the case doctrine . . . . In addition,
the law of the circuit doctrine applicable here prevents a new appellate
panel from declining to follow the legal rulings of the panel in a prior
appeal.”); Craft v. United States, 233 F.3d 358, 369 (6th Cir. 2000) (“Our
decisions in Craft I and in Cole are also law of the circuit. As we recently
stated, ‘One panel of this court may not overturn the decision of another
panel of this court—that may only be accomplished through an en banc
consideration of the argument.’ ”), overruled on other grounds by United
                          GONZALEZ v. ARIZONA                         17691
   Ultimately, this is all academic. There’s just no getting
around Washington IV’s holding that “even if” we were per-
mitted to revisit the prior panel’s opinion “under one of the
exceptions to law of the case,” we are “still . . . bound by that
published opinion as the law of the circuit” and have “no dis-
cretion to depart from [it].” 593 F.3d at 798 n.9. We can
debate the meaning of Jeffries all we want, but a unanimous
en banc court in Washington IV just resolved this very issue
against the majority’s position. The majority here audaciously
contradicts this en banc opinion.4

                                     II.

  Even if the majority were right that law of the circuit
doesn’t apply, Gonzalez I undisputedly binds us as law of the

States v. Craft, 535 U.S. 274 (2002); Irving v. United States, 162 F.3d
154, 160 (1st Cir. 1998) (en banc) (“In Irving I, a panel of this court
expressly defined the contours of the discretionary function exception.
From then on, that methodology represented both the law of the case and
the law of this circuit regarding the due application of the discretionary
function exception. . . . Indeed, when the United States asserted the discre-
tionary function defense in Irving II, the panel . . . took refuge in the law
of the circuit doctrine to dispense the argument . . . .” (citation omitted));
Pearson v. Edgar, 153 F.3d 397, 402 (7th Cir. 1998) (“Absent any inter-
vening Supreme Court decisions, Curtis and South-Suburban would be
binding precedent on this issue, and Curtis would also be the law of the
case.”). Such a lopsided verdict from our peers provides yet another rea-
son to question the wisdom of departing from our circuit’s well-settled
published opinion rule.
   4
     To the extent the majority suggests a three-judge panel can overrule
published opinions because they’re “clearly erroneous,” it also conflicts
with United States v. Contreras, 593 F.3d 1135 (9th Cir. 2010) (en banc).
Contreras reversed the portion of a panel opinion that had purported to
overrule several clearly erroneous published opinions because the panel
lacked authority to do so—even though the en banc court then adopted the
panel’s legal analysis. Id. at 1136; cf. State Oil Co. v. Khan, 522 U.S. 3,
20 (1997) (court of appeals was correct not to overrule an “infirm[ ]”
Supreme Court decision that it rightly predicted would be overturned by
the Supreme Court).
17692                 GONZALEZ v. ARIZONA
case. The majority tries in vain to wriggle out from under
Gonzalez I’s conclusion that the NVRA doesn’t preempt
Proposition 200 by invoking the “clearly erroneous” excep-
tion to the law of the case. Maj. at 17665-66. But the clearly
erroneous bar is a tall one to hurdle: If “it is plausible to find
that” the NVRA doesn’t preempt Proposition 200, “the hold-
ing in [Gonzales I] cannot be deemed clearly erroneous.” Les-
lie Salt Co. v. United States, 55 F.3d 1388, 1394 (9th Cir.
1995). “[I]t is incumbent upon [plaintiffs] to convince us not
only that the majority decision in [Gonzales I] was wrong, but
that it was clearly wrong.” Merritt, 932 F.2d at 1322; see also
Jeffries V, 114 F.3d at 1489. The majority fails to carry this
heavy burden and materially weakens the standard for all
future cases by pretending that it does.

                               A.

   According to the majority, the Gonzalez I panel’s “conclu-
sion was rooted in a fundamental misreading of the statute.”
Maj. at 17664 (emphasis added). “Reasoning from a funda-
mental misreading of the statute, the prior panel reached a
conclusion that was clear error.” Id. at 17665 (emphasis
added). But we don’t examine prior panels’ reasoning. We
must follow Gonzales I unless the “decision . . . is so clearly
incorrect that we are justified in refusing to regard it as law
of the case.” Merritt, 932 F.2d at 1321 (emphasis altered); see
Christianson v. Colt Indus. Operating Corp., 486 U.S. 800,
817 (1988) (“[T]he law of the case turns on whether a court
previously ‘decide[d] upon a rule of law’ . . . not on whether,
or how well, it explained the decision.” (second alteration in
original)).

   We might “scrutinize the merits . . . with greater care” if
Gonzalez I lacked any “analysis reflecting the authorities or
argument which led [it] to the rule [it reached].” United States
v. Houser, 804 F.2d 565, 568 (9th Cir. 1986). But the law of
the case doctrine doesn’t allow us to assume that poor reason-
ing begets clear error. Indeed, we’ve held that a panel’s fail-
                         GONZALEZ v. ARIZONA                         17693
ure to “expressly address [a] claim in its opinion”—and
corresponding failure to offer any reasons for its resolution of
that claim—isn’t clearly erroneous. Leslie Salt, 55 F.3d at
1393.

   A panel’s faulty reasoning doesn’t necessarily consign its
conclusion to the trash heap; most conclusions can be arrived
at through multiple chains of reasoning. And, although “pan-
els will occasionally find it appropriate to offer alternative
rationales,” Johnson, 256 F.3d at 914 (emphasis added),
they’re not required to do so. Thus, the existence of perceived
holes in a prior panel’s stated rationale doesn’t preclude the
possibility that the panel had unstated reasons leading it to the
same conclusion. It certainly doesn’t mean that the result the
panel reached is incorrect, as it may have reached the correct
result for the wrong reason.5 When we say that a panel’s hold-
ing is clearly wrong, what we’re talking about is the rule of
law it announces, not the method by which it adopts that rule.6

  This distinction doesn’t matter here because Gonzalez I
wasn’t clearly erroneous in either reasoning or result. Let’s
  5
     This principle also informs our review of district court judgments. “In
the review of judicial proceedings the rule is settled that, if the decision
below is correct, it must be affirmed, although the lower court relied upon
a wrong ground or gave a wrong reason.” Thos. P. Gonzalez Corp. v. Con-
sejo Nacional de Produccion de Costa Rica, 614 F.2d 1247, 1256 (9th Cir.
1980).
   6
     Focusing on a panel’s reasoning defeats the fundamental purpose of
law of the case doctrine—protecting the court and the parties from the bur-
den of repeated argument by pertinacious litigants—by encouraging the
parties to relitigate their case. See 18B Charles Alan Wright, Arthur R.
Miller & Edward H. Cooper, Federal Practice and Procedure § 4478 at
667 (2d ed. 2002). Such relitigation can slow decisionmaking to a glacial
pace, which is what happened to administrative agencies when judges
began to allow litigants to challenge the reasons the agencies gave for the
new regulations they proposed. See, e.g., Thomas O. McGarity, Some
Thoughts on “Deossifying” the Rulemaking Process, 41 Duke L.J. 1385,
1385-86, 1400-03 (1992); M. Elizabeth Magill, Agency Choice of Policy-
making Form, 71 U. Chi. L. Rev. 1383, 1390-91 & n.17 (2004).
17694                       GONZALEZ v. ARIZONA
start with Gonzales I’s statement that “[t]he NVRA mandates
that states either ‘accept and use the mail voter registration
form prescribed by the [Election Assistance Commission,]’
or, in the alternative, ‘develop and use [their own] form,’ as
long as the latter conforms to the federal guidelines.” Gonza-
lez I, 485 F.3d at 1050 (third alteration in original) (citations
omitted). The majority takes issue with this passage because
the NVRA requires states to accept and use both the federal
and state forms; ergo, Gonzalez I misconstrued the statute.
Maj. at 17664. But “the word ‘or’ is often used as a careless
substitute for the word ‘and’; that is, it is often used in phrases
where ‘and’ would express the thought with greater clarity.”
De Sylva v. Ballentine, 351 U.S. 570, 573 (1956). Indeed, it
is well recognized that “or” can have multiple meanings, with
the “exclusive or”—meaning one or the other but not both—
being largely useful in symbolic logic rather than common
parlance. Wikipedia, Exclusive or, http://en.wikipedia.org/
wiki/Exclusive_or (last visited Aug. 21, 2010).7
  7
   Wikipedia gives the following example to illustrate the difference
between the exclusive and the inclusive “or”:
      [I]t might be argued that the normal intention of a statement like
      “You may have coffee, or you may have tea” is to stipulate that
      exactly one of the conditions can be true. Certainly under many
      circumstances a sentence like this example should be taken as
      forbidding the possibility of one’s accepting both options. Even
      so, there is good reason to suppose that this sort of sentence is not
      disjunctive at all. If all we know about some disjunction is that
      it is true overall, we cannot be sure that either of its disjuncts is
      true. For example, if a woman has been told that her friend is
      either at the snack bar or on the tennis court, she cannot validly
      infer that he is on the tennis court. But if her waiter tells her that
      she may have coffee or she may have tea, she can validly infer
      that she may have tea. Nothing classically thought of as a dis-
      junction has this property. This is so even given that she might
      reasonably take her waiter as having denied her the possibility of
      having both coffee and tea.
      ....
         There are also good general reasons to suppose that no word
      in any natural language could be adequately represented by the
      binary exclusive “or” of formal logic.
                          GONZALEZ v. ARIZONA                        17695
   Legislatures—which presumably choose statutory language
with care—have used “or” conjunctively instead of as a dis-
junctive, exclusive “or.” See, e.g., Chemehuevi Tribe of Indi-
ans v. Fed. Power Comm’n, 420 U.S. 395, 417-18 (1975)
(“utilizing the surplus water or water power”); Swearingen v.
United States, 161 U.S. 446, 450 (1896) (“obscene, lewd or
lascivious”); see also Steven Wisotsky, How To Interpret
Statutes—Or Not: Plain Meaning and Other Phantoms, 10 J.
App. Prac. & Process 321, 326-27 (2009). And phrases that
seem obviously disjunctive like “or, in the alternative” are
sometimes used conjunctively. See H.W. Fowler, A Dictio-
nary of Modern English Usage 147 (2d ed. 1965). Thus, the
Gonzalez I panel could have meant that a state may rely
exclusively on the federal form or, in the alternative, also
develop a state form.8 This is a perfectly accurate description
of the NVRA.

   The majority protests that Gonzalez I couldn’t have used
“or” conjunctively because “such an interpretation would be
contrary to the prior panel’s logic.” Maj. at 17664. But it’s
only contrary to the majority’s interpretation of the prior
panel’s logic—and the majority begins its interpretation by
assuming Gonzalez I misread the statute. This is known as
begging the question. If we begin with the presumption that
unanimous three-judge panels don’t misread statutes, the “or”
can easily be construed conjunctively, to support the conclu-
sion that Gonzalez I interpreted the NVRA correctly. Cf.

Wikipedia, Exclusive or, http://en.wikipedia.org/wiki/Exclusive_or (last
visited Aug. 21, 2010).
   8
     Our own precedent shows that “and” and “or” can sometimes be used
interchangeably. For example, in MacDonald v. Pan American World Air-
ways, Inc., the majority construed “and” in a contract as “or” despite a par-
ticularly eloquent dissent. 859 F.2d 742, 744-45 (9th Cir. 1988); see id. at
746 (Kozinski, J., dissenting). MacDonald is law of the circuit as to the
“and” versus “or” issue and stands in the way of the majority’s claim that
the Gonzalez I panel somehow misread the statute.
17696                 GONZALEZ v. ARIZONA
United States v. Brown, 459 F.3d 509, 525 (5th Cir. 2006)
(“[I]f we begin with the assumption that [the defendant] is
guilty, the documents can be read to support that assumption.
But if we begin with the proper presumption that [he] is not
guilty . . . , we must conclude the evidence is insufficient
. . . .”).

   The other two quotes to which the majority points support
its argument even less. Gonzalez I states that section 1973gg-
7(b) of the NVRA “prohibits states from requiring that [their]
form be notarized or otherwise formally authenticated,” and
“permits states to ‘require[ ] such identifying information . . .
as is necessary to enable . . . election official[s] to assess the
eligibility of the applicant.’ ” 485 F.3d at 1050 (alterations in
original). The majority argues that Gonzalez I “misread” the
statute because the “portions of the NVRA that relate to the
Federal Form . . . are directed solely at the [Election Assis-
tance Commission], not the states.” Maj. at 17664. But these
instructions to the Commission do apply to the states through
section 1973gg-4(a)(2), which allows states to “develop and
use” their own form if it “meets all of the criteria stated in
section 1973gg-7(b).” Gonzalez I reads the statute correctly;
it is the majority here that is mistaken.

                               B.

   Even if the majority’s reasoning is wrong, its conclusion
that Gonzalez I clearly erred could still be correct if the
NVRA must be read to preempt state law. But it’s not enough
for the majority to find a construction of the statute it likes
better. After all, many statutes can plausibly be construed two
different ways, neither of which can be said to be clearly
wrong. See, e.g., Chevron, U.S.A., Inc. v. Natural Res. Def.
Council, 467 U.S. 837, 843 (1984) (“[I]f the statute is silent
or ambiguous with respect to the specific issue, the question
for the court is whether the agency’s answer is based on a per-
missible construction of the statute.” (emphasis added)). To be
clearly erroneous, the prior panel’s construction must be so
                     GONZALEZ v. ARIZONA                  17697
flawed that it could not pass the second step of the Chevron
test, had that construction been adopted by an administrative
agency. See id. at 844 (“[A] court may not substitute its own
construction of a statutory provision for a reasonable interpre-
tation made by the administrator of an agency.” (emphasis
added)).

   In this case, the text of the NVRA doesn’t “directly
address[ ] the precise question at issue,” id. at 843, namely
whether states can ask for supplemental proof of citizenship.
The statute says that “[e]ach State shall accept and use the
mail voter registration application form prescribed by the
[Election Assistance Commission].” 42 U.S.C. § 1973gg-
4(a)(1). It likewise requires “[a]cceptance of completed voter
registration application forms” at state and local government
offices, which must be transmitted “to the appropriate State
election official.” 42 U.S.C. § 1973gg-5(a)(4)(iii). The statute
doesn’t obviously prohibit supplemental state requirements,
and both preemptive and non-preemptive constructions of
“accept” and “use” are plausible. The prior panel’s construc-
tion thus easily passes the Chevron test.

   The majority believes that, by requiring states to “accept
and use” the federal form “for the registration of voters in
elections for Federal office,” 42 U.S.C. § 1973gg-4(a)(1), the
NVRA precludes states from imposing additional require-
ments. Maj. at 17654, 17665. But neither “accept” nor “use”
has such a preclusive meaning; it’s entirely possible to accept
and use something for a particular purpose, yet not have it be
sufficient to satisfy that purpose. Just go to any liquor store
that takes personal checks: They will happily accept and use
your check, but only after you provide ID showing that you’re
authorized to write it. A minute’s thought comes up with end-
less such examples: passport and visa; car registration and
proof of insurance; boarding pass and picture ID; eggs and
ham. Those who accept and use the former often also require
the latter.
17698                GONZALEZ v. ARIZONA
   The majority’s contention that “accept and use” must be
read preclusively “[i]n the context of the NVRA,” or “under
an Elections Clause framework,” maj. at 17665, is unconvinc-
ing because its understanding of “use” conflicts with that
word’s plain English meaning. As the Supreme Court has
observed,

    Webster’s defines “to use” as “[t]o convert to one’s
    service” or “to employ.” Webster’s New Interna-
    tional Dictionary 2806 (2d ed. 1950). Black’s Law
    Dictionary contains a similar definition: “[t]o make
    use of; to convert to one’s service; to employ; to
    avail oneself of; to utilize; to carry out a purpose or
    action by means of.” Black’s Law Dictionary 1541
    (6th ed. 1990). Indeed, over 100 years ago we gave
    the word “use” the same gloss, indicating that it
    means “ ‘to employ’ ” or “ ‘to derive service from.’ ”
    Astor v. Merritt, 111 U.S. 202, 213 (1884).

Smith v. United States, 508 U.S. 223, 228-29 (1993) (alter-
ations in original). To “use” an object is simply to derive ser-
vice from or utilize it. The NVRA doesn’t say that states must
treat the federal form as a complete application. It might pre-
clude a state from requiring an applicant to provide yet again
the information that is already on the federal form, but that’s
not the case here. There’s no question that Arizona accepts
and uses the federal form for the information contained in it.
Arizona only asks for proof of citizenship in addition to the
form in order to complete the registration process.

   Nor is the “accept and use” requirement necessarily con-
verted into a broad preemption provision by the NVRA’s gen-
eral statement that “notwithstanding any other Federal or
State law, in addition to any other method of voter registration
provided for under State law, each State shall establish proce-
dures to register to vote in elections for Federal office.” 42
U.S.C. § 1973gg-2(a); see maj. at 17654. That provision
merely requires states to implement the NVRA regardless of
                      GONZALEZ v. ARIZONA                  17699
any contrary legal authority. It doesn’t alter the substantive
scope of the statute.

   The only thing the NVRA expressly prohibits states from
requiring is “notarization or other formal authentication.” 42
U.S.C. § 1973gg-7(b)(3). The inclusion of a specific prohibi-
tion is a strong indication that other prohibitions weren’t
intended. See United States v. Cabaccang, 332 F.3d 622, 630
(9th Cir. 2003); see also U.S. Term Limits, Inc. v. Thornton,
514 U.S. 779, 793 n.9 (1995).

   Moreover, the NVRA expressly authorizes states to require
“such identifying information . . . as is necessary to enable the
appropriate State election official to assess the eligibility of
the applicant.” 42 U.S.C. § 1973gg-7(b)(1). This provision
can plausibly be read as authorizing the type of “identifying
information” that Arizona requires. The majority holds that
this passage is part of a comprehensive framework preventing
states from requiring proof of citizenship, but overlooks the
possibility that such proof may be “necessary to enable” Ari-
zona to assess eligibility. See maj. at 17652-53.

   Other states also require supplemental information and the
current National Voter Registration Form, available at
http://www.eac.gov/assets/1/Page/National Mail Voter Regis-
tration Form – English.pdf (“Registration Form”), seamlessly
accommodates them. The current form includes a box labeled
“ID Number” that directs applicants to “[s]ee item 6 in the
instructions for your state.” Item 6, in turn, catalogs the state-
by-state requirements each applicant must satisfy before the
state will “accept and use” the federal form. Just like Arizona,
many states require applicants to include proof of eligibility.
In Alabama, “[y]our social security number is requested.”
Registration Form at 3. Connecticut requires a “Connecticut
Driver’s License Number, or if none, the last four digits of
your Social Security Number.” Id. at 5. Hawaii tells appli-
cants that “[y]our full social security number is required. It is
used to prevent fraudulent registration and voting. Failure to
17700                 GONZALEZ v. ARIZONA
furnish this information will prevent acceptance of this appli-
cation.” Id. at 7. There’s more, but you get the idea. The
majority’s reading of the NVRA casts doubt on the voter reg-
istration procedures of many states in addition to Arizona.

   The simple truth is that nothing in the NVRA clearly super-
sedes Arizona’s supplemental registration requirements. To
get its way, the majority invents a broad rule of same-subject-
matter preemption, arguing that the NVRA “addresses pre-
cisely the same topic as Proposition 200 in greater specificity,
namely, the information that will be required to ensure that an
applicant is eligible to vote in federal elections,” such that its
“comprehensive regulation” of the voter registration proce-
dure “clearly subsumes Proposition 200’s additional docu-
mentary requirement.” Maj. at 17652-53. But, as the majority
acknowledges earlier in its opinion, the question under the
Elections Clause isn’t whether the two laws address “the same
topic,” but whether Arizona’s law “complements” rather than
conflicts with “the congressional procedural scheme.” Maj. at
17643 (citing Ex parte Siebold, 100 U.S. 371, 384 (1879));
see also Foster v. Love, 522 U.S. 67, 74 (1997) (state’s elec-
tion law is preempted “to [the] extent [that] it conflicts with
federal law”). There’s no conflict based on the text of the stat-
utes. Arizona gladly accepts and uses the federal form, it just
asks that voters also provide some proof of citizenship.

   Had Congress meant to enact a comprehensive code of
voter registration, it could have said so in the NVRA, but it
didn’t. Congress may have had the more modest goal of bal-
ancing ease of registration against each state’s interest in pro-
tecting its voting system. Had Congress explicitly prohibited
states from imposing additional requirements, then we could
plausibly conclude that Gonzalez I is clearly wrong. But it
didn’t, and therefore the majority has no authority under the
law of the case doctrine to “depart from [the] prior decision.”
Jeffries V, 114 F.3d at 1493.
                     GONZALEZ v. ARIZONA                   17701
                               C.

  The majority offers several of its own reasons for why the
NVRA preempts Arizona’s law. “If this court were consider-
ing the issue for the first time, [these] arguments might well
deserve closer consideration.” Leslie Salt, 55 F.3d at 1395.
But “at this point in the proceedings, [we] may address the
merits of [the] claims only so far as necessary to determine
whether the [Gonzalez I] court was clearly wrong.” Id. at
1394. None of the majority’s reasons meet this exacting stan-
dard.

   1. The majority claims that “allowing states to impose
their own requirements for federal voter registration . . .
would nullify the NVRA’s procedure for soliciting state input,
and aggrandize the states’ role in direct contravention of the
lines of authority prescribed by Section 7.” Maj. at 17654. But
Congress never granted much authority to the Election Assis-
tance Commission. The Commission can’t write many regula-
tions, 42 U.S.C. § 15329, can’t enforce the NVRA or the
regulations it writes, id. § 1973gg-9, and has no investigative
powers. That’s not the profile of an agency in charge of a
comprehensive regulatory scheme. Cf. CFTC v. Schor, 478
U.S. 833, 842 (1986) (O’Connor, J.) (“Congress empowered
the CFTC ‘to make and promulgate such rules and regulations
as . . . are reasonably necessary to effectuate any of the provi-
sions or to accomplish any of the purposes of [the CEA].’ ”
(alteration in original)). And Section 7 of the NVRA doesn’t
even prescribe lines of authority; it orders the Commission to
consult with the states when developing the federal form. See
id. § 1973gg-7(a). If anything, this indicates that Congress
didn’t want to aggrandize the Commission’s power over the
states. It certainly doesn’t “demonstrate a legislative intent to
limit States to a purely advisory role.” Cal. Coastal Comm’n
v. Granite Rock Co., 480 U.S. 572, 584 (1987) (O’Connor,
J.); see also Block v. Cmty. Nutrition Inst., 467 U.S. 340, 347
(1984) (O’Connor, J.).
17702                GONZALEZ v. ARIZONA
   Nor is the majority right to rely on the letter from the Elec-
tion Assistance Commission telling Arizona that its proof-of-
citizenship requirement violates the NVRA. Maj. at 17654.
We don’t give deference to administrative agencies on the
question of preemption. See Wyeth v. Levine, 129 S. Ct. 1187,
1200-01 (2009) (“In such cases, the Court has performed its
own conflict determination, relying on the substance of state
and federal law and not on agency proclamations of pre-
emption.”). Even if we did, we wouldn’t defer in this case,
because an informal letter clearly lacks “the force of law.”
United States v. Mead Corp., 533 U.S. 218, 226-27 (2001).
Determining whether the NVRA preempts Arizona’s proof-
of-citizenship requirement begins and ends with the statute.

   For the same reason, the majority’s claims that states
shouldn’t be able to make an “end-run around the [Election
Assistance Commission]’s consultative process,” maj. at
17655, and that allowing states to supplement the federal form
“would make the [Commission’s] procedure for consultation
. . . an empty exercise,” id. at 17665, beg the question of
whether the Commission can bind the states. Congress may
have intended to grant states the power to supplement federal
rules despite the Commission’s objection. Cf. Cuomo v.
Clearing House Ass’n, 129 S. Ct. 2710, 2717 (2009) (states
can enforce state fair-lending laws that OCC tried to pre-
empt). If Congress intended to give states this power to dis-
agree, then Arizona hasn’t made an end-run at all.

   2. The majority relies on the fact that the NVRA “ad-
dresses precisely the same topic as Proposition 200 in greater
specificity, namely, the information that will be required to
ensure that an applicant is eligible to vote in federal elec-
tions.” Maj. at 17652. But the NVRA’s text never states that
it’s the exclusive authority on this issue, or that the federal
form must be “a fully sufficient means of registering to vote
in federal elections.” Maj. at 17665. It’s perfectly plausible
that the NVRA would have set the minimum information
states must require, prohibited one specific type of require-
                     GONZALEZ v. ARIZONA                 17703
ment (formal authentication) and established a consultative
process for developing a national form. Such broad, flexible
guidance is far from a definitive regulatory scheme. More-
over, if the statute permits zero deviation from the federal
form, why permit states to develop their own forms at all?
The only development needed would be photocopying the
federal form.

   Relatedly, the majority claims that because the NVRA pro-
hibits requiring “notarization or other formal authentication,”
42 U.S.C. § 1973gg-7(b)(3), Congress must have intended to
prohibit states from imposing any supplemental requirements.
Maj. at 17653. But Congress doesn’t disguise general pro-
scriptions of everything as specific proscriptions of one nar-
row thing. See Whitman v. Am. Trucking Ass’n, 531 U.S. 457,
468 (2001) (“Congress . . . [doesn’t] hide elephants in mouse-
holes.”). Nor would permitting Arizona to require proof of
citizenship free it to violate the NVRA’s ban on requiring for-
mal notarization. Maj. at 17653. Refusing to enforce an
unwritten ban hardly weakens the force of an express prohibi-
tion.

   3. The majority devotes much time to making the case that
“the thrust of the NVRA is to increase federal voter registra-
tion by streamlining the registration process.” Maj. at 17651;
see id. at 17644-52. It spends endless pages reviewing the his-
tory of voting laws, id. at 17644-46, discussing congressional
hearings on the general problem of voter participation, id. at
17646, and reviewing the many operative parts of the NVRA,
maj. at 17646-52. But the majority’s lengthy disquisition on
history and purpose only highlights the absence of any textual
support for its conclusion that Congress meant to increase
voter registration by prohibiting state-imposed supplemental
requirements. To the extent we rely on purpose at all, we
should focus on the purposes codified in the statute rather
than our guesses based on reading the tea leaves of history
and context. See Exxon Mobil Corp. v. Allapattah Servs., Inc.,
545 U.S. 546, 568 (2005).
17704                GONZALEZ v. ARIZONA
  The NVRA’s four purposes are:

    (1) to establish procedures that will increase the
    number of eligible citizens who register to vote in
    elections for Federal office;

    (2) to make it possible for Federal, State, and local
    governments to implement this subchapter in a man-
    ner that enhances the participation of eligible citi-
    zens as voters in elections for Federal office;

    (3) to protect the integrity of the electoral process;
    and

    (4) to ensure that accurate and current voter registra-
    tion rolls are maintained.

42 U.S.C. § 1973gg(b) (emphasis added). Congress thus told
us that it was concerned with maximizing the registration of
“eligible” voters, in addition “to protect[ing] the integrity of
the electoral process” and “ensur[ing] that accurate and cur-
rent voter registration rolls are maintained.” Id. None of these
purposes is served when individuals who are not citizens reg-
ister to vote. See John v. United States, 247 F.3d 1032,
1036-37 (9th Cir. 2001) (“We must not ‘interpret federal stat-
utes to negate their own stated purposes.’ ”). The majority
never explains why a statute enacted to “protect the integrity
of the electoral process” and “ensure” that voter rolls are “ac-
curate” must preclude states from confirming that those who
wish to register are, in fact, eligible to vote.

                             ***

   The majority distorts two major areas of law before it even
reaches the merits. It creates an unprecedented exception to
our law of the circuit rule, trampling underfoot a newly
minted en banc opinion. The majority also makes a mess of
the law of the case analysis by taking issue with a prior
                    GONZALEZ v. ARIZONA                17705
panel’s reasoning, not its conclusion. And, as to the merits,
the panel comes nowhere close to proving that Gonzalez I’s
interpretation of the National Voter Registration Act was
wrong, much less clearly wrong. Few panels are able to upset
quite so many apple carts all at once. Count me out.
