                    FOR PUBLICATION

   UNITED STATES COURT OF APPEALS
        FOR THE NINTH CIRCUIT

 BISHOP PAIUTE TRIBE,                            No. 15-16604
                 Plaintiff-Appellant,
                                                   D.C. No.
                     v.                         1:15-cv-00367-
                                                   GEB-JLT
 INYO COUNTY; WILLIAM LUTZE,
 Inyo County Sheriff; THOMAS
 HARDY, Inyo County District                       OPINION
 Attorney,
              Defendants-Appellees.

         Appeal from the United States District Court
             for the Eastern District of California
        Garland E. Burrell, Jr., District Judge, Presiding

             Argued and Submitted April 21, 2017
                  San Francisco, California

                       Filed July 19, 2017

   Before: Sidney R. Thomas, Chief Judge, Mary H.
Murguia, Circuit Judge, and Michael M. Baylson, * District
                          Judge.

                  Opinion by Judge Murguia

    *
      The Honorable Michael M. Baylson, United States District Judge
for the Eastern District of Pennsylvania, sitting by designation.
2           BISHOP PAIUTE TRIBE V. INYO COUNTY

                          SUMMARY **


         Federal Question Jurisdiction / Ripeness

    The panel reversed the district court’s dismissal on
jurisdictional grounds of an action brought by an Indian
tribe, seeking a declaration regarding the tribe’s right to
conduct law enforcement on its reservation.

    The panel held that because the tribe had alleged
violations of federal common law, it had adequately pleaded
a federal question providing the district court with subject
matter jurisdiction under 28 U.S.C. § 1331.

    The panel held that the case was constitutionally and
prudentially ripe because there was an actual and imminent
threat to a concrete interest of the tribe, and the case was fit
for judicial decision. In addition, the case was not moot.

    The panel remanded the case to the district court for
further proceedings.




    **
       This summary constitutes no part of the opinion of the court. It
has been prepared by court staff for the convenience of the reader.
           BISHOP PAIUTE TRIBE V. INYO COUNTY                3

                         COUNSEL

Dorothy A. Alther (argued), California Indian Legal
Services, Escondido, California; Jasmine Andreas,
California Indian Legal Services, Bishop, California; for
Plaintiff-Appellant.

John D. Kirby (argued), Law Offices of John D. Kirby, San
Diego, California; Marshall S. Rudolph, Inyo County
Counsel, Independence, California; for Defendants-
Appellees.


                         OPINION

MURGUIA, Circuit Judge:

    The Bishop Paiute Tribe (the “Tribe”) seeks a
declaration that they have the right to “investigate violations
of tribal, state, and federal law, detain, and transport or
deliver a non-Indian violator [encountered on the
reservation] to the proper authorities.” Before reaching this
issue, the district court dismissed the case on jurisdictional
grounds, concluding that the case presents no actual case or
controversy. On appeal, we are also asked to assess whether
the district court had subject matter jurisdiction over this
case. Because questions of federal common law can serve
as the basis of federal subject matter jurisdiction pursuant to
28 U.S.C. § 1331, and because this case presents a definite
and concrete dispute that is ripe and not moot, we reverse
and remand for further proceedings.
4            BISHOP PAIUTE TRIBE V. INYO COUNTY

                        I. BACKGROUND

A. Factual History 1

    The Tribe is a federally recognized Indian Tribe with an
875-acre reservation near the city of Bishop in the County of
Inyo, California. The Tribe exercises powers of self-
government through its governing body, the Tribal Council,
which consists of five officers elected from the general tribal
membership. The Tribe has approximately 1,800 persons
living on the reservation and runs a casino that allegedly has
received approximately 450,000 visitors.

    The Tribe has established civil but not criminal tribal law
and has enacted three civil ordinances that are relevant to this
case: a Nuisance Ordinance, a Trespass Ordinance, and a
Tribal Public Safety Ordinance. Section 201 of the Tribal
Public Safety Ordinance permits the tribal court to issue and
enforce protective orders for the purposes of preventing
violence or threatening acts. Section 202 of the Tribal Public
Safety Ordinance permits the tribal court to give full faith
and credit to valid protective orders issued by a state or
another tribe’s tribal court.

    In 2009, the Tribe established a Tribal Police
Department (“Tribal PD”). Since that time, the Tribal PD
has responded to several hundred calls. Many of the
responses are completed along with the Inyo County
Sheriff’s Department (“ICSO”). The Tribal PD employs

    1
      We take the following facts from the allegations in the first
amended complaint (“FAC”), which we must assume to be true. See
Daniels-Hall v. Nat’l Educ. Ass’n, 629 F.3d 992, 998 (9th Cir. 2010)
(explaining that at this stage of the proceedings, “[w]e accept as true all
well-pleaded allegations of material fact, and construe them in the light
most favorable to the non-moving party”).
           BISHOP PAIUTE TRIBE V. INYO COUNTY                5

three officers and a Chief of Police. Each officer must meet
various qualification requirements, including having two
years of law enforcement experience and completing a law
enforcement training class. The Tribal PD patrols the
reservation, enforces tribal ordinances, and conducts
investigations. Tribal PD General Order 3.1 states that a
Tribal PD officer may need to detain an Indian or non-Indian
individual to secure the scene, prevent the suspect from
leaving the scene, or for officer safety. Tribal PD officers
are also permitted to detain non-Indians who are suspected
of committing criminal acts on the reservation and to transfer
such individuals to outside law enforcement. Non-Indians
are to be turned over to outside law enforcement as soon as
possible.

    On December 24, 2014, Tribal PD Officer Daniel
Johnson (“Johnson”) received an on-reservation call from a
tribal member reporting that the tribal member’s non-Indian
ex-wife was violating the tribal member’s tribal and state
protective orders by being at his home and causing a
disturbance. Johnson notified the ICSO about the incident
and responded to the call. Tribal and local law enforcement
knew the suspect well; Tribal PD had responded to 11 calls
involving the suspect, and ICSO had previously arrested the
suspect twice for violating the state protective order.

    Once Johnson arrived at the scene, he approached the
suspect, who was sitting in her vehicle. Johnson informed
the suspect that she was violating tribal and state court
protective orders and that she needed to leave. The suspect
became angry and verbally abusive. Johnson informed her
that he was going to detain her for violating the protective
ordinances and that she would be cited for violating the tribal
nuisance and trespass ordinances. Johnson repeatedly
ordered the suspect to exit the vehicle, but she did not. As
6         BISHOP PAIUTE TRIBE V. INYO COUNTY

Johnson attempted to remove her from the vehicle, the
suspect kicked him. In response, Johnson removed his Taser
and warned the suspect that if she did not comply, Johnson
would deploy his Taser. The suspect did not comply, and
Johnson applied his Taser to her.

    Moments after Johnson deployed his Taser, an ICSO
deputy arrived. Several neighbors, who had gathered around
Johnson and the suspect, were verbally abusive toward
Johnson. The ICSO deputy requested assistance from the
police department of the nearby city of Bishop, California,
because he and Johnson were outnumbered and the
neighbors were hostile. Johnson finally removed the suspect
from the vehicle and handcuffed her. Soon thereafter, a
Bishop City Police Detective and ICSO Acting Lieutenant
and Detective arrived at the scene and conducted an
investigation. The officers ultimately released the suspect,
because her ex-husband did not want her to be arrested.
Johnson, however, cited the suspect for trespass, nuisance,
and violating the tribal and state protective orders.

    Before leaving the scene, the ICSO detective noticed a
small abrasion and some redness on the suspect’s abdominal
area and asked the suspect if she was injured. Johnson asked
the suspect if she wanted an ambulance to respond, and the
suspect declined the offer. The following week, the ICSO
conducted an investigation into the December 24 incident
that was submitted to the Inyo County district attorney’s
office. On January 5, 2015, the Inyo County district attorney
filed a felony complaint against Johnson charging him with
assault with a stun gun, false imprisonment, impersonating a
public officer, and battery.

    On January 6, 2015, ICSO Sheriff William Lutze
(“Sheriff Lutze”) sent a “Cease and Desist Order” to the
Tribe ordering Tribal PD to “cease and desist all law
           BISHOP PAIUTE TRIBE V. INYO COUNTY                7

enforcement of California statutes.” The order stated that
ICSO had repeatedly told Tribal PD that its officers had been
illegally exercising state police powers and that Tribal PD
officers “do NOT have any legal authority, notwithstanding
Bishop Paiute tribal authority, to enforce any state or federal
laws within or outside tribal property.”           The order
documented several instances of the Tribal PD allegedly
illegally exercising law enforcement authority, including the
December 24, 2014 incident with Johnson. ICSO ordered
Tribal PD to immediately:

       (A) cease and desist the unlawful exercise of
       California peace officer authority both within
       and outside tribal property and (B) cease and
       desist possessing firearms outside tribal
       property (e.g. court appearances) and
       (C) provide this office with prompt written
       assurance within ten (10) days that Tribal
       Police will cease and desist from further acts
       as explained in this correspondence.

       If Tribal Police does not comply with this
       cease and desist order within this time period,
       be advised that Tribal Police employees will
       be subjected to arrest and criminal
       prosecution for applicable charges as well as
       Penal      Code       § 538d       (Fraudulent
       Impersonation of a Peace Officer).

(emphasis in original).

   The Tribe responded to the cease and desist order on
January 15, 2015. The Tribe noted that it disagreed with
ICSO’s presentation of the facts and interpretation of
applicable law but, as a show of good faith, the Tribe agreed
8         BISHOP PAIUTE TRIBE V. INYO COUNTY

that its officers would “not exercise California peace officer
authority on or off the reservation” and would “carry their
firearms only on the Bishop Paiute Indian Reservation.” The
Tribe did not suggest that its officers would refrain from
exercising their inherent authority as interpreted by the
Tribe. The Tribe further noted the importance of Tribal PD
officers being “allowed to perform their legal duties without
fear or expectation of criminal prosecution” and therefore
requested a meeting with ICSO to address the matters
identified in the cease and desist letter.

B. Procedural History

    The Tribe brought this action against Inyo County,
Sheriff Lutze, and Inyo County District Attorney Thomas
Hardy (collectively “Defendants”).         Attached to the
operative first amended complaint (“FAC”) were several
exhibits, including Johnson’s felony arrest warrant and
criminal complaint, the cease and desist order, various tribal
ordinances, Tribal PD officer job descriptions, and Tribal PD
policies and procedures.

    In its FAC, the Tribe requested that the district court
clarify the Tribe’s rights with respect to the ongoing dispute
with the Defendants. In particular, the Tribe sought
declarations that:

       [1] Defendants’ actions of arresting and
       charging Tribal Officer Johnson and future
       threat of criminal prosecution of the Tribe’s
       police officers, violates federal common law
       and directly interferes with the Tribe’s
       inherent authority to maintain a police
       department and protect public safety on its
       Reservation.
           BISHOP PAIUTE TRIBE V. INYO COUNTY                9

       [2] [T]he Tribe’s police officers have the
       authority on its Reservation to stop, restrain,
       investigate violations of tribal, state and
       federal law, detain, and transport or deliver a
       non-Indian violator to the proper authorities.
       By carrying out these federally authorized
       actions, the Tribe’s duly authorized law
       enforcement officers are not impersonating a
       state officer nor is their restraint,
       investigation and detention of a non-Indian,
       in compliance with provisions of the Indian
       Civil Rights Act, an “arrest” for purposes of
       a state criminal charge of false imprisonment.

The Tribe also sought to enjoin Defendants from arresting,
criminally charging, interfering with, or threatening Tribal
PD officers who exercise their lawful duties. Finally, the
Tribe sought attorney fees and costs.

    The three defendants each separately moved to dismiss
the FAC. After the motions were fully briefed, counsel for
Defendants filed a declaration stating that he recently
learned that the Tribe had responded to ICSO’s cease and
desist order. Defendants’ counsel attached the Tribe’s letter
and stated that the letter “appears to address and resolve the
directives of the Sheriff’s letter” and that the letter “raises
the issue of mootness of this litigation, and subject matter
jurisdiction, as well as accompanying justiciability, and
further speaks to and underscores the issue of ripeness, as
well as the issue of existence of an actual case or
controversy.” The Tribe filed an “Opposition” to the
declaration, arguing that the Tribe’s case “is not moot and
presents a case and controversy.”
10           BISHOP PAIUTE TRIBE V. INYO COUNTY

    On July 13, 2015, the district court, stating that it could
consider jurisdictional issues sua sponte, dismissed the FAC
for lack of a justiciable case or controversy. Bishop Paiute
Tribe v. Inyo Cty., No. 1:15-CV-00367-GEB-JTL, 2015 WL
4203986, at *1, *4 (E.D. Cal. July 13, 2015). The Tribe
timely appealed. 2

                 II. STANDARD OF REVIEW

    We review de novo a district court’s order dismissing a
case for lack of subject matter jurisdiction, lack of ripeness,
or for mootness. Maronyan v. Toyota Motor Sales, U.S.A.,
Inc., 658 F.3d 1038, 1039 (9th Cir. 2011) (subject matter
jurisdiction); Mfr’d Home Cmtys. Inc. v. City of San Jose,
420 F.3d 1022, 1025 (9th Cir. 2005) (ripeness); Foster v.
Carson, 347 F.3d 742, 745 (9th Cir. 2003) (mootness).




     2
       Under Federal Rule of Civil Procedure 41(b), dismissals for lack
of jurisdiction are generally without prejudice and are therefore not final
appealable orders. However, determining whether a ruling is final and
therefore appealable under 28 U.S.C. § 1291 requires “a practical rather
than a technical” analysis. Gillespie v. U.S. Steel Corp., 379 U.S. 148,
152 (1964) (citation omitted). We have held that “[a] ruling is final for
purposes of § 1291 if it (1) is a full adjudication of the issues, and
(2) clearly evidences the judge’s intention that it be the court’s final act
in the matter.” Elliott v. White Mountain Apache Tribal Court, 566 F.3d
842, 846 (9th Cir. 2009) (citation omitted). Here, we have little doubt
that the judge intended his order to be his final act in this case. The order
and the docket state that “this action is DISMISSED for lack of
jurisdiction and shall be closed.” Bishop Paiute Tribe, 2015 WL
4203986, at *4. The district court thereafter issued a Judgment. And the
district court did not hint at future proceedings or the filing of a second
amended complaint. We therefore conclude that the district court’s order
was a final appealable order.
          BISHOP PAIUTE TRIBE V. INYO COUNTY               11

                    III. DISCUSSION

    The district court’s order and the parties’ briefing raise
two main questions. First, Defendants argue on appeal that
the court lacks subject matter jurisdiction because the FAC
does not present a question of federal law. Second, the Tribe
argues that the district court improperly dismissed the case
on ripeness grounds because the district court erred in
concluding that the Tribe brought a pre-enforcement
challenge against a “law” without pleading a concrete plan
to violate the law. Relatedly, the Tribe argues that the
district court improperly dismissed the case on mootness
grounds because the district court erroneously concluded
that the Tribe had agreed to comply with ICSO’s cease and
desist order. We agree with the Tribe on all counts: we have
subject matter jurisdiction over the Tribe’s claims, which are
ripe and not moot.

A. Subject Matter Jurisdiction

    “The party asserting jurisdiction bears the burden of
establishing subject matter jurisdiction.” In re Dynamic
Random Access Memory (DRAM) Antitrust Litig., 546 F.3d
981, 984 (9th Cir. 2008). “Dismissal for lack of subject
matter jurisdiction is appropriate if the complaint,
considered in its entirety, on its face fails to allege facts
sufficient to establish subject matter jurisdiction.” Id. at
984–85. Under 28 U.S.C. § 1331, federal “district courts
shall have original jurisdiction of all civil actions arising
under the Constitution, laws, or treaties of the United
States.” Questions of federal common law present a federal
question that can serve as the basis of federal subject matter
jurisdiction pursuant to 28 U.S.C. § 1331. Illinois v. City of
Milwaukee, 406 U.S. 91, 100 (1972) (“[Section] 1331
jurisdiction will support claims founded upon federal
common law as well as those of a statutory origin.”); see also
12           BISHOP PAIUTE TRIBE V. INYO COUNTY

Gila River Indian Cmty. v. Henningson, Durham &
Richardson, 626 F.2d 708, 714 (9th Cir. 1980) (citing
Illinois, 406 U.S. at 100 (noting that this principle applies in
the context of federal Indian law)).

    The Tribe alleged in the FAC that the district court had
jurisdiction based on 28 U.S.C. §§ 1331, 1362, 2201, and
2202. Of these provisions, the most important is 28 U.S.C.
§ 1331, because the Tribe clearly alleges violations of
federal common law. The Tribe specifically alleges that
“[t]he Defendants’ arrest and charging of Tribal officer
Johnson . . . violates federal common law.” The Tribe
alleges that federal common law grants the Tribe the
authority to “investigate violations of tribal, state, and
federal law, detain, and transport or deliver a non-Indian
violator to the proper authorities.” 3 Because the Tribe has
alleged violations of federal common law, the Tribe has
adequately pleaded a federal question that provides federal
courts with subject matter jurisdiction pursuant to 28 U.S.C.
§ 1331. See Gila River, 626 F.2d at 714.

    Defendants offer several unpersuasive arguments that
the FAC fails to adequately establish subject matter
jurisdiction. First, Defendants argue that “the Tribe
completely fails to identify” which law this case arises
under. Defendants’ assertion is simply wrong. In its FAC,

     3
       Though we need not reach the merits of this claim to conclude that
the Tribe has properly alleged federal subject matter jurisdiction, we note
that the Tribe has at least a colorable claim for relief. See, e.g., Duro v.
Reina, 495 U.S. 676, 697 (1990) (superseded by statute on other
grounds); Ortiz-Barraza v. United States, 512 F.2d 1176, 1179 (9th Cir.
1975) (holding that “Indian tribes possess an inherent sovereignty,”
which includes the power “to exclude trespassers who have violated state
or federal law by delivering the offenders to the appropriate authorities”).
            BISHOP PAIUTE TRIBE V. INYO COUNTY                     13

the Tribe provided a long list of Supreme Court and other
relevant case law regarding the Tribe’s alleged inherent
authority to exercise jurisdiction over non-Indians on a
reservation. 4 The Tribe explicitly alleged that Defendants
violated federal common law under this line of cases.

    Second, Defendants argue that the Indian Law
Enforcement Reform Act of 1990 (“ILERA”), 25 U.S.C.
§§ 2801 et seq., and its accompanying federal regulations,
25 C.F.R. §§ 12.21 et seq., have displaced the federal
common law upon which the FAC relies. Congress can
displace federal common law through legislation. Am. Elec.
Power Co. v. Connecticut, 564 U.S. 410, 423 (2011). “The
test for whether congressional legislation excludes the
declaration of federal common law is simply whether the
statute speaks directly to the question at issue.” Id. at 424
(citation and alterations omitted). Defendants argue that the
ILERA speaks directly “to the question which is at issue here
– that of tribal law enforcement officers enforcing federal
law on reservations.”

    However, Defendants confuse what the Tribe is seeking
in this case. Defendants argue that the ILERA speaks
directly to the question of whether and to what extent tribal
law enforcement officers can enforce federal law. That
question is distinct from what the Tribe actually seeks: a
declaration that the Tribe may investigate violations of
tribal, state, and federal law and detain and deliver a non-
Indian potential violator to state law enforcement authorities.
The Tribe is not seeking a declaration that it can enforce

    4
      For example, the Tribe cites Duro, Montana v. United States,
450 U.S. 544 (1981), Oliphant v. Suquamish Indian Tribe, 435 U.S. 191
(1978), Ortiz-Barraza v. United States, 512 F.2d 1176 (9th Cir. 1975),
and Williams v. Lee, 358 U.S. 217 (1959).
14         BISHOP PAIUTE TRIBE V. INYO COUNTY

federal law on the reservation or that it can prosecute
violators of federal or state criminal law. Essentially,
Defendants fail to show how the ILERA comprehensively or
directly addresses the inherent tribal police authority that the
Tribe seeks to exercise over non-Indians. As Defendants
themselves point out, the ILERA establishes a program
through which the Bureau of Indian Affairs offers training to
tribal law enforcement officers who wish to exercise federal
peace officer powers. The Tribe is not seeking such
authority in this case. Moreover, Defendants point to no case
in which a court has concluded that ILERA displaces the
alleged federal common law right of tribes to detain and
deliver to the proper authorities a non-Indian suspected of
violating tribal, state, or federal law on tribal property.

    For these reasons, we hold that the FAC raises a federal
question that provides federal courts with subject matter
jurisdiction pursuant to 28 U.S.C. § 1331.

B. Justiciability

    Pursuant to Article III of the U.S. Constitution, federal
courts can only adjudicate live cases or controversies. See
Thomas v. Anchorage Equal Rights Comm’n, 220 F.3d 1134,
1138 (9th Cir. 2000) (“Our role is neither to issue advisory
opinions nor to declare rights in hypothetical cases, but to
adjudicate live cases or controversies consistent with the
powers granted the judiciary in Article III of the
Constitution.”). In this case, the two most relevant
justiciability doctrines are ripeness and mootness.

     1. Ripeness

    Ripeness is an Article III doctrine designed to ensure that
courts adjudicate live cases or controversies and do not
“issue advisory opinions [or] declare rights in hypothetical
            BISHOP PAIUTE TRIBE V. INYO COUNTY                     15

cases.”    Id.    A proper ripeness inquiry contains a
constitutional and a prudential component. Id.

        a. Constitutional Ripeness

    For a case to be ripe, it must present issues that are
“definite and concrete, not hypothetical or abstract.” Id. at
1139 (citation omitted). Constitutional ripeness is often
treated under the rubric of standing because “ripeness
coincides squarely with standing’s injury in fact prong.” Id.
at 1138 (“Sorting out where standing ends and ripeness
begins is not an easy task.”). 5 For a plaintiff to meet the
injury-in-fact prong of standing, the plaintiff must
demonstrate “an invasion of a legally protected interest
which is (a) concrete and particularized and (b) actual or
imminent, not conjectural or hypothetical.” Lujan, 504 U.S.
at 560 (citations omitted).

     Here, the Tribe identifies its legally protected interest as
its “inherent sovereign authority to restrain, detain, and
deliver to local authorities a non-Indian on tribal lands that
is in violation of both tribal and state law.” This interest is
certainly concrete and particularized. See Oklevueha Native
Am. Church of Hawaii, Inc. v. Holder, 676 F.3d 829, 836–
37 (9th Cir. 2012). As the matter currently stands, the Tribe
has been ordered to cease and desist exercising what it
believes to be its proper inherent authority. The Tribe has
already seen one of its officers arrested and prosecuted based
on Defendants’ interpretation of the Tribe’s lawful authority.
See id. (finding that plaintiffs alleged a concrete injury
because the statute at issue had already been enforced

    5
      The “irreducible constitutional minimum of standing” includes
(1) an injury in fact; (2) causation; and (3) redressability. Lujan v.
Defenders of Wildlife, 504 U.S. 555, 560 (1992).
16        BISHOP PAIUTE TRIBE V. INYO COUNTY

against them, “thereby eliminating any concerns that
Plaintiffs’ fear of enforcement is purely speculative”). Since
the Tribe covers the legal costs of defending its Tribal PD
officers from prosecution, this dispute has cost the Tribe
money. And Defendants’ interference with the Tribe’s
alleged inherent authority has, according to Tribe, interfered
with the Tribe’s ability to maintain peace and security on the
reservation. See id.

    Moreover, in addition to the actual arrest and prosecution
of Johnson, the ICSO’s cease and desist letter credibly
threatens imminent future prosecutions if the Tribe fails to
abide by ICSO’s demand. While generalized threats of
prosecution do not confer constitutional ripeness, a genuine
threat of imminent prosecution does. Thomas, 220 F.3d at
1139. To determine whether a genuine threat of imminent
prosecution exists,

       we look to whether the plaintiffs have
       articulated a concrete plan to violate the law
       in question, whether the prosecuting
       authorities have communicated a specific
       warning or threat to initiate proceedings, and
       the history of past prosecution or
       enforcement under the challenged statute.

Id. (citation omitted). Here, the Inyo County district
attorney’s office has already prosecuted one Tribal PD
officer, and ICSO communicated a specific threat of
additional prosecutions.

   Because the arrest and ongoing prosecution of Johnson
and the cease and desist order threatening future
prosecutions demonstrate that the threat to the Tribe’s
concrete interest is actual and imminent, we hold that the
           BISHOP PAIUTE TRIBE V. INYO COUNTY                17

Tribe’s FAC alleges an injury in fact that meets the
requirements of constitutional ripeness.

       b. Prudential Ripeness

    Our evaluation of “the prudential aspects of ripeness” is
“guided by two overarching considerations: ‘the fitness of
the issues for judicial decision and the hardship to the parties
of withholding court consideration.’” Thomas, 220 F.3d at
1141 (quoting Abbott Labs. v. Gardner, 387 U.S. 136, 149
(1967) overruled on other grounds by Califano v. Sanders,
430 U.S. 99 (1977)). “Prudential considerations of ripeness
are discretionary.” Id. at 1142. In determining whether a
case is fit for judicial decision, this court has looked to
whether the case presents a “concrete factual situation” or
purely legal issues. Id. at 1141–42; see also San Diego Cty.
Gun Rights Comm. v. Reno, 98 F.3d 1121, 1132 (9th Cir.
1996).

    Here, the FAC presents a detailed factual account of the
underlying disputes in this case, including the arrest and
ongoing prosecution of Johnson and the ongoing dispute
over the scope of the Tribe’s lawful sovereign authority.
Withholding the court’s consideration and resolution of
these disputes creates multiple hardships for the Tribe,
including ongoing legal costs, intrusions on the Tribe’s
ability to keep the peace and security of the reservation,
misunderstanding and confusion surrounding the ability of
the Tribe and Tribal PD to enforce tribal laws and prevent
lawlessness on the reservation, and potentially an unlawful
limitation on the Tribe’s inherent sovereign powers. This
case is clearly fit for judicial decision. See Oklevueha,
676 F.3d at 837–38 (finding prudential ripeness because
“seizure of Plaintiffs’ marijuana presents a concrete factual
scenario that demonstrates how the laws, as applied, infringe
18         BISHOP PAIUTE TRIBE V. INYO COUNTY

Plaintiffs’ constitutional rights” (citation and alterations
omitted)).

    The Tribe has presented a prudentially ripe case or
controversy. Because the case is constitutionally ripe as
well, we hold that the district court erred by concluding that
this case was not ripe.

     2. Mootness

    The final issue is whether this case is moot in light of the
Tribe’s response letter, in which ICSO contends that the
Tribe agreed to abide by the cease and desist letter. The
district court relied on the Tribe’s letter in concluding that
there was no ongoing controversy.

    A federal court lacks jurisdiction to hear a case that is
moot. Carson, 347 F.3d at 745. A case is moot “where no
actual or live controversy exists.” Id. (citation omitted). “If
there is no longer a possibility that an appellant can obtain
relief for his claim, that claim is moot and must be dismissed
for lack of jurisdiction.” Id. (citation omitted). Mootness
has been described as “standing set in a time frame: The
requisite personal interest that must exist at the
commencement of the litigation (standing) must continue
throughout its existence (mootness).” Id. (citation omitted).

    Here, the district court erred by concluding that the
Tribe’s response letter to the cease and desist order mooted
any ongoing controversy. The letter makes clear that the
Tribe disagreed with ICSO’s letter and order. The Tribe
specifically stated “[w]e disagree with your presentation of
the facts, and your interpretations of applicable law.” But
the Tribe agreed to address ICSO’s concerns “as a show of
good faith and to keep the peace.” This letter in no way
demonstrates that the controversy over the scope of the
          BISHOP PAIUTE TRIBE V. INYO COUNTY               19

Tribe’s lawful sovereign authority was put to rest. In fact,
the Tribe requested further meetings with ICSO to address
ICSO’s concerns. And the Tribe specifically noted the
importance of Tribal PD officers being “allowed to perform
their legal duties without fear or expectation of criminal
prosecution.” The district court’s conclusion that the Tribe’s
response letter mooted all controversies between the parties
was erroneous. See Carson, 347 F.3d at 745 (explaining that
mootness occurs “where no actual or live controversy exists”
(citation omitted)).

                    IV. CONCLUSION

    Because the district court has subject matter jurisdiction
over claims involving federal common law and because the
Tribe’s case is ripe and not moot, we REVERSE and
REMAND for further proceedings.
