                               In the

    United States Court of Appeals
                 For the Seventh Circuit
No. 18-1343

UNITED STATES OF AMERICA,
                                                  Plaintiff-Appellee,

                                 v.


BLAIR COOK,
                                              Defendant-Appellant.


        Appeal from the United States District Court for the
                   Western District of Wisconsin.
        No. 3:17-cr-00048 — James D. Peterson, Chief Judge.



   ON REMAND FROM THE UNITED STATES SUPREME COURT


   Before FLAUM, MANION, and ROVNER, Circuit Judges.
   ROVNER, Circuit Judge. A jury convicted Blair Cook of being
an unlawful user of a controlled substance (marijuana) in
possession of a firearm and ammunition. See 18 U.S.C.
§§ 922(g)(3) (proscribing possession of firearm by unlawful
user of controlled substance), 924(a)(2) (specifying penalties for
one who “knowingly” violates section 922(g)). Cook appealed
2                                                     No. 18-1343

his conviction, contending that the statute underlying his
conviction is facially vague, that it improperly limits his Second
Amendment right to possess a firearm, and that the district
court did not properly instruct the jury as to who constitutes an
unlawful user of a controlled substance. We affirmed Cook’s
conviction. United States v. Cook, 914 F.3d 545 (7th Cir. 2019).
The Supreme Court subsequently held in Rehaif v. United States,
139 S. Ct. 2191, 2194, 2200 (2019), that the knowledge element
of section 924(a)(2) requires the government to show that the
defendant knew not only that he possessed a firearm, but that
he belonged to the relevant category of persons barred from
possessing a firearm. Consistent with the prior case law of this
court, the superseding indictment in this case did not allege,
nor the jury instructions advise the jury that it must find, that
Cook knew he was an unlawful user of a controlled substance.
Cook’s petition for a writ of certiorari was pending at the time
that Court was considering Rehaif, and Cook had suggested
that if the Court in Rehaif expanded the knowledge requirement
of section 924(a)(2) to include knowledge of one’s status, the
Court ought to remand his case for further proceedings.
Petition for Writ of Certiorari at 25–26, Cook v. United States,
No. 18-9707 (U.S. June 12, 2019).1 The Court subsequently
granted Cook’s petition, vacated our decision sustaining his
conviction, and remanded for reconsideration in light of Rehaif,
as Cook had asked it to do. Cook v. United States, 140 S. Ct. 41
(Oct. 7, 2019). Upon reconsideration, we now reincorporate our
previous decision, with minor modifications, rejecting Cook’s


1
  Available at https://www.supremecourt.gov/search.aspx?filename=/
docket/docketfiles/html/public/18-9707.html (visited July 28, 2020)
No. 18-1343                                                         3

vagueness and Second Amendment challenges to section
922(g)(3) along with his objection to the jury instruction on
who constitutes an unlawful user of a controlled substance. But
in light of Rehaif, we conclude that Cook is entitled to a new
trial.
                                  I.
    On May 25, 2017, officers of the Madison, Wisconsin police
department conducted a traffic stop of the car that Cook was
driving. When officers approached the car and spoke with
Cook, they noticed a strong odor of marijuana emanating from
the car. Apart from the possibility that Cook was driving under
the influence of marijuana, Cook was also driving on a sus-
pended license and with a license plate missing from his
vehicle, so the officers decided to detain him and ordered him
to step out of the vehicle. Officer Matthew Wentzel removed a
loaded, .40-caliber Glock Model 23 pistol from a holster under
Cook’s shoulder. The gun had an extended capacity magazine
with a total of 19 bullets within it when Cook was stopped.
Cook was transported to the police station for further question-
ing. During a recorded interview at the station, Cook acknowl-
edged to Wentzel that “I’ve been smoking weed since I was
like 14" (a period of nearly ten years), that he did so because “it
really mellows me out,” and that he had smoked two “blunts”
earlier that day. R. 22-1 at 2–3.2 As Judge Peterson would later
note in denying Cook’s motion for a new trial, “The way Cook
phrased his statement suggests not merely that he smoked


2
  “Blunt” is a street term for a cigar from which the tobacco has been
removed and replaced with marijuana. R. 56 at 22.
4                                                  No. 18-1343

weed the first time when he was 14, but that it was a regular
activity since then.” R. 73 at 2. On prodding from the police,
Cook ultimately produced a packet from his groin area
containing a half ounce of marijuana.
    Cook had purchased the firearm from Max Creek Outdoors
in Oregon, Wisconsin on April 2, 2017. At the time of the
purchase, he was required to complete a Firearms Transaction
Record (Form 4473) promulgated by the Bureau of Alcohol,
Tobacco, Firearms, and Explosives (“ATF”). On that form,
Cook answered “No” to the question, “Are you an unlawful
user of, or addicted to, marijuana or any depressant, stimulant,
narcotic drug, or any other controlled substance?” Directly
under that question the reader of the form was admonished,
“Warning: The use or possession of marijuana remains unlaw-
ful under Federal law regardless of whether it has been
legalized or decriminalized for medical or recreational pur-
poses in the state where you reside.” Gov. Trial Ex. No. 1.
    A grand jury subsequently charged Cook with two offenses:
knowingly possessing in or affecting commerce a firearm and
ammunition as an “unlawful user” of marijuana, in violation of
sections 922(g)(3) and 924(a)(2), and knowingly making a false
statement (that he was not an unlawful user of marijuana) on
the ATF form in connection with his purchase of a firearm and
ammunition, in violation of section 924(a)(1)(A). R. 7.
   Cook moved to dismiss both counts of the indictment on
the ground that the term “unlawful user” of a controlled
substance found in section 922(g)(3) is unconstitutionally
vague. The district court denied the motion. R. 21 at 2–3.
No. 18-1343                                                     5

    The district court subsequently gave the following instruc-
tion to the jury as to who constitutes an “unlawful user” of
marijuana:
     The defendant was an unlawful user of marijuana
     if he used marijuana on a regular and ongoing basis
     for a period of time that began before and continued
     through the date of the charged offense. The govern-
     ment is not required to prove that the defendant was
     under the influence of marijuana when he filled out
     the Firearms Transaction Record or when he pos-
     sessed the firearm. The government is not required
     to prove that the defendant used marijuana on any
     particular day, or within a certain number of days of
     when he committed the charged offenses.
R. 44 at 8; R. 56 at 70–71 (emphasis in original). The defense
rejected the government’s offer to include an additional
sentence in this instruction advising the jury that a one-time use
of marijuana is insufficient to render the defendant an “unlaw-
ful user” within the meaning of section 922(g)(3). R. 87 at 17.
    Following a one-day trial, a jury convicted Cook on the
possession charge but was unable to reach a verdict on the false
statement charge, which the district court dismissed without
prejudice. R. 46, 53. The district court denied Cook’s Rule 33
motions for a new trial (R. 73) and ordered Cook to serve a
four-year term of probation in lieu of any term of imprison-
ment (R. 76).
6                                                         No. 18-1343

                                  II.
    We begin our reconsideration with the charges Cook raised
prior to the Supreme Court’s decision in Rehaif. Although we
conclude in section III below that Rehaif entitles Cook to a new
trial, these issues are not moot and our analysis remains
relevant to the proceedings on remand.
    Section 922(g)(3) of the Criminal Code provides in relevant
part that “[i]t shall be unlawful for any person … who is an
unlawful user of or addicted to any controlled substance (as
defined in section 102 of the Controlled Substances Act (21
U.S.C. § 802)) … to … possess in or affecting commerce, any
firearm or ammunition … .” Marijuana is a Schedule I con-
trolled substance, see 21 U.S.C. § 812(c)(10), and because the
Glock pistol Cook purchased from Max Creek Outdoors had
previously traveled in interstate commerce (it was manufac-
tured in Smyrna, Georgia), section 922(g)(3) forbade Cook’s
possession of the gun at the time of the May 2017 traffic stop
provided that he qualified as an “unlawful user” of marijuana,
which the jury necessarily found that he did. Section 924(a)(2)
in turn provides that anyone who “knowingly” violates section
922(g) shall be imprisoned for up to 10 years.3
    Cook challenges his conviction pursuant to section 922(g)(3)
on three grounds: (1) the statute is facially vague as to who
constitutes an “unlawful user” of a controlled substance; (2) the
statute violates his Second Amendment right to possess a


3
   Cook possessed (and was charged with possessing) ammunition as well
as a firearm, but for the sake of simplicity, we shall refer only to the
firearm.
No. 18-1343                                                             7

firearm; and (3) the jury instruction defining “unlawful user”
was inadequate. For the reasons that follow, we find none of
these arguments to be persuasive.
A. Facial vagueness challenge to section 922(g)(3)
    Cook contends that section 922(g)(3) is vague on its face,
such that his conviction violates the Fifth Amendment’s due
process clause. The void-for-vagueness doctrine requires that
a criminal statute define an offense with sufficient clarity that
an ordinary person has fair notice of what conduct is prohib-
ited and so as to avoid arbitrary and discriminatory enforce-
ment. See, e.g., Skilling v. United States, 561 U.S. 358, 402–03, 130
S. Ct. 2896, 2927–28 (2010); United States v. Sylla, 790 F.3d 772,
774–75 (7th Cir. 2015). “What renders a statute vague is not the
possibility that it will sometimes be difficult to determine
whether the incriminating fact it establishes has been proved;
but rather the indeterminacy of precisely what that fact is.”
United States v. Williams, 553 U.S. 285, 306, 128 S. Ct. 1830, 1846
(2008).
    The general practice, outside of the First Amendment
context,4 has been to consider the purported vagueness of a
statute in light of the facts of the particular case—i.e., as
applied—rather than in the abstract. See, e.g., Maynard v.
Cartwright, 486 U.S. 356, 361, 108 S. Ct. 1853, 1857–58 (1988);
United States v. Johnson, 875 F.3d 360, 370 (7th Cir. 2017). This


4
  When a statute implicates activities protected by the First Amendment,
there is a special concern that free speech and expression not be chilled.
See Broadrick v. Oklahoma, 413 U.S. 601, 611–12, 93 S. Ct. 2908, 2915–16
(1973).
8                                                    No. 18-1343

means, of course, that a litigant challenging the statute ordi-
narily must show that it is vague as applied to him; and if the
statute undoubtedly applies to his conduct, he will not be heard
to argue that the statute is vague as to one or more hypotheti-
cal scenarios. See Holder v. Humanitarian Law Project, 561 U.S. 1,
18–19, 130 S. Ct. 2705, 2718–19 (2010) (quoting Village of
Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S. 489,
495, 102 S. Ct. 1186, 1191 (1982)); Broadrick v. Oklahoma, supra
n.4., 413 U.S. at 610–11, 93 S. Ct. at 2915 (collecting cases).
    Nonetheless, the Supreme Court has on a number of
occasions entertained facial challenges to criminal statutes that
do not implicate First Amendment concerns. See, e.g., Skilling,
561 U.S. at 402–14, 130 S. Ct. at 2927–34 (honest services fraud);
City of Chicago v. Morales, 527 U.S. 41, 52–64, 119 S. Ct. 1849,
1857–63 (1999) (loitering by gang members in public places);
Lanzetta v. New Jersey, 306 U.S. 451, 453–58, 59 S. Ct. 618,
619–21 (1939) (gang participation); United States v. L. Cohen
Grocery Co., 255 U.S. 81, 89–93, 41 S. Ct. 298, 300–01 (1921)
(price gouging). As we noted in United States v. Jones, 689 F.3d
696 (7th Cir. 2012), abrogated on other grounds, Johnson v. United
States, 135 S. Ct. 2551 (2015), the common thread uniting these
cases with facial challenges in the First Amendment context
appears to be a concern (or at least a colorable contention) that
the challenged statute “simply has no core” and lacks “any
ascertainable standard for inclusion and exclusion, ”id. at 703
(quoting Smith v. Goguen, 415 U.S. 566, 578, 94 S. Ct. 1242, 1249
(1974)). Such a standardless statute poses a trap for the person
acting in good faith, who is given no guidepost by which he
can divine what sort of conduct is prohibited. See Colautti v.
Franklin, 439 U.S. 379, 395–96, 99 S. Ct. 675, 685–86 (1979),
No. 18-1343                                                        9

overruled in part on other grounds, Webster v. Reproductive Health
Servs., 492 U.S. 490, 109 S. Ct. 3040 (1989). The concern is
heightened when the statute contains no mens rea requirement,
Colautti, 439 U.S. at 395, 99 S. Ct. at 685–86, and the uncertainty
as to exactly what is proscribed “threatens to inhibit the
exercise of constitutionally protected rights,” id. at 391, 99 S. Ct.
at 683. See also Morales, 527 U.S. at 55, 119 S. Ct. at 1858.
    The statutory prohibition at issue here does not present
such concerns. True enough, section 922(g)(3) does implicate
Cook’s Second Amendment right to possess a gun. But the
prohibition is not a strict liability offense requiring no mens rea,
as in Colautti. By virtue of the separate penalties provision
found in section 924(a)(2), a violation of section 922(g)(3) must
be knowing – that is, the defendant must have knowledge of
the facts that constitute the offense. E.g., Dixon v. United States,
548 U.S. 1, 5, 126 S. Ct. 2437, 2441 (2006) (“unless the text of the
statute dictates a different result, the term ‘knowingly’ merely
requires proof of knowledge of the facts that constitute the
offense”) (quoting Bryan v. United States, 524 U.S. 184, 193, 118
S. Ct. 1939, 1946 (1998)); see Humanitarian Law Project, 561 U.S.
at 21, 130 S. Ct. at 2720 (“the knowledge requirement of the
statute further reduces any potential for vagueness, as we have
held with respect to other statutes containing a similar require-
ment”) (collecting cases); United States v. Johnson, 911 F.3d 849,
853 (7th Cir. 2018) (word “knowingly” cures any potential
vagueness in challenged condition of supervised release) (citing
Screws v. United States, 325 U.S. 91, 102, 65 S. Ct. 1031, 1036
(1945)). And as Rehaif has now clarified, that knowledge
requirement extends to the particular status that renders a
defendant’s possession of a firearm unlawful. 139 S. Ct. at 2194,
10                                                   No. 18-1343

2200. Moreover, there is, as our decision in United States v.
Yancey, 621 F.3d 681 (7th Cir. 2010) (per curiam) makes clear,
a readily appreciable core of conduct prohibited by the
particular subsection of 922(g) at issue here.
    Yancey construes the term “unlawful user,” as used in
section 922(g)(3), to mean one who regularly or habitually
ingests a controlled substance in a manner other than as
prescribed by a physician. Id. at 682. Our opinion adds that
such use must be contemporaneous with the defendant’s
possession of a gun. Id. at 687 (collecting cases); see also United
States v. Grap, 403 F.3d 439, 446 (7th Cir. 2005) (adopting same
contemporaneity requirement for purposes of U.S.S.G.
§ 2K2.1(a)(6), which specifies the base offense level for
“prohibited person” convicted of firearms offense) (collecting
cases). Yancey set forth this interpretation of section 922(g)(3)
in the course of rejecting a Second Amendment challenge to the
statute. Noting the well-established link between chronic drug
use and violence, we concluded that section 922(g)(3)’s ban on
gun possession by those who regularly engage in illegal drug
use was substantially related to the important government
interest in preventing violent crime. 621 F.3d at 685–86. We
must take into account Yancey’s gloss on the statute in evaluat-
ing Cook’s vagueness claim. See Skilling, 561 U.S. at 405, 130 S.
Ct. at 2929 (“It has long been our practice, … before striking a
federal statute as vague, to consider whether the prescription
is amenable to a limiting construction.”); Pleasureland Museum,
Inc. v. Beutter, 288 F.3d 988, 995–96 (7th Cir. 2002); Waldron v.
McAtee, 723 F.2d 1348, 1354 (7th Cir. 1983).
No. 18-1343                                                     11

    Cook is thus not in a position to claim that the statute is so
indefinite as to inhibit the legitimate exercise of Second
Amendment rights. Whatever doubt there might be at the
margins as to conduct potentially reached by section 922(g)(3),
there can be no doubt as to the core of conduct that the statute
(as construed by Yancey) proscribes: the possession of a firearm
by an individual engaged in the regular, non-prescribed use of
a controlled substance. Indeed, it would appear that Cook’s
conduct—possession of a firearm in the midst of a nearly ten-
year period of marijuana use—epitomizes that core, which may
explain why Cook is so keen to challenge the statute on its face
rather than as applied.
     Cook nonetheless suggests that the Supreme Court’s recent
decision in Johnson authorizes his facial vagueness challenge,
regardless of whether the statute is vague as applied to his
particular conduct. Johnson declared the (now defunct) residual
clause of the Armed Career Criminal Act (“ACCA”) to be
impermissibly vague without requiring the defendant to first
show that the clause was vague as applied to him. 135 S. Ct. at
2563. The ACCA specifies an enhanced sentence of 15 years to
life for one convicted of a firearms offense if the defendant has
three or more prior convictions for either a “serious drug
offense” or a “violent felony.” 18 U.S.C. § 924(e)(1). As relevant
here, the statute defines “violent felony” to mean a crime
punishable by a year or more in prison which “is burglary,
arson, or extortion, involves use of explosives, or otherwise
involves conduct that presents a serious potential risk of physical
injury to another[.]” § 924(e)(2)(B)(ii) (emphasis ours). The Court
previously had construed section 924(e)(2)(B)(ii) to require a
sentencing court to employ a categorical approach focusing on
12                                                   No. 18-1343

the generic version of an offense (that is, what the elements of
the offense minimally require in the abstract), rather than the
defendant’s actual conduct, in deciding whether his prior
conviction qualified as a violent felony. See Taylor v. United
States, 495 U.S. 575, 602, 110 S. Ct. 2143, 2160 (1990). In view of
the categorical inquiry mandated by Taylor, two aspects of the
residual clause we have italicized led the Supreme Court in
Johnson to conclude that this clause was impermissibly vague:
(1) after postulating the archetypal version of the crime, one
had to decide how much risk of physical injury was posed by
that idealized version of the offense; and (2) one also had to
consider how much risk of injury was required to render an
offense violent as compared with the offenses expressly
identified in the statute (burglary, arson, extortion, and
offenses involving the use of explosives). 135 S. Ct. at 2557–58.
Both inquiries were plagued by uncertainty, as evidenced by
both the Court’s own demonstrated inability in a series of prior
residual clause cases to articulate a “principled and objective
standard” for identifying crimes that present a serious risk of
physical injury, id. at 2558, as well as the “numerous splits
among the lower federal courts,” where the clause had proved
“nearly impossible to apply consistently,” id. at 2560 (quoting
Chambers v. United States, 555 U.S. 122, 133, 129 S. Ct. 687, 694
(2009) (Alito, J., concurring in judgment)). “Nine years’
experience trying to derive meaning from the residual clause
convinces us that we have embarked upon a failed enterprise,”
the Court concluded. “Each of the uncertainties in the residual
clause may be tolerable in isolation, but ‘their sum makes a task
for us which at best could be only guesswork.’” Id. (quoting
No. 18-1343                                                   13

United States v. Evans, 333 U.S. 483, 495, 68 S. Ct. 634, 641
(1948)).
    In declaring the residual clause to violate the due process
clause, the Court expressly rejected the government’s conten-
tion that an otherwise vague statute is constitutional so long as
“there is some conduct that clearly falls within the provision’s
grasp.” Id. at 2561. While acknowledging that statements in
some of its opinions could be read to support such a rule, the
Court emphasized that its prior holdings squarely contradicted
such a practice. Id. at 2560–61. Simply because it is possible to
envision some factual scenarios that would violate an
ambiguously-worded statute is not enough to rescue that
statute from a vagueness challenge, the Court made clear. Id. at
2561.
    The Court was also at pains to emphasize, however, that
simply because a criminal statute uses qualitative language to
articulate a liability standard does not mean that the statute is
impermissibly vague, especially when the statute under
scrutiny calls upon the court to apply that standard to a
concrete set of facts. Id. at 2561; see also id. at 2558.
     As a general matter, we do not doubt the constitu-
     tionality of laws that call for the application of a
     qualitative standard such as “substantial risk” to
     real-world conduct; “the law is full of instances
     where a man’s fate depends on his estimating rightly
     … some matter of degree,” Nash v. United States, 229
     U.S. 373, 377, 33 S. Ct. 780 (1913). The residual
     clause, however, requires application of the “serious
     potential risk” standard to an idealized ordinary
14                                                              No. 18-1343

      case of the crime. Because “the elements necessary to
      determine the imaginary ideal are uncertain both in
      nature and degree of effect,” this abstract inquiry
      offers significantly less predictability than one
      “[t]hat deals with the actual, not with an imaginary
      condition other than the facts.” International Har-
      vester Co. of America v. Kentucky, 234 U.S. 216, 223, 34
      S. Ct. 853 (1914).
135 S. Ct. at 2561.
    It is not clear how much Johnson—and the Court’s follow-on
decision in Sessions v. Dimaya, 138 S. Ct. 1204 (2018), which
invalidated similar language in the Immigration and National-
ity Act—actually expand the universe of litigants who may
mount a facial challenge to a statute they believe is vague. Not
surprisingly, Cook contends that Johnson permits any defen-
dant who can postulate doubts as to what particular conduct a
criminal statute does or does not reach to pursue a facial
challenge to that statute, without having to show that there is
any real question as to whether his own conduct is proscribed.
It is true that Johnson puts to rest the notion—found in any
number of pre-Johnson cases—that a litigant must show that the
statute in question is vague in all of its applications in order to
successfully mount a facial challenge.5 135 S. Ct. at 2561. And,


5
  See, e.g., United States v. Salerno, 481 U.S. 739, 745, 107 S. Ct. 2095, 2100
(1987) (“A facial challenge to a legislative Act is, of course, the most
difficult challenge to mount successfully, since the challenger must
establish that no set of circumstances exists under which the Act would
be valid.”); Johnson, 135 S. Ct. at 2574, 2581 (Alito, J., dissenting); Hegwood
                                                                  (continued...)
No. 18-1343                                                                  15

as we have mentioned, Johnson likewise rejects the notion that
simply because one can point to some conduct that the statute
undoubtedly would reach is alone sufficient to save it from a
vagueness challenge. Id. So Cook has those aspects of Johnson
going for him. But so much of the Court’s analysis in Johnson
deals with a statute that is in key respects sui generis. In
particular, it was the categorical approach called for by the
ACCA’s residual clause—requiring courts to look not at the
actual conduct underlying the defendant’s prior conviction but
rather at the archetypal version of the offense, and then to
consider whether the risk of injury posed by that version was
sufficient to render the crime violent—which the court found to
be particularly vexing. Id. at 2557–58. Assessing the degree of
risk posed by an idealized “typical” version of an offense was
significantly different, as the Court emphasized, from looking
at the risks posed by a set of actual, concrete facts. Id. at 2558;
see also Dimaya, 138 S. Ct. at 1214–16; Copeland v. Vance, 893
F.3d 101, 110–11 n.2 (2d Cir. 2018) (noting unique context of
Johnson).
    Cook’s appeal, by contrast, presents a much more routine
vagueness challenge that highlights some imprecision in the
statutory language and posits uncertainty as to whether the
statute might apply to certain hypothetical facts. But section
922(g)(3) does not call for the court to engage in any abstract
analysis; it calls on the court to apply the statutory prohibition


5
   (...continued)
v. City of Eu Claire, 676 F.3d 600, 604 (7th Cir. 2012); Sherman ex rel. Sherman
v. Koch, 623 F.3d 501, 520 (7th Cir. 2010); Schor v. City of Chicago, 576 F.3d
775, 781 (7th Cir. 2009).
16                                                             No. 18-1343

to a defendant’s real-world conduct. See United States v. Davis,
139 S. Ct. 2319, 2327 (2019) (“a case-specific approach would
avoid the vagueness problems that doomed the statutes in
Johnson and Dimaya”). Moreover, there is, as we have dis-
cussed, a readily appreciable core of conduct that the statute
reaches: If one regularly uses marijuana or another controlled
substance other than as directed by a physician, he may not
possess a firearm so long as the use persists. Consequently,
citizens who wish to exercise their Second Amendment rights
and law enforcement officials alike have reasonable notice of
what is prohibited. This is not a “hopelessly indeterminate”
statute (Cook Br. 13) that leaves everyone to guess what
conduct is legal and what conduct is proscribed.6 The statute,
as construed by Yancey, does incorporate a qualitative liability
standard, and one can posit, as Cook does, hypothetical
scenarios which present close questions as to whether an


6
    We recognize that a liability standard turning on the regularity of a
particular activity can in some instances present a vagueness problem. See
Whatley v. Zatecky, 833 F.3d 762 (7th Cir. 2016) (finding statute
impermissibly vague where it specified enhanced sentence for individual
possessing controlled substance within 1000 feet of “youth program
center,” defined as any building that provides youth-oriented programs
or services “on a regular basis”). In contrast to Whatley, the statute at issue
here is not a strict-liability provision, and one’s liability under section
922(g)(3) turns on the regularity of one’s own conduct rather than the
activity occurring in a building that may exhibit no indicia of what
programs and services are provided therein and how often. One who uses
a controlled substance necessarily knows how often he does so. See United
States v. Purdy, 264 F.3d 809, 812 (9th Cir. 2001) (“Purdy’s [regular, years-
long] drug use … was sufficient to put him on notice that he fell within the
statutory definition of ‘unlawful [drug] user.’”).
No. 18-1343                                                    17

individual’s use of a controlled substance is generally unlawful,
whether it qualifies as regular and ongoing under Yancey,
and/or whether that use is sufficiently contemporaneous with
his or her possession of a firearm. But in contrast with the
ACCA’s residual clause, there is no judicial history of courts
struggling to appreciate what particular conduct Congress
meant to reach with section 922(g)(3) or to apply the statutory
terms to varying sets of facts. The uniform rejection of as-
applied vagueness challenges to section 922(g)(3) by itself
suggests that it is not anything like the sort of problematic
statute the Court confronted in Johnson. See United States v.
Bramer, 832 F.3d 908, 909–10 (8th Cir. 2016) (per curiam); United
States v. Edwards, 540 F.3d 1156, 1162 (10th Cir. 2008); United
States v. Patterson, 431 F.3d 832, 836 (5th Cir. 2005); United
States v. Purdy, supra n.6, 264 F.3d at 812–13. And simply
because it may sometimes be difficult to determine if an
individual’s drug use meets section 922(g)(3)’s standard for
liability does not signify that the statute is impermissibly
vague, given that there is no doubt as to the essence of what
the statute forbids: the possession of a firearm by one who is
engaged in the regular and ongoing use of a controlled sub-
stance other than as prescribed by a doctor. See Williams, supra,
553 U.S. at 306, 128 S. Ct. at 1846.
   For these reasons, we are not convinced that Cook is
entitled to mount a facial vagueness challenge to section
922(g)(3). Johnson did not alter the general rule that a defendant
whose conduct is clearly prohibited by a statute cannot be the
one to make a facial vagueness challenge. United States v.
Westbrooks, 858 F.3d 317, 325–26 (5th Cir. 2017) (collecting
cases), cert. granted & judgment vacated on other grounds, 138 S.
18                                                   No. 18-1343

Ct. 1323 (2018). Cook’s conduct, if anything, undoubtedly falls
within the obvious core of conduct proscribed by the statute.
Per his statement at the police station, he had been using
marijuana for almost ten years and he had smoked two blunts
on the day of his arrest; and the police officers who stopped his
vehicle and took him into custody noted a strong odor of
marijuana emanating from the interior and that Cook himself
reeked of the substance. These facts no doubt explain why
Cook has declined to pursue an as-applied vagueness challenge
to section 922(g)(3): it would surely fail. See United States v.
Jackson, 280 F.3d 403, 406 (4th Cir. 2002) (addressing facts
similar to those presented here) (“While we do not doubt that
the exact reach of the statute is not easy to define, we agree
with the government that this is not a borderline case. … Given
the evidence, Jackson violated the plain meaning of the
statute.”).
    Cook’s attempt to challenge section 922(g)(3) as facially
vague fails for all of the reasons we have discussed, and
because he asserts no as-applied challenge to the statute, we
reject his contention that the statute is inconsistent with his due
process rights.
B. Second Amendment
    Cook agrees that Yancey forecloses this challenge to section
922(g)(3). Yancey, as noted, held that there was a substantial
relationship between the government’s legitimate interest in
preventing violent crime and the statute’s ban on gun posses-
sion by unlawful drug users. 621 F.3d at 683–87. Although
Cook asserts that Yancey was wrongly decided, he offers us no
real reason to reconsider our precedent on this point. As the
No. 18-1343                                                   19

law is settled in this circuit, we reject his Second Amendment
objection to the statute.
C. Jury Instruction
    Cook argues finally that the district court did not properly
instruct the jury as to the elements of his offense. As we noted
in our summary of the proceedings below, the court advised
the jury that “[t]he defendant was an unlawful user of mari-
juana if he used marijuana on a regular and ongoing basis for
a period of time that began before and continued through the
date of the offense.” R. 44 at 8; R. 56 at 70–71 (emphasis
omitted). The court added that Cook need not have been under
the influence of marijuana when he possessed a firearm, nor
was the government required to prove that he used marijuana
on any particular date or within a specified number of days of
the offense. (Recall that Cook had rejected the government’s
offer to add language that use of marijuana on a single occasion
was insufficient to establish unlawful drug use.) Cook contends
that the instruction as given was erroneous because (a) it was
not grounded in the language of section 922(g)(3); (b) it was
not consistent with Yancey’s holding as to who constitutes an
unlawful drug user; (c) the instruction was internally inconsis-
tent; and (d) it foreclosed the defense from urging the jurors to
use their own understanding of “unlawful user” in assessing
Cook’s conduct. None of these arguments is persuasive.
    The instruction was grounded in the language of the statute
in that it endeavored, consistent with the case law regarding
section 922(g)(3), to define for the jury who constitutes an
unlawful drug user. The statute itself does not define “unlawful
user.” As discussed, this court in Yancey concluded that an
20                                                   No. 18-1343

unlawful drug user is one who regularly uses a controlled
substance, other than as prescribed by a physician, contempo-
raneously with possessing a firearm. 621 F.3d at 682, 687. In
doing so, we acted in accord with other circuits which have
concluded that the statute’s reach is limited by two key
requirements: (1) regularity of drug use (2) that is sufficiently
contemporaneous with the possession of a firearm. See id.
(collecting cases). That these are limits imposed on the offense
by the judiciary rather than the face of the statute does not
render them invalid. See United States v. Lanier, 520 U.S. 259,
266, 117 S. Ct. 1219, 1225 (1997) (“clarity at the requisite level
may be supplied by judicial gloss on an otherwise uncertain
statute”) (collecting cases); Skilling, supra, 561 U.S. at 405–06,
130 S. Ct. at 2929–30 (before striking down a federal statute as
vague courts will first consider if it is subject to a limiting
construction that avoids vagueness); id. at 409 n.43, 130 S. Ct.
at 2931 n.43 (“cases ‘paring down’ federal statutes to avoid
constitutional shoals are legion”). The district court appropri-
ately looked to Yancey’s gloss on the statute in defining
“unlawful user” for the jury.
    Nor was the instruction inconsistent with Yancey. Cook
suggests that Yancey defined “unlawful user” of drugs to mean
either one who is addicted to controlled substances or one who
has simply used them within the past year, and that the
reference to “regular and ongoing” drug use in the district
court’s instruction is both broader than addiction and narrower
than use within the past year. But Cook’s reading of Yancey is
not a faithful account of the court’s opinion. The opinion makes
clear that section 922(g)(3) requires regular or habitual drug use,
621 F.3d at 682, that is contemporaneous with the possession
No. 18-1343                                                   21

of a firearm, id. at 687. Nowhere in our decision did we suggest
that a single or occasional, irregular use of a controlled sub-
stance within a year of the gun possession was sufficient to
meet these criteria. Nor did we indicate that regular or habitual
use necessarily equates with addiction. The instruction given
here was fully consistent with Yancey’s requirements: the term
“regular” connotes a pattern of repeated drug use (be it
volitional or as the result of an addiction), and “ongoing”
connotes the requisite temporal nexus with possession of the
gun.
    The instruction was also internally consistent. Cook’s
contention to the contrary focuses on the fact that the instruc-
tion advised the jury, on the one hand, that his marijuana use
must have “beg[u]n before and continued through the date of
the charged offense” but, on the other hand, that he need not
have “used marijuana on any particular day, or within a certain
number of days of when he committed the charged offense.” R.
44 at 8; R. 56 at 71. These portions of the instruction were not
at odds with one another. Consistent with Yancey’s require-
ment that the defendant’s drug use be contemporaneous with
his possession of a firearm, the court appropriately advised the
jury that Cook’s marijuana use must have been “ongoing” at
the time he was discovered in possession of a gun. But the
requirement that the drug use and firearm possession be
contemporaneous does not literally mean that the defendant
must have been ingesting (or under the influence of) a con-
trolled substance at the same time as he possessed the gun. The
statute, after all, prohibits firearm possession by a drug user,
not simply possession during drug use. So long as the defen-
dant was still engaged in the regular use of a drug at the time
22                                                   No. 18-1343

of his firearm possession, it is not necessary to show that he
used the drug on the day of his firearm possession, the day
before, or within any particular number of days of the posses-
sion. Thus, a person who routinely uses marijuana on week-
ends may violate section 922(g)(3) by possessing a firearm on
a Tuesday or Wednesday, because his possession of the gun is
contemporaneous with his ongoing pattern of drug use. The
instruction appropriately and coherently advised the jury on
these points.
   Finally, we are no more persuaded than the district judge
was that the instruction should have left it to the jurors to
consult their own collective sense of who constitutes an
“unlawful user” of marijuana. Yancey establishes the relevant
parameters on this point, and the district court was required to
convey those parameters to the jury to guide its decision-
making, which Judge Peterson did admirably.
    That said, our holding should not be construed to foreclose
alternate versions of the “unlawful user” instruction. The Sixth
and Eighth Circuits, for example, have promulgated instruc-
tions with slightly different language. See MANUAL OF MODEL
CRIMINAL JURY INSTRUCTIONS FOR THE DISTRICT COURTS OF THE
EIGHTH CIRCUIT § 6.18.922B, at 291–94 (2017 ed.); United States
v. Burchard, 580 F.3d 341, 352 (6th Cir. 2009). Although the
arguments in this court and in the court below reflect some
anticipation that we might settle upon our own preferred
version of the instruction in this appeal, we respectfully decline
to do so. As the foregoing discussion makes clear, we find no
fault with the particular instruction that Judge Peterson gave to
the jury, and we need not go farther than that to resolve Cook’s
appeal. The task of drafting a model instruction, we believe, is
No. 18-1343                                                      23

better left to our Circuit’s Pattern Criminal Jury Instruction
Committee, which has a membership that includes practitio-
ners and academics as well as judges and which can solicit and
incorporate comments on any proposed instruction from the
bar at large. We have invited the Committee to consider a
pattern instruction for a section 922(g)(3) charge, including but
not limited to the issue of who constitutes an “unlawful user”
of a controlled substance for purposes of this statute.
                               III.
   In compliance with the Supreme Court’s mandate, we must
now consider whether the Court’s decision in Rehaif entitles
Cook to a new trial. At our request, the parties have filed
supplemental briefs on this question, which we have found to
be quite helpful.
     As we noted, Rehaif held that a charge under sections 922(g)
and 924(a)(2) requires proof that a defendant knew that he
possessed the status which rendered it unlawful for him to
possess a firearm. 139 S. Ct. at 2194, 2200. “This decision upset
not only the law of this circuit but the unanimous conclusion of
all the courts of appeals.” United States v. Payne, 964 F.3d 652,
655 (7th Cir. 2020) (citing United States v. Williams, 946 F.3d 968,
970 (7th Cir. 2020)). Post-Rehaif, we have clarified that the
government need not show that the defendant knew his status
prohibited him from possessing a firearm, but simply that he
held the status. United States v. Maez, 960 F.3d 949, 954–55 (7th
Cir. 2020); see also United States v. Triggs, 963 F.3d 710, 714–15
(7th Cir. 2020). So in this case, Cook’s knowledge that he was
an unlawful user of a controlled substance was an element of
the offense.
24                                                    No. 18-1343

    The issue resolved in Rehaif was not one that Cook had
pursued in the district court or in his appeal to this court, but
rather was raised for the first time in Cook’s certiorari petition;
the parties therefore agree it is subject to plain error review.
Fed. R. Crim. P. 52(b); see, e.g., Triggs, 963 F.3d at 712. In order
to establish plain error rendering him eligible for relief, Cook
bears the burden of showing: (1) an error that was not affirma-
tively waived (2) that, in retrospect, is clear or obvious, and (3)
which affected his substantial rights. Molina-Martinez v. United
States, 136 S. Ct. 1338, 1343 (2016); United States v. Marcus, 560
U.S. 258, 262, 130 S. Ct. 2159, 2164 (2010); United States v. Olano,
507 U.S. 725, 732–35, 113 S. Ct. 1770, 1776–78 (1993). Further-
more, relief under Rule 52(b) is discretionary, and should be
granted only when the error seriously affects the fairness,
integrity, or public reputation of judicial proceedings. Olano,
507 U.S. at 732, 735–37, 113 S. Ct. at 1776, 1778–79; see also
Molina-Martinez, 136 S. Ct. at 1343; Rosales-Mireles v. United
States, 138 S. Ct. 1897, 1906–07 (2018); Marcus, 560 U.S. at 262,
130 S. Ct. at 2164.
    Consistent with this circuit’s pre-Rehaif cases, the supersed-
ing indictment omitted any allegation that Cook knew he was
an unlawful user of marijuana, and the jury that convicted
Cook was not instructed that the government was required to
prove Cook’s knowledge in this regard. See, e.g., United States
v. Lane, 267 F.3d 715, 720 (7th Cir. 2001) (sole scienter require-
ment imposed by section 924(a)(1) is that defendant’s posses-
sion of firearm was knowing). As a consequence of these
omissions, the government was relieved of the burden to
establish what Rehaif makes clear is an essential element of the
offense.
No. 18-1343                                                              25

    The parties agree that, in view of Rehaif, it was error for the
jury not to be advised that in order to convict Cook it must find
that he knew he was an unlawful user of marijuana.7 The
parties also agree that, in retrospect, the error is obvious.
Where they part ways is on whether the error implicated
Cook’s substantial rights. An error affects a defendant’s
substantial rights when there is a reasonable probability that,
had the error not occurred, the outcome of the proceeding
would have been different. Molina-Martinez, 136 S. Ct. at 1343;
United States v. Dominguez Benitez, 542 U.S. 74, 76, 81–82, 124 S.
Ct. 2333, 2336, 2339 (2004); Olano, 507 U.S. at 734–35, 113 S. Ct.
at 1777–78; see also United States v. Carson, 870 F.3d 584, 602 (7th
Cir. 2017) (even instructional errors of constitutional dimension
are subject to review for prejudice) (citing United States v.
Cardena, 842 F.3d 959, 998 (7th Cir. 2016)). This is the essentially
same standard that courts employ to assess whether the
ineffective assistance of counsel has prejudiced a defendant, see
Strickland v. Washington, 466 U.S. 668, 694, 104 S. Ct. 2052, 2068
(1984), and to determine whether favorable evidence that the
government has withheld from the defense in violation of
Brady v. Maryland, 373 U.S. 83, 83 S. Ct. 1184 (1963), was
material to the defendant’s guilt or punishment, see Cone v. Bell,
556 U.S. 449, 469–70, 129 S. Ct. 1769, 1783 (2009) (quoting Kyles
v. Whitley, 514 U.S. 419, 435, 115 S. Ct. 1555, 1566 (1995)).
Dominguez Benitez, 542 U.S. at 81–82, 124 S. Ct. at 2339.



7
  We shall hereafter treat the omissions in the indictment and the jury
instructions as a single error comprising a failure to inform the jury of an
essential element of the offense.
26                                                    No. 18-1343

    In order to meet this standard, Cook does not have to show
that it is more likely than not that he would have been acquit-
ted but for the error. Dominguez Benitez, 542 U.S. at 83 n.9, 124
S. Ct. at 2340 n.9; Triggs, 963 F.3d at 717 (citing Williams, 946
F.3d at 973). He need only convince the court that there is a
reasonable probability that the result of the trial might have
been different—that is, one sufficient to undermine confidence
in the actual outcome of the trial, see Strickland, 466 U.S. at 694,
104 S. Ct. at 2068; Cone, 556 U.S. at 470, 129 S. Ct. at 1783, or
put another way, a plausible, non-negligible chance of a more
favorable result, see Sanchez v. Sessions, 894 F.3d 858, 863 (7th
Cir. 2018). See also Myers v. Neal, — F.3d —, 2020 WL 4462619,
at *9 (7th Cir. Aug. 4, 2020) (likelihood of a different result
“must be substantial”) (quoting Harrington v. Richter, 562 U.S.
86, 111-12, 131 S. Ct. 770, 792 (2011)). As the government
agrees, a more favorable outcome includes a deadlocked jury
as well as an acquittal, as neither is a conviction. Gov. Remand
Br. 13–14; see United States v. Nicolaou, 180 F.3d 565, 570 (4th
Cir. 1999) (citing United States v. Hastings, 134 F.3d 235, 240 (4th
Cir. 1998)).
    The error in this case relieved the government of the burden
of proving an essential element of offense beyond a reasonable
doubt. The error was not so fundamental that it qualifies as
structural. Maez, 960 F.3d at 957–58. Nonetheless, it was a
serious error, in the sense that it both omitted a key element of
the government’s case and deprived Cook of the right to have
the jury assess the sufficiency of that evidence as to that
element. See United States v. Holmes, 93 F.3d 289, 294 (7th Cir.
1996); United States v. Perez, 43 F.3d 1131, 1139 (7th Cir. 1994);
United States v. Kerley, 838 F.2d 932, 937–39 (7th Cir. 1988).
No. 18-1343                                                   27

    We have previously said that although the “failure to
instruct clearly on the elements of the offense is not always
plain error … the gravity of such an error makes reversal the
usual outcome in such circumstances.” Perez, 43 F.3d at 1139
(citing Kerley, 838 F.2d at 938–39); see also United States v.
Wheeler, 540 F.3d 683, 690 (7th Cir. 2008); Holmes, 93 F.3d at
294; United States v. Shetterly, 971 F.2d 67, 73 (7th Cir. 1992).
Only in the exceptional case will prejudice not be found. Perez,
43 F.3d at 1139 (citing Kerley, 838 F.2d at 939). The exceptional
case includes one in which the jury necessarily found facts that
were the functional equivalent of the omitted element of the
offense, see United States v. Parmelee, 42 F.3d 387, 393–95 (7th
Cir. 1994), or where the evidence was so strong or the defense
so implausible as to leave no doubt that the jury would have
convicted the defendant if properly advised as to the essential
element, see Kerley, 838 F.3d at 939 (although jury instruction
failed to make clear that knowledge of duty to register for draft
was essential element of failure-to-register offense, error was
not so egregious as to require retrial “where the issue of guilty
knowledge was not contestable and was barely if at all con-
tested”); Williams, 946 F.3d at 974 (collecting section 922(g)(1)
felon-in-possession decisions finding no reasonable probability
of a different result post-Rehaif, where defendants had served
substantial prison terms for prior felony convictions and thus
could not plausibly contend they did not know they held status
of felons at time they possessed firearms).
   Given the nature of the element omitted from the indict-
ment and the jury instructions, we do not think this qualifies as
an exceptional case. The government was required to prove
that Cook had knowledge of a status that has both legal and
28                                                    No. 18-1343

factual elements and is not binary in the way that one’s status
as a convicted felon is, for example. See Triggs, 963 F.3d at
715–16 (distinguishing “the straightforward definition” of felon
who is barred from possessing firearm by section 922(g)(1)
from the “comparative complexity” of the definition of
“misdemeanor crime of domestic violence” found in section
922(g)(9)). One can have used marijuana without necessarily
being an “unlawful user” who is prohibited from possessing a
firearm. This makes the probability stronger that the jury might
not have convicted Cook. Indeed, the fact that the jury was
unable to reach a verdict on the false statement count, which
likewise required proof that Cook knew he was an unlawful
user, makes plain that Cook’s conviction on the section
922(g)(3) charge was not inevitable.
     Knowledge of one’s status under section 922(g)(3) encom-
passes questions of law: Cook had to know both that he was
using a controlled substance and that his use was “unlawful”.
United States v. Bowens, 938 F.3d 790, 797–98 (6th Cir. 2019),
cert. denied, 140 S. Ct. 814, 2572 (2020); see Rehaif, 139 S. Ct. at
2198 (“The defendant’s status as an alien ‘illegally or unlaw-
fully present in the United States’ [see § 922(g)(5)(A)] refers to
a legal matter, but this legal matter is what the commentators
refer to as a ‘collateral’ question of law.”). Knowledge that a
substance is controlled is the more straightforward of these
two propositions, but even that may be tricky in a State like
Illinois, where use of marijuana is now legal as a matter of state
but not federal law. Compare 410 Ill. Comp. Stat. Ann. 705/1-7
with 21 U.S.C. §§ 812 (c)(10) (designating marijuana a Schedule
I controlled substance) and 844 (generally proscribing simple
possession of controlled substances). But Cook was arrested in
No. 18-1343                                                      29

Wisconsin, where state law prohibits marijuana possession and
use, see Wis. Stat. §§ 961.14(4)(t), 961.41(3g)(e); United States v.
Paige, 870 F.3d 693, 700 & n.19 (7th Cir. 2017); and the parties
appear to assume for present purposes that so long as Cook
had knowledge that marijuana use was proscribed in a general
sense, this would be enough to show that he knew he was
using a controlled substance. See Cook Remand Br. 24 (“Cook
is not claiming that in order to meet its Rehaif burden, the
government would have to present affirmative evidence that
Cook understood the statutory phrase ‘unlawful user’ or was
familiar with the Controlled Substances Act.”) (emphasis in
original).
    Knowledge that one is an unlawful user turns on his
awareness of somewhat nuanced factual aspects of his drug
use. As our analysis with respect to the “unlawful user” jury
instruction demonstrates, unlawful use of a drug entails (1) use
other than as lawfully prescribed by a physician, but also
(2) use that was both regular and ongoing at the time that the
defendant possessed a gun. So Cook would have to realize that
he was using marijuana other than as prescribed by a physician,
and that his use was sufficiently regular and ongoing at the
time he possessed the firearm as to make it “unlawful” in the
sense that this and other cases explain (as there is no statutory
standard).
    As we consider what the record tells us about Cook’s
knowledge in these respects, our focus at the third step of the
plain error inquiry—whether the error affected Cook’s substan-
tial rights (i.e., prejudice)—must be confined to the jury record
alone. Maez, 960 F.3d at 959–63. Evidence that lies outside of
30                                                        No. 18-1343

that record (e.g., evidence in the defendant’s pre-sentence
report) comes into play only at the fourth prong of the inquiry,
wherein the court exercises its discretion to correct plain errors
that seriously affect the fairness, integrity, or public reputation
of judicial proceedings. Id. at 962 (quoting Olano, 507 U.S. at
736, 113 S. Ct. at 1779).
    There certainly is evidence in the trial record that would
have supported a jury finding that Cook knew he was an
unlawful user of a controlled substance. He obviously knew
what the scope of his own marijuana use was: he told an
investigator he had been using marijuana for nearly ten years
to “mellow[ ] [himself] out” (R. 22-1 at 3), and he acknowl-
edged that he had smoked two blunts on the day of his arrest.
And the officers who pulled him over could smell marijuana,
confirming that his use was recent. So a properly instructed
jury certainly could have found that his use was both regular
and ongoing as of the date of his arrest. Given the evidence
presented at trial, the jury also might fairly have inferred that
Cook knew marijuana was a controlled substance that was
illegal for him to possess and use. As we have noted, marijuana
possession and use was (and is) prohibited under Wisconsin as
well as federal law. There was no indication that Cook had ever
been prescribed marijuana for medicinal purposes—and,
indeed, Wisconsin does not permit medical marijuana use, see
Paige, 870 F.3d at 700 n.19.8 Moreover, as the government


8
   Cook had also signed an ATF Form 4473 in connection with his
purchase of the gun which reminded him that regardless of any contrary
provision of state law, marijuana use was proscribed by federal law (Gov.
                                                           (continued...)
No. 18-1343                                                           31

points out, Cook had stashed a half-ounce quantity of mari-
juana in his groin area, a fact which could be construed to
suggest that he was hiding the marijuana from authorities
because he knew his possession to be illegal.
    But the evidence was by no means overwhelming on these
points, and Cook’s briefs on remand have convinced us that he
did have a plausible defense to make as to his knowledge. Even
if we take it as a given that Cook understood marijuana was a
controlled substance that was illegal for him to possess and
use, we do not regard it as inevitable that the jury would have
found that Cook knew he was an unlawful user as the case law
defines that term. Particularly in view of the regularity and
contemporaneity components of unlawful use, it is possible for
any given user to think that his use falls outside the range of
regular, ongoing use. Past, regular use would not qualify as
ongoing use if it has come to a definitive end before one
possesses a gun, for example, and likewise current but isolated
use (perhaps only when offered at the occasional social
gathering) likewise would not count as regular use. Cook, of
course, had confessed to a long-term pattern of use that
included the day of his arrest, and he has not suggested that his
use was sporadic. But his counsel points out that Cook detailed
that history of use after the interviewing police officer noted
that “shake” (loose marijuana), packaging, and scales had been
found in Cook’s car during prior traffic stops—all of which


8
  (...continued)
Trial Ex. No. 1), although the government does not place much weight on
this piece of evidence in its plain error analysis. See Government Remand
Br. 10.
32                                                    No. 18-1343

were consistent with distribution of marijuana—and asked him
in a leading manner, “[S]o it’s clear you use, right? You just use.
Is that what you’re saying?” R. 22-1 at 2. Cook might have
surmised that confessing to substantial use of marijuana was
the prudent thing for him to do, as distribution might well have
exposed him to more severe criminal penalties. But even if we
assume that Cook did not exaggerate the extent of his own use,
his perception of whether that use qualified as unlawful was
necessarily subjective. That Cook ought to have known his use
was unlawful would not suffice to convict him; he had to
actually know his use was unlawful. See Rehaif, 139 S. Ct. at 2208
(Alito, J., dissenting); United States v. Balde, 943 F.3d 73, 90 (2d
Cir. 2019).
    Interestingly, the jury was asked to evaluate Cook’s
knowledge in relation to the false statement charge stemming
from the ATF Form 4473 he completed in connection with the
purchase of his gun. As to that charge, the government was
required to show that Cook had falsely certified that he was
not an unlawful user of marijuana and that he knew his
certification was false when he made it, see United States v.
Petitjean, 883 F.2d 1341, 1346 (7th Cir. 1989); and the jury was
instructed accordingly. R. 44 at 5; R. 56 at 67. Cook’s counsel
argued to the jury that the ATF form was unclear and that his
client could only have guessed at whether he qualified as an
unlawful user for purposes of the certification. R. 56 at 82–83.
Although we have no window into the jury’s deliberations, it
is possible that some number of the jurors may have agreed
with that argument, given the deadlock on this count. Given
that the jury would be presented with a quite similar question,
post-Rehaif, on the possession charge, it is not implausible to
No. 18-1343                                                       33

think that a jury properly instructed as to the requirement that
Cook must have known he was an unlawful user of marijuana,
might have also deadlocked on the possession count.
    On balance, we are convinced that the omission in the
indictment and the instructions did affect Cook’s substantial
rights. The question is not whether we find Cook’s potential
defense to the knowledge element persuasive, see Maez, 960
F.3d at 961, but whether there is a reasonable probability that
one or more jurors might have done so. We conclude that the
answer to that question is yes.
    Which brings us to the fourth step of the plain-error inquiry:
whether we should exercise our discretion to grant Cook a new
trial. Additional evidence found in the pre-sentence report
bears on that inquiry; as with the trial record, that evidence
points in different directions. First, prior to his arrest in this
case, Cook had been cited and adjudged liable on three
occasions for marijuana possession in violation of local ordi-
nances (R. 70 ¶¶ 47, 53, 59), and he had also been convicted of
disorderly conduct in 2014 that involved hiding marijuana in
his groin area just as he did in this case (R. 70 ¶ 57), all of which
tends to confirm his awareness that marijuana is a controlled
substance and could be understood as confirmation of his
ongoing use of marijuana at the time of those incidents. But,
second, Cook suffers from learning disabilities and cognitive
deficits (R. 70 ¶¶ 94–96) and has, by his own account, received
Social Security disability benefits since he was a child, (R. 70 ¶
93). A mental status evaluation conducted in 2012, when Cook
was 18, suggested that his cognitive functioning was in the
borderline to sub-average range. A measure of his IQ using the
Wechlser Adult Intelligence Scale-Fourth Edition produced a
34                                                   No. 18-1343

Full Scale IQ of 63, which would put him in the “extremely
low” classification (although previous testing had put him in a
borderline classification, and the 2012 evaluation itself indi-
cated that the result should be viewed with caution given
Cook’s difficulties with attention, focus, and pace during
testing). R. 70 ¶¶ 94, 96. He never completed high school nor
did he earn a G.E.D. R. 70 ¶¶ 104, 106. Arguably, Cook’s
limited education and cognitive deficits might have made it
more difficult for him to appreciate whether his pattern of
marijuana usage rendered him an “unlawful user.” Cf. Triggs,
963 F.3d at 715–16 (noting that relative complexity of section
922(g)(9)’s ban on possession of a firearm by one previously
convicted of a misdemeanor crime of domestic violence made
defendant’s contention that he did not know he held prohibited
status more plausible)
    The government’s case against Cook was certainly solid,
and, again, we view it as quite possible that a properly in-
structed jury would have convicted him. But taking into
account the totality of the evidence, including evidence beyond
the trial record, we are not convinced that Cook’s conviction
was inevitable. Especially in view of the fact that the jury
deadlocked on the false statement count which, like the
possession count (in view of Rehaif) requires that Cook knew he
was an unlawful user of marijuana, the possibility that the jury
might have either deadlocked or acquitted on the possession
count still strikes us as a reasonable one. We can only conclude
that the Rehaif error is one that does affect the fairness, integ-
rity, and public reputation of the proceeding; and we therefore
exercise our discretion in favor of granting Cook relief in the
form of a new trial.
No. 18-1343                                                  35

                              IV.
   We once again reject Cook’s contentions that the term
“unlawful user” found in section 922(g)(3) is unconstitutionally
vague, that the statute’s ban on the possession of a firearm by
an unlawful user of a controlled substance impermissibly
burdens his Second Amendment rights, and that the trial court
did not properly instruct the jury on who constitutes an
“unlawful user” of a controlled substance.
    However, in view of the Supreme Court’s intervening
decision in Rehaif, and what we find to be a reasonable proba-
bility that the outcome of the trial might have been different
had the government been required to prove, and had the jury
been required to find, that Cook knew he was an unlawful user
of marijuana, we reverse the conviction and remand for a new
trial. Circuit Rule 36 shall not apply on remand.
   We once again commend everyone involved in the briefing
and arguing of this case, along with Judge Peterson and
Magistrate Judge Crocker for their thorough and careful
handling of the case below. Their dedication and hard work
have greatly aided this court’s deliberation and resolution of
the appeal. The new trial we have ordered is due solely to the
Supreme Court’s intervening decision in Rehaif and certainly
not owing to any omission on their part.
          REVERSED AND REMANDED FOR NEW TRIAL
