Xiulu Ruan v. United States

(Slip Opinion)              OCTOBER TERM, 2021                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                 XIULU RUAN v. UNITED STATES

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                THE ELEVENTH CIRCUIT

     No. 20–1410. Argued March 1, 2022—Decided June 27, 2022*
Petitioners Xiulu Ruan and Shakeel Kahn are medical doctors licensed
  to prescribe controlled substances. Each was tried for violating 21
  U. S. C. §841, which makes it a federal crime, “[e]xcept as authorized[,]
  . . . for any person knowingly or intentionally . . . to manufacture, dis-
  tribute, or dispense . . . a controlled substance.” A federal regulation
  authorizes registered doctors to dispense controlled substances via
  prescription, but only if the prescription is “issued for a legitimate
  medical purpose by an individual practitioner acting in the usual
  course of his professional practice.” 21 CFR §1306.04(a). At issue in
  Ruan’s and Kahn’s trials was the mens rea required to convict under
  §841 for distributing controlled substances not “as authorized.” Ruan
  and Kahn each contested the jury instructions pertaining to mens rea
  given at their trials, and each was ultimately convicted under §841 for
  prescribing in an unauthorized manner. Their convictions were sepa-
  rately affirmed by the Courts of Appeals.
Held: Section 841’s “knowingly or intentionally” mens rea applies to the
  statute’s “except as authorized” clause. Once a defendant meets the
  burden of producing evidence that his or her conduct was “authorized,”
  the Government must prove beyond a reasonable doubt that the de-
  fendant knowingly or intentionally acted in an unauthorized manner.
  Pp. 4–16.
     (a) Criminal law generally seeks to punish conscious wrongdoing.
  Thus, when interpreting criminal statutes, the Court “start[s] from a
  longstanding presumption . . . that Congress intends to require a de-
  fendant to possess a culpable mental state.” Rehaif v. United States,
——————
  * Together with No. 21–5261, Kahn v. United States, on certiorari to
the United States Court of Appeals for the Tenth Circuit.
2                   XIULU RUAN v. UNITED STATES

                                  Syllabus

    588 U. S. ___, ___. This culpable mental state, known as scienter, re-
    fers to the degree of knowledge necessary to make a person criminally
    responsible for his or her acts. See ibid. The presumption of scienter
    applies even when a statute does not include a scienter provision, and
    when a statute does “includ[e] a general scienter provision,” “the pre-
    sumption applies with equal or greater force” to the scope of that pro-
    vision. Ibid. The Court has accordingly held that a word such as
    “knowingly” modifies not only the words directly following it, but also
    those other statutory terms that “separate wrongful from innocent
    acts.” Id., at ___.
       Here, §841 contains a general scienter provision—“knowingly or in-
    tentionally.” And in §841 prosecutions, authorization plays a “crucial”
    role in separating innocent conduct from wrongful conduct. United
    States v. X-Citement Video, Inc., 513 U. S. 64, 73. Moreover, the regu-
    latory language defining an authorized prescription is “ambiguous”
    and “open to varying constructions,” Gonzales v. Oregon, 546 U. S. 243,
    258, meaning that prohibited conduct (issuing invalid prescriptions) is
    “often difficult to distinguish” from acceptable conduct (issuing valid
    prescriptions). United States v. United States Gypsum Co., 438 U. S.
    422, 441. A strong scienter requirement helps reduce the risk of “over-
    deterrence,” i.e., punishing conduct that lies close to, but on the per-
    missible side of, the criminal line. Ibid.
       The statutory provisions at issue here are also not the kind to which
    the Court has held the presumption of scienter does not apply. Section
    841 does not define a regulatory or public welfare offense that carries
    only minor penalties. Cf. Rehaif, 588 U. S., at ___; Staples v. United
    States, 511 U. S. 600, 618–619. Nor is the “except as authorized”
    clause a jurisdictional provision. Cf. Rehaif, 588 U. S., at ___. Pp. 5–
    8.
       (b) Analogous precedent reinforces the Court’s conclusion here. In
    Liparota v. United States, 471 U. S. 419, United States v. X-Citement
    Video, 513 U. S. 64, and Rehaif v. United States, 588 U. S. ___, the
    Court interpreted statutes containing a general scienter provision
    (“knowingly”), and considered what mental state applied to a statutory
    clause that did not immediately follow the “knowingly” provision. In
    all three cases, the Court held that “knowingly” modified the statutory
    clause in question because that clause played a critical role in separat-
    ing a defendant’s wrongful from innocent conduct. See Liparota, 471
    U. S., at 426; X-Citement Video, 513 U. S., at 72–73; Rehaif, 588 U. S.,
    at ___. As in those cases, the Court today concludes that §841’s mens
    rea applies to the “[e]xcept as authorized” clause, which serves to sep-
    arate a defendant’s wrongful from proper conduct.                Pp. 8–9.
       (c) Neither the Government’s nor the concurrence’s contrary argu-
                   Cite as: 597 U. S. ____ (2022)                      3

                              Syllabus

ments are convincing. First, the Government and the concurrence cor-
rectly note that the statutory clauses in the cases just described set
forth elements of an offense. Here, the Government and the concur-
rence say, §841’s “[e]xcept as authorized” clause does not set forth an
element of the offense. In support, they point to a separate statutory
provision—§885. Section 885 says that the Government need not “neg-
ative any exemption or exception . . . in any complaint, information,
indictment, or other pleading or in any trial,” and that “the burden of
going forward with the evidence with respect to any such exemption or
exception shall be upon the person claiming its benefit,” not upon the
prosecution. But even assuming that lack of authorization is unlike
an element in these two ways, §885 has little or nothing to do with
scienter requirements. Section 885 simply absolves the Government
of having to allege, in an indictment, the inapplicability of every stat-
utory exception in each Controlled Substances Act prosecution. Sec-
tion 885 also shifts the burden of production—but not the burden of
persuasion—regarding statutory exceptions to the defendant, thereby
relieving the Government of having to disprove, at the outset of every
prosecution, the inapplicability of all exceptions.
   Section 885 thus does not provide a basis for inferring that Congress
intended to do away with, or weaken, ordinary and longstanding sci-
enter requirements. At the same time, the factors discussed above—
the language of §841; the crucial role authorization plays in distin-
guishing morally blameworthy conduct from socially necessary con-
duct; the serious nature of the crime and its penalties; and the vague,
highly general regulatory language defining the scope of prescribing
authority—all support applying normal scienter principles to the “ex-
cept as authorized” clause. And the Government does not deny that,
once a defendant satisfies his burden of production under §885 by in-
voking the authorization exception, the Government must then prove
lack of authorization by satisfying the ordinary criminal law burden of
proof—beyond a reasonable doubt.
   The Government also offers a substitute mens rea standard. Instead
of applying the statute’s “knowingly or intentionally” language to the
authorization clause, the Government instead asserts that the statute
implicitly contains an “objectively reasonable good-faith effort” or “ob-
jective honest-effort standard.” Brief for United States 16–17. But
§841 uses the words “knowingly or intentionally,” not “good faith,” “ob-
jectively,” “reasonable,” or “honest effort.” And the Government’s
standard would turn a defendant’s criminal liability on the mental
state of a hypothetical “reasonable” doctor, rather than on the mental
state of the defendant himself or herself. The Court has rejected anal-
ogous suggestions in other criminal contexts. See Elonis v. United
States, 575 U. S. 723. And the Government is wrong to assert that the
4                   XIULU RUAN v. UNITED STATES

                                   Syllabus

    Court effectively endorsed its honest-effort standard in United States
    v. Moore, 423 U. S. 122, as that case did not address mens rea at all.
    Nor does United States v. Yermian, 468 U. S. 63, support the Govern-
    ment here, as that case dealt with a jurisdictional clause, to which the
    presumption of scienter does not apply.
       Finally, the Government argues that requiring it to prove that a doc-
    tor knowingly or intentionally acted not “as authorized” will allow bad-
    apple doctors to escape liability by claiming idiosyncratic views about
    their prescribing authority. But the Court has often rejected this kind
    of argument, see, e.g., Rehaif, 588 U. S., at ___, and does so again here.
    Pp. 9–15.
       (d) The Court of Appeals in both cases evaluated the jury instruc-
    tions relating to mens rea under an incorrect understanding of §841’s
    scienter requirements. On remand, those courts may address whether
    the instructions complied with the mens rea standard set forth here,
    as well as whether any instructional error was harmless. P. 15.
966 F. 3d 1101 and 989 F. 3d 806, vacated and remanded.

   BREYER, J. delivered the opinion of the Court, in which ROBERTS, C. J.,
and SOTOMAYOR, KAGAN, GORSUCH, and KAVANAUGH, JJ., joined. ALITO,
J., filed an opinion concurring in the judgment, in which THOMAS, J.,
joined, and in which BARRETT, J., joined as to Parts I–A, I–B, and II.
                        Cite as: 597 U. S. ____ (2022)                                 1

                              Opinion of the Court

     NOTICE: This opinion is subject to formal revision before publication in the
     preliminary print of the United States Reports. Readers are requested to
     notify the Reporter of Decisions, Supreme Court of the United States, Wash-
     ington, D. C. 20543, of any typographical or other formal errors, in order that
     corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                    _________________

                          Nos. 20–1410 and 21–5261
                                    _________________


                    XIULU RUAN, PETITIONER
20–1410                       v.
                        UNITED STATES
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
          APPEALS FOR THE ELEVENTH CIRCUIT



                 SHAKEEL KAHN, PETITIONER
21–5261                     v.
                      UNITED STATES
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE TENTH CIRCUIT
                                  [June 27, 2022]

   JUSTICE BREYER delivered the opinion of the Court.
   A provision of the Controlled Substances Act, codified at
21 U. S. C. §841, makes it a federal crime, “[e]xcept as au-
thorized[,] . . . for any person knowingly or intentionally . . .
to manufacture, distribute, or dispense . . . a controlled sub-
stance,” such as opioids. 84 Stat. 1260, 21 U. S. C. §841(a)
(emphasis added). Registered doctors may prescribe these
substances to their patients. But, as provided by regula-
tion, a prescription is only authorized when a doctor issues
it “for a legitimate medical purpose . . . acting in the usual
course of his professional practice.” 21 CFR §1306.04(a)
(2021).
2              XIULU RUAN v. UNITED STATES

                     Opinion of the Court

   In each of these two consolidated cases, a doctor was con-
victed under §841 for dispensing controlled substances not
“as authorized.” The question before us concerns the state
of mind that the Government must prove to convict these
doctors of violating the statute. We hold that the statute’s
“knowingly or intentionally” mens rea applies to authoriza-
tion. After a defendant produces evidence that he or she
was authorized to dispense controlled substances, the Gov-
ernment must prove beyond a reasonable doubt that the de-
fendant knew that he or she was acting in an unauthorized
manner, or intended to do so.
                               I
   The question we face concerns §841’s exception from the
general prohibition on dispensing controlled substances
contained in the phrase “[e]xcept as authorized.” In partic-
ular, the question concerns the defendant’s state of mind.
To prove that a doctor’s dispensation of drugs via prescrip-
tion falls within the statute’s prohibition and outside the
authorization exception, is it sufficient for the Government
to prove that a prescription was in fact not authorized, or
must the Government prove that the doctor knew or in-
tended that the prescription was unauthorized?
   Petitioners Xiulu Ruan and Shakeel Kahn are both doc-
tors who actively practiced medicine. They both possessed
licenses permitting them to prescribe controlled sub-
stances. The Government separately charged them with
unlawfully dispensing and distributing drugs in violation of
§841. Each proceeded to a jury trial, and each was con-
victed of the charges.
   At their separate trials, Ruan and Kahn argued that their
dispensation of drugs was lawful because the drugs were
dispensed pursuant to valid prescriptions. As noted above,
a regulation provides that, “to be effective,” a prescription
“must be issued for a legitimate medical purpose by an in-
                  Cite as: 597 U. S. ____ (2022)             3

                      Opinion of the Court

dividual practitioner acting in the usual course of his pro-
fessional practice.” 21 CFR §1306.04(a). We assume, as did
the courts below and the parties here, that a prescription is
“authorized” and therefore lawful if it satisfies this stand-
ard. At Ruan’s and Kahn’s trials, the Government argued
that the doctors’ prescriptions failed to comply with this
standard. The doctors argued that their prescriptions did
comply, and that, even if not, the doctors did not knowingly
deviate or intentionally deviate from the standard.
   Ruan, for example, asked for a jury instruction that
would have required the Government to prove that he sub-
jectively knew that his prescriptions fell outside the scope of
his prescribing authority. The District Court, however, re-
jected this request. The court instead set forth a more ob-
jective standard, instructing the jury that a doctor acts law-
fully when he prescribes “in good faith as part of his medical
treatment of a patient in accordance with the standard of
medical practice generally recognized and accepted in the
United States.” App. to Pet. for Cert. in No. 20–410, p.
139a. The court further instructed the jury that a doctor
violates §841 when “the doctor’s actions were either not for
a legitimate medical purpose or were outside the usual
course of professional medical practice.” Ibid. The jury con-
victed Ruan, and the trial court sentenced him to over 20
years in prison and ordered him to pay millions of dollars
in restitution and forfeiture.
   The Eleventh Circuit affirmed Ruan’s convictions. See
966 F. 3d 1101, 1120, 1166–1167 (2020). The appeals court
held that a doctor’s “subjectiv[e] belie[f] that he is meeting
a patient’s medical needs by prescribing a controlled sub-
stance” is not a “complete defense” to a §841 prosecution.
Id., at 1167. Rather, the court said, “ ‘[w]hether a defendant
acts in the usual course of his professional practice must be
evaluated based on an objective standard, not a subjective
standard.’ ” Id., at 1166 (quoting United States v. Joseph,
4               XIULU RUAN v. UNITED STATES

                       Opinion of the Court

709 F. 3d 1082, 1097 (CA11 2013); emphasis added; altera-
tion in original).
   Kahn’s trial contained similar disagreements over the
proper mens rea instructions. Ultimately, the District
Court instructed the jury that it should not convict if it
found that Kahn acted in “good faith,” defined as “an at-
tempt to act in accordance with what a reasonable physi-
cian should believe to be proper medical practice.” App.
486. The court added that to find “good faith,” the jury must
conclude that Kahn “acted in an honest effort to prescribe
for patients’ medical conditions in accordance with gener-
ally recognized and accepted standards of practice.” Ibid.
The court also told the jury that “good faith” was a “com-
plete defense” because it “would be inconsistent with know-
ingly and intentionally distributing and/or dispensing con-
trolled substances outside the usual course of professional
practice and without a legitimate medical purpose.” Ibid.
The jury convicted Kahn of the §841 charges, and he was
sentenced to 25 years in prison.
   The Tenth Circuit affirmed Kahn’s convictions. See 989
F. 3d 806, 812, 824–826 (2021). In doing so, the court held
that to convict under §841, the Government must prove
that a doctor “either: (1) subjectively knew a prescription
was issued not for a legitimate medical purpose; or (2) is-
sued a prescription that was objectively not in the usual
course of professional practice.” Id., at 825.
   Both Ruan and Kahn filed petitions for certiorari. We
granted the petitions and consolidated the cases to consider
what mens rea applies to §841’s authorization exception.
                                II
  As we have said, §841 makes it unlawful, “[e]xcept as au-
thorized[,] . . . for any person knowingly or intentionally . . .
to manufacture, distribute, or dispense . . . a controlled sub-
stance.” We now hold that §841’s “knowingly or intention-
ally” mens rea applies to the “except as authorized” clause.
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                      Opinion of the Court

This means that once a defendant meets the burden of pro-
ducing evidence that his or her conduct was “authorized,”
the Government must prove beyond a reasonable doubt
that the defendant knowingly or intentionally acted in an
unauthorized manner. Our conclusion rests upon several
considerations.
                                A
  First, as a general matter, our criminal law seeks to pun-
ish the “ ‘vicious will.’ ” Morissette v. United States, 342
U. S. 246, 251 (1952); see also id., at 250, n. 4 (quoting F.
Sayre, Cases on Criminal Law, p. xxxvi (R. Pound ed.
1927)). With few exceptions, “ ‘wrongdoing must be con-
scious to be criminal.’ ” Elonis v. United States, 575 U. S.
723, 734 (2015) (quoting Morissette, 342 U. S., at 252). In-
deed, we have said that consciousness of wrongdoing is a
principle “as universal and persistent in mature systems of
[criminal] law as belief in freedom of the human will and a
consequent ability and duty of the normal individual to
choose between good and evil.” Id., at 250.
  Consequently, when we interpret criminal statutes, we
normally “start from a longstanding presumption, traceable
to the common law, that Congress intends to require a de-
fendant to possess a culpable mental state.” Rehaif v.
United States, 588 U. S. ___, ___ (2019) (slip op., at 3). We
have referred to this culpable mental state as “scienter,”
which means the degree of knowledge necessary to make a
person criminally responsible for his or her acts. See ibid.;
Black’s Law Dictionary 1613 (11th ed. 2019); Morissette,
342 U. S., at 250–252.
  Applying the presumption of scienter, we have read into
criminal statutes that are “silent on the required mental
state”—meaning statutes that contain no mens rea provi-
sion whatsoever—“ ‘that mens rea which is necessary to sep-
arate wrongful conduct from “otherwise innocent con-
duct.” ’ ” Elonis, 575 U. S., at 736 (quoting Carter v. United
6               XIULU RUAN v. UNITED STATES

                      Opinion of the Court

States, 530 U. S. 255, 269 (2000); emphasis added). Unsur-
prisingly, given the meaning of scienter, the mens rea we
have read into such statutes is often that of knowledge or
intent. See, e.g., Staples v. United States, 511 U. S. 600, 619
(1994); United States v. United States Gypsum Co., 438
U. S. 422, 444–446 (1978).
   And when a statute is not silent as to mens rea but in-
stead “includes a general scienter provision,” “the presump-
tion applies with equal or greater force” to the scope of that
provision. Rehaif, 588 U. S., at ___ (slip op., at 3) (emphasis
added). We have accordingly held that a word such as
“knowingly” modifies not only the words directly following
it, but also those other statutory terms that “separate
wrongful from innocent acts.” Id., at ___ (slip op., at 6); see,
e.g., ibid.; United States v. X-Citement Video, Inc., 513 U. S.
64, 72 (1994); Liparota v. United States, 471 U. S. 419, 426
(1985).
   Section 841 contains a general scienter provision—
“knowingly or intentionally.” And in §841 prosecutions, a
lack of authorization is often what separates wrongfulness
from innocence. Defendants who produce evidence that
they are “authorized” to dispense controlled substances are
often doctors dispensing drugs via prescription. We nor-
mally would not view such dispensations as inherently ille-
gitimate; we expect, and indeed usually want, doctors to
prescribe the medications that their patients need. In §841
prosecutions, then, it is the fact that the doctor issued an
unauthorized prescription that renders his or her conduct
wrongful, not the fact of the dispensation itself. In other
words, authorization plays a “crucial” role in separating in-
nocent conduct—and, in the case of doctors, socially benefi-
cial conduct—from wrongful conduct. X-Citement Video,
513 U. S., at 73. Applying §841’s “knowingly or intention-
ally” mens rea to the authorization clause thus “helps ad-
vance the purpose of scienter, for it helps to separate wrong-
ful from innocent acts.” Rehaif, 588 U. S., at ___ (slip op.,
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                      Opinion of the Court

at 6); see also X-Citement Video, 513 U. S., at 72–73.
   In addition, the regulatory language defining an author-
ized prescription is, we have said, “ambiguous,” written in
“generalit[ies], susceptible to more precise definition and
open to varying constructions.” Gonzales v. Oregon, 546
U. S. 243, 258 (2006); see id., at 257 (regulation “gives little
or no instruction on” major questions); see also 21 CFR
§1306.04(a) (regulation defining “effective” prescription as
one “issued for a legitimate medical purpose by an individ-
ual practitioner acting in the usual course of his profes-
sional practice”). The conduct prohibited by such language
(issuing invalid prescriptions) is thus “often difficult to dis-
tinguish from the gray zone of socially acceptable . . . con-
duct” (issuing valid prescriptions). United States Gypsum,
438 U. S., at 441. A strong scienter requirement helps to
diminish the risk of “overdeterrence,” i.e., punishing ac-
ceptable and beneficial conduct that lies close to, but on the
permissible side of, the criminal line. Ibid.
   The statutory provisions at issue here are also not the
kind that we have held fall outside the scope of ordinary
scienter requirements. Section 841 does not define a regu-
latory or public welfare offense that carries only minor pen-
alties. Cf. Rehaif, 588 U. S., at ___ (slip op., at 6); Staples,
511 U. S., at 606. Rather, §841 imposes severe penalties
upon those who violate it, including life imprisonment and
fines up to $1 million. See §841(b)(1)(C); see generally
§841(b). Such severe penalties counsel in favor of a strong
scienter requirement. See Staples, 511 U. S., at 618–619
(noting that “a severe penalty is a further factor tending to
suggest that . . . the usual presumption that a defendant
must know the facts that make his conduct illegal should
apply”); United States Gypsum, 438 U. S., at 442, n. 18.
   Nor is the “except as authorized” clause a jurisdictional
provision, to which the presumption of scienter would not
apply. Cf. Rehaif, 588 U. S., at ___ (slip op., at 4); United
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                      Opinion of the Court

States v. Yermian, 468 U. S. 63, 68–69 (1984). To the con-
trary, and as we have explained, a lack of authorization is
often the critical thing distinguishing wrongful from proper
conduct.
                                B
   Analogous precedent reinforces our conclusion. In Lipa-
rota, we interpreted a statute penalizing anyone who
“ ‘knowingly uses [food stamps] in any manner not author-
ized by’ ” statute. 471 U. S., at 420. We held that “know-
ingly” modified both the “use” of food stamps element and
the element that the use be “not authorized.” Id., at 423,
433. We applied “knowingly” to the authorization language
even though Congress had not “explicitly and unambigu-
ously” indicated that it should so apply. Id., at 426. But if
knowingly did not modify the fact of nonauthorization, we
explained, the statute “would . . . criminalize a broad range
of apparently innocent conduct.” Ibid.
   Similarly, in X-Citement Video, we interpreted a statute
penalizing anyone who “ ‘knowingly transports’ ” or “ ‘know-
ingly receives’ ” videos “ ‘involv[ing] the use of a minor en-
gaging in sexually explicit conduct.’ ” 513 U. S., at 68. We
held that “knowingly” applied not only to the element of
transporting or receiving videos but also to the elemental
fact that the videos involve “the use of a minor.” Id., at 66.
We recognized that this was not “the most grammatical
reading of the statute.” Id., at 70. But, we explained, “the
age of the performers is the crucial element separating legal
innocence from wrongful conduct,” for possessing sexually
explicit videos involving nonminors is protected First
Amendment activity. Id., at 72–73.
   Finally, in Rehaif, we interpreted a statutory scheme in
which one statutory subsection provided penalties for any-
one who “knowingly violates” a separate subsection. 588
U. S., at ___–___ (slip op., at 3–4). This latter subsection
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                      Opinion of the Court

made it “unlawful” for people with certain statuses (i.e., be-
ing a felon or being in the country unlawfully) to possess a
gun. Ibid. We held that the first subsection’s “knowingly”
language applied to the status element in the second sub-
section. Id., at ___ (slip op., at 5). To convict under the
statute, then, the Government had to prove that a defend-
ant knew he had one of the listed statuses. Ibid. “Without
knowledge of that status,” we reasoned, “the defendant may
well lack the intent needed to make his behavior wrongful,”
because “[a]ssuming compliance with ordinary licensing re-
quirements, the possession of a gun can be entirely inno-
cent.” Id., at ___ (slip op., at 6).
   Like the statutes at issue in these cases, the statute here
contains a scienter provision. Section 841 states: “Except
as authorized by this subchapter, it shall be unlawful for
any person knowingly or intentionally . . . to manufacture,
distribute, or dispense . . . a controlled substance.” (Em-
phasis added.) Like those three cases, the question here
concerns the mental state that applies to a statutory clause
(“[e]xcept as authorized”) that does not immediately follow
the scienter provision. Like the three cases, the statutory
clause in question plays a critical role in separating a de-
fendant’s wrongful from innocent conduct. And, like the
Court in those cases, we conclude that the statute’s mens
rea applies to that critical clause.
                             III
   We are not convinced by the Government’s arguments to
the contrary. First, the Government correctly points out,
and the concurrence emphasizes, that the statutory lan-
guage at issue in the cases we have just described set forth
elements of the offense. Here, the Government and the con-
currence say, the “except as authorized” clause does not set
forth an element. See, e.g., post, at 4–7 (ALITO, J., concur-
ring in judgment).
   The Government and the concurrence point to two ways
10             XIULU RUAN v. UNITED STATES

                      Opinion of the Court

in which the “except as authorized” clause is unlike an ele-
ment, both of which rely on a different provision of the Con-
trolled Substances Act—§885. Section 885 says that the
Government need not “negative”—i.e., refute—“any exemp-
tion or exception . . . in any complaint, information, indict-
ment, or other pleading.” This means that, in a prosecution
under the Controlled Substances Act, the Government need
not refer to a lack of authorization (or any other exemption
or exception) in the criminal indictment. Cf. United States
v. Resendiz-Ponce, 549 U. S. 102, 108 (2007) (criminal in-
dictment must set forth all elements of the charged crime).
Section 885 also says that the Government need not “nega-
tive any exemption or exception . . . in any trial,” and that
“the burden of going forward with the evidence with respect
to any such exemption or exception shall be upon the person
claiming its benefit,” not upon the prosecution. Cf. Patter-
son v. New York, 432 U. S. 197, 210 (1977) (Government
bears burden of proving all elements of charged offense).
   But even assuming that lack of authorization is unlike an
element for the two purposes that §885 sets forth, those two
purposes have little or nothing to do with scienter require-
ments. The first has to do with the indictment. It simply
says that the Government need not set forth in an indict-
ment a lack of authorization, or otherwise allege that a de-
fendant does not fall within the many exceptions and ex-
emptions that the Controlled Substances Act contains. The
Act excepts, for example, licensed professionals such as
dentists, veterinarians, scientific investigators, and phar-
macists from the prohibition on dispensing controlled sub-
stances. See 21 U. S. C. §802(21). The Act also excepts em-
ployees of drug manufacturers, common carriers, and
people with sick family members or pets from the prohibi-
tion on possessing controlled substances. See §§802(27),
822(c). Section 885 merely absolves the Government of hav-
ing to allege, in an indictment, the inapplicability of every
                  Cite as: 597 U. S. ____ (2022)            11

                      Opinion of the Court

statutory exception in each Controlled Substances Act pros-
ecution.
   Section 885’s second purpose refers only to “the burden of
going forward with the evidence,” i.e., the burden of produc-
tion. See Black’s Law Dictionary, at 244. It says nothing
regarding the distinct issue of the burden of persuasion—
i.e., the burden of proving a lack of authorization. Cf. Di-
rector, Office of Workers’ Compensation Programs v. Green-
wich Collieries, 512 U. S. 267, 274 (1994) (“our opinions con-
sistently distinguis[h] between burden of proof, which we
defined as burden of persuasion, and . . . the burden of pro-
duction or the burden of going forward with the evidence”);
see also Schaffer v. Weast, 546 U. S. 49, 56 (2005). Section
885 can thus be understood as providing a presumptive de-
vice, akin to others we have recognized in the criminal con-
text, which “merely shift[s] the burden of production to the
defendant, following the satisfaction of which the ultimate
burden of persuasion returns to the prosecution.” County
Court of Ulster Cty. v. Allen, 442 U. S. 140, 157–158, n. 16
(1979); see Parker v. Matthews, 567 U. S. 37, 42, n. 1 (2012)
(per curiam). Contrary to the concurrence’s assertion, see
post, at 9–11, the differences between these two burdens
and the use of procedural mechanisms to shift one burden
but not the other are well established. See, e.g., 29 Am. Jur.
2d Evidence §207, p. 246 (2019) (“due process does not pro-
hibit the use of a . . . procedural device that shifts to a de-
fendant the burden of producing some evidence contesting
a fact that may otherwise be inferred, provided the prose-
cution retains the ultimate burden of proof ”); 1 W. LaFave,
Substantive Criminal Law §1.8(a), p. 102 (3d ed. 2018) (sim-
ilar). In a §841 prosecution, then, once the defendant sat-
isfies the initial burden of production by producing evidence
of authorization, the burden of proving a lack of authoriza-
tion shifts back to the Government. And, as with §885’s
indictment-related purpose, §885’s burden-related purpose
simply relieves the Government from having to disprove, at
12             XIULU RUAN v. UNITED STATES

                      Opinion of the Court

the outset of every Controlled Substances Act prosecution,
every exception in the statutory scheme.
   Section 885 thus does not provide a basis for inferring
that Congress intended to do away with, or weaken, ordi-
nary and longstanding scienter requirements. At the same
time, the language of §841 (which explicitly includes a
“knowingly or intentionally” provision); the crucial role au-
thorization (or lack thereof ) plays in distinguishing morally
blameworthy conduct from socially necessary conduct; the
serious nature of the crime and its penalties; and the vague,
highly general language of the regulation defining the
bounds of prescribing authority all support applying nor-
mal scienter principles to the “except as authorized” clause.
That statutory requirement, while differing from an ele-
ment in some respects, is sufficiently like an element in re-
spect to the matter at issue here as to warrant similar legal
treatment.
   And the Government does not deny that, once a defend-
ant claims that he or she falls within the authorization ex-
ception and the burden shifts back to the Government, the
Government must prove a lack of authorization by satisfy-
ing the ordinary criminal law burden of proof—beyond a
reasonable doubt. See Brief for United States 26; Tr. of
Oral Arg. 50–51; see also id., at 62–65. But see post, at 10–
11 (concurrence suggesting, contrary to the position ad-
vanced by all parties to these cases, that the Government
need only prove lack of authorization by a preponderance of
the evidence). Once the defendant meets his or her burden
of production, then, the Government must prove lack of au-
thorization beyond a reasonable doubt.
   Resisting the “knowingly or intentionally” standard, the
Government instead offers a substitute mens rea standard.
The Government says that rather than simply apply the
statute’s “knowingly or intentionally” language to the au-
thorization clause, we should read the statute as implicitly
containing an “objectively reasonable good-faith effort” or
                  Cite as: 597 U. S. ____ (2022)           13

                      Opinion of the Court

“objective honest-effort standard.” Brief for United States
16–17; cf. post, at 13 (concurrence arguing that doctors can
defend against a §841 prosecution by proving that they
have “act[ed] in subjective good faith in prescribing drugs”).
That is to say, once a defendant meets his or her burden of
production, the Government can convict “by proving beyond
a reasonable doubt that [the defendant] did not even make
an objectively reasonable attempt to ascertain and act
within the bounds of professional medicine.” Brief for
United States 16.
   We are not convinced. For one thing, §841, like many
criminal statutes, uses the familiar mens rea words “know-
ingly or intentionally.” It nowhere uses words such as “good
faith,” “objectively,” “reasonable,” or “honest effort.”
   For another, the Government’s standard would turn a de-
fendant’s criminal liability on the mental state of a hypo-
thetical “reasonable” doctor, not on the mental state of the
defendant himself or herself. Cf. id., at 24 (Government ar-
guing that “a physician can violate Section 841(a) when he
makes no objectively reasonable attempt to conform his
conduct to something that his fellow doctors would view as
medical care” (emphasis added)).
   We have rejected analogous suggestions in other criminal
contexts. In Elonis, for example, we considered the mental
state applicable to a statute that criminalized threatening
communications but contained no explicit mens rea require-
ment. 575 U. S., at 732. The Government argued that the
statute required proof that a reasonable person would find
the communications threatening. Id., at 738–739. But, we
said, “[h]aving liability turn on whether a ‘reasonable per-
son’ regards the communication as a threat—regardless of
what the defendant thinks—reduces culpability on the all-
important element of the crime to negligence.” Id., at 738
(some internal quotation marks omitted). “[A]nd,” we em-
phasized, “we ‘have long been reluctant to infer that a neg-
ligence standard was intended in criminal statutes.’ ” Ibid.
14              XIULU RUAN v. UNITED STATES

                       Opinion of the Court

(quoting Rogers v. United States, 422 U. S. 35, 47 (1975)
(Marshall, J., concurring)). We believe the same of the Gov-
ernment’s proposed standard here.
  The Government asserts that we held to the contrary,
and “effectively endorsed” its honest-effort standard, in
United States v. Moore, 423 U. S. 122 (1975). Brief for
United States 26. But the question in Moore was whether
doctors could ever be held criminally liable under §841. 423
U. S., at 124. Moore did not directly address the issue be-
fore us here regarding the mens rea required to convict un-
der the statute.
  Further, the Government, citing Yermian, notes that the
authorization clause precedes the words “knowingly or in-
tentionally.” And, the Government argues, grammatically
speaking, that fact prevents the latter mens rea provision
from modifying the former clause. See Brief for United
States 24–25. But Yermian based its holding on the fact
that the clause preceding the mens rea provision set forth a
jurisdictional criteria, which is typically not subject to a sci-
enter requirement. 468 U. S., at 68–69; see also Rehaif, 588
U. S., at ___ (slip op., at 4). Yermian did not base its holding
on the grammatical positioning of the statutory language.
  Finally, the Government argues that requiring it to prove
that a doctor knowingly or intentionally acted not as au-
thorized will allow bad-apple doctors to escape liability by
claiming idiosyncratic views about their prescribing au-
thority. See, e.g., Brief for United States 33. This kind of
argument, however, can be made in many cases imposing
scienter requirements, and we have often rejected it on ba-
ses similar to those we have set forth in Part II of this opin-
ion. See, e.g., Rehaif, 588 U. S., at ___ (slip op., at 8); Lipa-
rota, 471 U. S., at 433–434.
  We do the same here. The Government, of course, can
prove knowledge of a lack of authorization through circum-
stantial evidence. See ibid. And the regulation defining the
scope of a doctor’s prescribing authority does so by reference
                  Cite as: 597 U. S. ____ (2022)            15

                      Opinion of the Court

to objective criteria such as “legitimate medical purpose”
and “usual course” of “professional practice.” 21 CFR
§1306.04(a); see Gonzales, 546 U. S., at 285 (Scalia, J., dis-
senting) (“The use of the word ‘legitimate’ connotes an ob-
jective standard of ‘medicine’ ”); Moore, 423 U. S., at 141–
142 (describing Congress’ intent “to confine authorized
medical practice within accepted limits” (emphasis added)).
As we have said before, “the more unreasonable” a defend-
ant’s “asserted beliefs or misunderstandings are,” espe-
cially as measured against objective criteria, “the more
likely the jury . . . will find that the Government has carried
its burden of proving knowledge.” Cheek v. United States,
498 U. S. 192, 203–204 (1991). But the Government must
still carry this burden. And for purposes of a criminal con-
viction under §841, this requires proving that a defendant
knew or intended that his or her conduct was unauthorized.
                             IV
   The Government argues that we should affirm Ruan’s
and Kahn’s convictions because the jury instructions at
their trials conveyed the requisite mens rea. Alternatively,
the Government argues that any instructional error was
harmless. But the Court of Appeals in both cases evaluated
the jury instructions under an incorrect understanding of
§841’s scienter requirements. We decline to decide in the
first instance whether the instructions complied with the
standard we have set forth today. Cf. Rehaif, 588 U. S., at
___ (slip op., at 11). We leave that and any harmlessness
questions for the courts to address on remand.
                        *    *     *
 We conclude that §841’s “knowingly or intentionally”
mens rea applies to the “except as authorized” clause. This
means that in a §841 prosecution in which a defendant
meets his burden of production under §885, the Govern-
16            XIULU RUAN v. UNITED STATES

                     Opinion of the Court

ment must prove beyond a reasonable doubt that the de-
fendant knowingly or intentionally acted in an unauthor-
ized manner. We vacate the judgments of the Courts of Ap-
peals below and remand the cases for further proceedings
consistent with this opinion.
                                          It is so ordered.
                  Cite as: 597 U. S. ____ (2022)            1

                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

SUPREME COURT OF THE UNITED STATES
                          _________________

                   Nos. 20–1410 and 21–5261
                          _________________


               XIULU RUAN, PETITIONER
20–1410                  v.
                   UNITED STATES
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
          APPEALS FOR THE ELEVENTH CIRCUIT



             SHAKEEL KAHN, PETITIONER
21–5261                 v.
                  UNITED STATES
 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE TENTH CIRCUIT
                         [June 27, 2022]

   JUSTICE ALITO, with whom JUSTICE THOMAS joins, and
with whom JUSTICE BARRETT joins as to Parts I–A, I–B, and
II, concurring in the judgment.
   In criminal law, the distinction between the elements of
an offense and an affirmative defense is well-known and
important. In these cases, however, the Court recognizes a
new hybrid that has some characteristics of an element and
some characteristics of an affirmative defense. The conse-
quences of this innovation are hard to foresee, but the result
may well be confusion and disruption. That risk is entirely
unnecessary.
   We granted certiorari in these cases to decide whether a
physician may be convicted of dispensing or distributing
drugs by prescription under a provision of the Controlled
Substances Act of 1970 (CSA), 21 U. S. C. §841(a), if he or
she believed in good faith that the prescription was within
the course of professional practice. In my view, there is a
2              XIULU RUAN v. UNITED STATES

                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

straightforward answer to this question. The CSA contains
an exception for prescriptions issued in the course of profes-
sional practice, and this exception is a carry-over from the
CSA’s predecessor, the Harrison Narcotics Act of 1914, 38
Stat. 785. In interpreting the Harrison Act, this Court held
that a registered physician acts “in the course of his profes-
sional practice” when the physician writes prescriptions “in
good faith.” Linder v. United States, 268 U. S. 5, 17–18
(1925). I would hold that this rule applies under the CSA
and would therefore vacate the judgments below and re-
mand for further proceedings.
  The Court declines to adopt this approach and instead
takes a radical new course. It holds that the mental state
expressed by the terms “knowingly or intentionally” in
§841(a) applies to the provision’s “[e]xcept as authorized”
proviso. It bases this conclusion not on anything in the lan-
guage of the CSA, but instead on the “presumption, tracea-
ble to the common law, that Congress intends to require a
defendant to possess a culpable mental state.” Rehaif v.
United States, 588 U. S. ___, ___ (2019) (slip op., at 3).
  The Court’s analysis rests on an obvious conceptual mis-
take. A culpable mental state—or, to use the traditional
Latin term, “mens rea”—is the mental state an accused
must have in relation to the elements of an offense. But the
authorizations in the CSA that excuse acts that are other-
wise unlawful under §841(a) are not elements of the of-
fenses created by that provision. They are affirmative
defenses. The presumption that elements must be accom-
panied by a culpable mental state—which I will call “the
mens rea canon”—provides no guidance on what a defend-
ant must prove to establish an affirmative defense. And for
that reason, that canon does not help to decide whether
there is a good-faith defense in §841(a) prosecutions of phy-
sicians.
  The Court does not claim that the “[e]xcept as authorized”
                  Cite as: 597 U. S. ____ (2022)              3

                 ALITO,AJ.,   , J., concurring
                            concurring
                         LITO           in judgment

proviso actually constitutes an element of dispensing or dis-
tributing a controlled substance. But it concludes, based on
a vague four-part test, that the proviso is “sufficiently like
an element in respect to the matter at issue here as to war-
rant similar treatment.” Ante, at 12. How many other af-
firmative defenses might warrant similar treatment, the
Court does not say. It leaves prosecutors, defense attor-
neys, and the lower courts in the dark. I cannot accept this
cavalier treatment of an important question.
   Nor can I accept the Court’s conclusion that once a de-
fendant produces evidence that his or her conduct was “au-
thorized,” “the Government must prove beyond a reasona-
ble doubt that the defendant knowingly or intentionally
acted in an unauthorized manner.” Ante, at 5. We did not
grant certiorari on the question of the burden of proof ap-
plicable to authorizations to dispense or distribute con-
trolled substances. No party has briefed this issue, and its
resolution is not essential to our decision in these cases. In
keeping with our normal practice, I would not address this
question. But because the Court volunteers its own answer,
I will offer one as well. As I see it, the text of the CSA does
not show that Congress intended to deviate from the common-
law rule that the burden of proving “affirmative defenses—
indeed, ‘all . . . circumstances of justification, excuse or al-
leviation’—rest[s] on the defendant.” Patterson v. New
York, 432 U. S. 197, 202 (1977) (quoting 4 W. Blackstone
Commentaries *201). And absolutely nothing in the text of
the statute indicates that Congress intended to impose a
burden on the Government to disprove all assertions of au-
thorization beyond a reasonable doubt.
                              I
                              A
  As relevant here, §841(a)(1) provides that “except as au-
thorized by this subchapter, it shall be unlawful for any per-
4                 XIULU RUAN v. UNITED STATES

                   ALITO,AJ.,   , J., concurring
                              concurring
                           LITO           in judgment

son knowingly or intentionally . . . to manufacture, distrib-
ute, or dispense, or possess with intent to manufacture, dis-
tribute, or dispense, . . . a controlled substance.” According
to the Court’s reasoning, the terms “knowingly or intention-
ally” in §841(a)(1) apply to the “except as authorized” pro-
viso at the beginning of the provision. But it is hard to see
how this could be true.
   As a matter of elementary syntax, the adverbs “know-
ingly” and “intentionally” are most naturally understood to
modify the verbs that follow, i.e., “manufacture,” “distrib-
ute,” etc., and not the introductory phrase “except as au-
thorized.” That phrase, in turn, clearly modifies the term
“unlawful.”
   The Court does not suggest otherwise. It does not claim
that “knowingly or “intentionally” modifies the introductory
proviso in a grammatical sense. (If it did, the introductory
phrase would clearly be an element, and for reasons that I
will explain, infra, at 5–6, 21 U. S. C. §885 unmistakably
rules that out.) Instead, the Court pointedly uses different
terminology. It repeatedly says that the phrase “knowingly
or intentionally” “applies” to the introductory phrase, ante,
at 2, 4, 6, 9, 15 (emphasis added). And it reaches this con-
clusion based on grounds that have nothing to do with
grammar or syntax.
   Specifically, the Court relies on a substantive canon of in-
terpretation—the mens rea canon. Under this canon, the
Court interprets criminal statutes to require a mens rea for
each element of an offense “even where ‘the most grammat-
ical reading of the statute’ does not support” that interpre-
tation. Rehaif, 588 U. S., at ___ (slip op., at 6) (quoting
United States v. X-Citement Video, Inc., 513 U. S. 64, 70
(1994)).* But until today, this canon has been applied only
——————
  *Why we have held that the mens rea canon allows courts to ignore
obvious textual evidence of congressional intent is not obvious. In our
constitutional system, it is Congress that has the power to define the
elements of criminal offenses, not the federal courts. Liparota v. United
                      Cite as: 597 U. S. ____ (2022)                       5

                    ALITO,AJ.,   , J., concurring
                               concurring
                            LITO           in judgment

to elements, and the “except as authorized” introductory
phrase in §841(a)(1) is plainly not an element.
   “The definition of the elements of a criminal offense is en-
trusted to the legislature, particularly in the case of federal
crimes, which are solely creatures of statute.” Liparota v.
United States, 471 U. S. 419, 424 (1985). See also Dixon v.
United States, 548 U. S. 1, 7 (2006). But authorization to
dispense or distribute a controlled substance lacks the most
basic features of an element of an offense. For one thing, it
is black-letter law that an indictment must allege “the ele-
ments of the offense charged.” Hamling v. United States,
418 U. S. 87, 117 (1974). So if lack of authorization were an
element, it would be necessary to allege that in every
§841(a)(1) indictment. But §885 says that it is not “neces-
sary for the United States to negative any exemption or ex-
ception set forth in [the relevant subchapter] in any . . . in-
dictment.” Beyond that, the prosecution bears the burden
of producing evidence with respect to every element of a
crime. Patterson, 432 U. S., at 215. But §885(a)(1) also pro-
vides that “the burden of going forward with the evidence
with respect to any such exemption or exception shall be
upon the person claiming its benefit.” It could hardly be

——————
States, 471 U. S. 419, 424 (1985); see also United States v. Davis, 588
U. S. ___, ___ (2019) (slip op., at 5) (“Only the people’s elected represent-
atives in the legislature are authorized to ‘make an act a crime’ ” (quoting
United States v. Hudson, 7 Cranch 32, 34 (1812))). The mens rea canon
is legitimate when it is used to determine what elements Congress in-
tended to include in the definition of an offense. See, e.g., Staples v.
United States, 511 U. S. 600, 605 (1994) (explaining that the canon is
founded on an inference of congressional intent). But applying that
canon to override the intentions of Congress would be inconsistent with
the Constitution’s separation of powers. Federal courts have no consti-
tutional authority to re-write the statutes Congress has passed based on
judicial views about what constitutes “sound” or “just” criminal law. Cf.
X-Citement Video, 513 U. S., at 80–82 (Scalia, J., dissenting) (criticizing
our mens rea canon precedents for “convert[ing a] rule of interpretation
into a rule of law” binding on Congress).
6               XIULU RUAN v. UNITED STATES

                 ALITO,AJ.,   , J., concurring
                            concurring
                         LITO           in judgment

more obvious that Congress did not cast the “except as au-
thorized” introductory proviso as an element of distributing
or dispensing a controlled substance.
   Instead, that proviso clearly creates an affirmative de-
fense—that is, a “justification or excuse which is a bar to
the imposition of criminal liability” on conduct that satisfies
the elements of an offense. 1 W. LaFave, Substantive Crim-
inal Law §1.8(c) (3d ed. 2018). Section 841(a)(1) has two
main parts: a principal clause generally prohibiting “know-
ingly or intentionally” doing certain things with respect to
controlled substances (i.e., manufacturing them, distrib-
uting them, etc.), and a proviso indicating that these acts
are unlawful “except as authorized” by other statutory pro-
visions. As we have long held, the default rule for inter-
preting provisions with this structure is that “ ‘an exception
made by a proviso or other distinct clause’ ” designates an
affirmative defense that the Government has no duty to
“ ‘negative.’ ” Dixon, 548 U. S., at 13 (quoting McKelvey v.
United States, 260 U. S. 353, 357 (1922)); see also United
States v. Dickson, 15 Pet. 141, 165 (1841) (calling this “the
general rule of law which has always prevailed”). When
this rule applies, it is “ ‘incumbent on one who relies on such
an exception to set it up and establish it.’ ” Dixon, 548 U. S.,
at 13 (quoting McKelvey, 260 U. S., at 357).
   The CSA explicitly incorporates this default rule. As
noted, §885(a)(1) provides that the prosecution need not
“negative any exemption or exception set forth in this sub-
chapter in any complaint, information, indictment, or other
pleading or in any trial, hearing, or other proceeding.” (Em-
phasis added.) Short of using the words “affirmative de-
fense,” there is no clearer way of indicating that authoriza-
tion constitutes an affirmative defense.
   On the most natural reading, then, §841(a)(1) creates an
offense that has as its elements (1) knowingly or intention-
ally (2) distributing or dispensing (3) a controlled sub-
stance. The “[e]xcept as authorized” proviso recognizes an
                  Cite as: 597 U. S. ____ (2022)             7

                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

affirmative defense that excuses or justifies conduct that
otherwise would fall within §841(a)(1)’s general prohibition.
The mens rea canon does not speak to the constituents of
that defense.
                              B
  While the Court does not claim that the “[e]xcept as au-
thorized” proviso is an element of a §841(a)(1) offense, the
Court argues that the proviso is “sufficiently like an ele-
ment in respect to the matter at issue here” for the mens
rea canon to apply, ante, at 12. The Court provides four
reasons for this conclusion: “[T]he language of §841 (which
explicitly includes a ‘knowingly or intentionally’ provision);
the crucial role authorization (or lack thereof ) plays in dis-
tinguishing morally blameworthy conduct from socially
necessary conduct; the serious nature of the crime and its
penalties; and the vague, highly general language of the
regulation defining the bounds of prescribing authority.”
Ibid. Not one of these reasons withstands scrutiny.
  “[T]he language of §841.” The Court notes that this pro-
vision expressly sets out a mens rea that applies to the ele-
ments of the offense, ante, at 13, but the vast majority of
criminal statutes share this characteristic. Therefore, this
feature does not set §841 apart.
  “[T]he crucial role authorization (or lack thereof ) plays in
distinguishing morally blameworthy conduct from socially
necessary conduct.” The Court claims that authorization
separates out morally blameworthy innocent conduct; but
something very similar may be said about most, if not all,
affirmative defenses. Take the common-law defense of du-
ress. Duress “excuse[s] criminal conduct where the actor
was under an unlawful threat of imminent death or serious
bodily injury” and the “threat caused the actor to engage in
conduct violating the literal terms of the criminal law.”
United States v. Bailey, 444 U. S. 394, 409 (1980). But a
8              XIULU RUAN v. UNITED STATES

                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

person who acts under duress is not “morally blamewor-
thy”—that is part of what it means to say that duress ex-
cuses otherwise-criminal conduct. Similarly, individuals
who kill or wound another person in self-defense to prevent
their own death or serious injury are not considered morally
blameworthy. No one supposes that these defenses are hy-
brids, or that the mens rea canon is a guide to their content.
    It is unclear why the Court thinks that §841(a)’s affirma-
tive defense is different. There are hints in the Court’s
opinion that it has crafted a special rule for doctors—for ex-
ample, the Court describes their conduct in writing pre-
scriptions as not just “innocent,” but “socially beneficial”
and “socially necessary.” Ante, at 6, 12. But §841(a) is not
a doctor-specific provision. Section 841(a)’s proviso presum-
ably applies in the same way for all §841(a) defendants—
whether they are drug dealers accused of selling heroin or
are physicians charged with abusing their authority to pre-
scribe painkillers.
    “[T]he serious nature of the crime and its penalties.” The
Court also suggests that authorization is “like an element”
because dispensing or distributing a controlled substance is
a felony that carries a substantial sentence. But would all
felonies qualify? If not, where would the Court draw the
line? The Court provides no answers.
    “[T]he vague, highly general language of the regulation
defining prescribing authority.” As the Court explains, the
regulation defining the authority of physicians to prescribe
controlled substances allows them to issue a prescription
“for a legitimate medical purpose . . . in the usual course of
. . . professional practice.” 21 CFR §1306.04(a) (2021). But
§841(a) applies to many other types of violations and many
other categories of defendants. Is the proviso a hybrid ele-
ment/defense only for doctors? Would its status change if
the regulation were reframed in more specific terms? How
can the status of a phrase in a statute depend upon an im-
plementing regulation? The Court provides no answer to
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                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

these or any other questions naturally raised by its ipse
dixit that the exception in §841(a) is “sufficiently like” an
element to require that it be treated as such in some re-
spects but not others.
                               C
   The Court also errs in holding that, if a §841(a)(1) defend-
ant “meets the burden of producing evidence that his or her
conduct was ‘authorized,’ ” the Government has the burden
to “prove beyond a reasonable doubt that the defendant
knowingly or intentionally acted in an unauthorized man-
ner,” ante, at 5. As noted, the common-law rule was that
the defendant had the burden of production and persuasion
on any affirmative defense. And the Court has held that
when Congress does not address the burden of proof in the
text of a statute, “we presume that Congress intended to
preserve the common-law rule.” Smith v. United States,
568 U. S. 106, 112 (2013); see also Dixon, 548 U. S., at 13–
14.
   The Court identifies one and only one reason for deviat-
ing from this background rule—the fact that §885(a)(1)
states that “the burden of going forward with the evidence
with respect to any . . . exemption or exception shall be upon
the person claiming its benefit.” Because this provision
does not say expressly that a defendant also has the burden
of persuasion, the Court infers that Congress meant to al-
locate that burden to the prosecution. That inference is un-
warranted. Section 885(a)(1) explicitly relieves the Govern-
ment of the burden of “negativ[ing]” exceptions “in any
trial.” And it is hard to see how the Government does not
have the burden to “negative” exceptions if it must affirma-
tively disprove a prima facie case of authorization any time
a defendant satisfies the initial burden of production.
   But even if one credits the majority’s assumption that the
CSA partly deviates from the common-law rule by shifting
the burden of persuasion to the Government, the majority’s
10             XIULU RUAN v. UNITED STATES

                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

further holding that the Government must carry that bur-
den with proof “beyond a reasonable doubt” comes out of
thin air. The usual rule is that affirmative defenses must
be proved “by a preponderance of the evidence.” Id., at 17.
But the majority does not identify a single word in
§§841(a)(1), 885(a)(1), or any other provision of the CSA
that even suggests that the statute imposes a burden of dis-
proving authorization defenses beyond a reasonable doubt.
   The only thing that could conceivably justify reading a
reasonable-doubt requirement into a statute that says
nothing on the subject is the principle that an ambiguous
statute must be interpreted, when possible, to avoid uncon-
stitutionality. See A. Scalia & B. Garner, Reading Law: The
Interpretation of Legal Texts 247–251 (2012). But the
Court does not claim that it would be unconstitutional for
Congress to require the Government to prove lack of au-
thorization by only a preponderance of the evidence. In-
deed, the Court does not even claim that it would be uncon-
stitutional to shift the burden of persuasion to the
defendant. Nor could it. Our precedents establish that gov-
ernments are “foreclosed from shifting the burden of proof
to the defendant only ‘when an affirmative defense . . . ne-
gate[s] an element of the crime.’ ” Smith, 568 U. S., at 110
(quoting Martin v. Ohio, 480 U. S. 228, 237 (1987) (Powell,
J., dissenting)). And we have held that when an affirmative
defense instead justifies or “ ‘excuse[s] conduct that would
otherwise be punishable,’ ” the “Government has no consti-
tutional duty to overcome the defense beyond a reasonable
doubt.” 568 U. S., at 110 (quoting Dixon, 548 U. S., at 6).
   The authorization defense made available to prescribing
physicians by the CSA plainly does not negate any of the
defining elements of dispensing or distributing a controlled
substance in violation of §841(a)(1). As a result, the Court
has no basis for reading a requirement to disprove authori-
zation into the CSA. And at a minimum, even if the Gov-
ernment must bear the ultimate burden of persuasion once
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                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

the burden of production is satisfied, the CSA should be
read to preserve a traditional preponderance-of-the-
evidence standard for authorization defenses.
                               II
   My analysis thus far establishes that authorization is an
affirmative defense to liability under §841(a)(1), and the
constituents of that defense cannot be identified through
brute-force application of a canon designed to identify the
elements of an offense. In my view, the contours of that
defense can be elucidated only by examining the text, struc-
ture, and history of the provisions of the CSA that define it.
I turn to that task now.
   The authorization relied on by the petitioners in these
cases permits physicians registered with the federal Drug
Enforcement Administration to prescribe controlled sub-
stances to patients by prescription. §§822(b), 823(f ), 829(a).
As we have previously interpreted it, this authorization
does not allow physicians to dispense controlled substances
by prescription for any reason they choose; instead, the au-
thorization “is limited to the dispensing and use of drugs ‘in
the course of professional practice or research.’ ” United
States v. Moore, 423 U. S. 122, 141 (1975) (quoting §802(20)
(1970 ed.)).
   The notion of action taken “in the course of professional
practice” is not defined in the CSA, but our precedents hold
that when Congress employs a term of art “obviously trans-
planted from another legal source,” it “brings the old soil
with it.” George v. McDonough, 596 U. S. ___, ___ (2022)
(slip op., at 5) (quoting Taggart v. Lorenzen, 587 U. S. ___,
___ (2019) (slip op., at 5); internal quotation marks omit-
ted). And the notion that a prescription is authorized if it
is issued in the course of professional practice is directly
traceable to the Harrison Act, which prohibited “any per-
son” from distributing or dispensing coca leaves or opium
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                 ALITO,AJ.,   , J., concurring
                            concurring
                         LITO           in judgment

“except in pursuance of a written order” issued by a practi-
tioner “in the course of his professional practice only.” §2,
38 Stat. 786. Arguably, the phrase “in the course of . . . pro-
fessional practice” could have been read to refer only to con-
duct that conforms to the standards of medical practice as
a purely objective matter. But our Harrison Act precedents
interpreted that phrase to refer to “bona fide medical prac-
tice,” which meant that any prescription issued “in good
faith” qualified as an authorized act of dispensing one of the
drugs proscribed by the statute. Linder, 268 U. S., at 17–
18; see also Boyd v. United States, 271 U. S. 104, 107 (1926);
Webb v. United States, 249 U. S. 96, 99 (1919).
   Nothing in the CSA suggests that Congress intended to
depart from the preexisting understanding of action “in the
course of professional practice.” We have previously held
that the CSA incorporates settled understandings of “the
exemption given to doctors” to dispense controlled sub-
stances “ ‘in the course of . . . professional practice’ ” under
the Harrison Act. Moore, 423 U. S., at 139–140 (quoting 38
Stat. 786). And the language of the CSA supports the same
conclusions that we previously reached about the Harrison
Act. As our CSA precedents have explained, to act “in the
course of professional practice” is to engage in the practice
of medicine—or, as we have put it, to “act ‘as a physician.’ ”
Moore, 423 U. S., at 141. For a practitioner to “practice
medicine,” he or she must act for a medical purpose—which
means aiming to prevent, cure, or alleviate the symptoms
of a disease or injury—and must believe that the treatment
is a medically legitimate means of treating the relevant dis-
ease or injury.
   But acting “as a physician” does not invariably mean act-
ing as a good physician, as an objective understanding of
the “in the course of professional practice” standard would
suggest. A doctor who makes negligent or even reckless
mistakes in prescribing drugs is still “acting as a doctor”—
he or she is simply acting as a bad doctor. The same cannot
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                ALITO,AJ.,   , J., concurring
                           concurring
                        LITO           in judgment

be said, however, when a doctor knowingly or purposefully
issues a prescription to facilitate “addiction and recrea-
tional abuse,” Gonzales v. Oregon, 546 U. S. 243, 274 (2006).
Objectives of that kind are alien to medical practice, and a
doctor who prescribes drugs for those purposes is not “act-
ing as a physician” in any meaningful sense.
   I would thus hold that a doctor who acts in subjective
good faith in prescribing drugs is entitled to invoke the
CSA’s authorization defense. Under the correct under-
standing of that defense, a doctor acts “in the course of pro-
fessional practice” in issuing a prescription under the CSA
if—but only if—he or she believes in good faith that the pre-
scription is a valid means of pursuing a medical purpose. A
doctor who knows that he or she is acting for a purpose for-
eign to medicine—such as facilitating addiction or recrea-
tional drug abuse—is not protected by the CSA’s authoriza-
tion to distribute controlled substances by prescription.
Such doctors may be convicted of unlawfully distributing or
dispensing a controlled substance under §841(a)(1).
   Based on this holding, I would vacate the judgments of
the Courts of Appeals below. And like the Court, I would
leave it to those courts to determine on remand whether the
instructions provided in petitioners’ respective trials ade-
quately described the good-faith defense and whether any
errors in the instructions were harmless.