(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, distribute, 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 separately 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 defendant 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 defendant 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, refers 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 presumption applies with equal or greater force” to the scope of that provision. 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 intentionally.” 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 regulatory 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 “overdeterrence,” i.e., punishing 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 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 separating 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 separate 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 correctly note that the statutory clauses in the cases just described set 

forth elements of an offense. Here, the Government and the concurrence 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 “negative 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 statutory exception in each Controlled Substances Act prosecution. Section 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 scienter requirements. At the same time, the factors discussed above— 

the language of §841; the crucial role authorization plays in distinguishing morally blameworthy conduct from socially necessary conduct; 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 “except as authorized” clause. And the Government does not deny that, 

once a defendant satisfies his burden of production under §885 by invoking 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 “objective honest-effort standard.” Brief for United States 16–17. But 

§841 uses the words “knowingly or intentionally,” not “good faith,” “objectively,” “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 analogous 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 Government 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 doctor knowingly or intentionally acted not “as authorized” will allow badapple 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 instructions 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, Washington, 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 authorized[,] . . . for any person knowingly or intentionally . . . 

to manufacture, distribute, or dispense . . . a controlled substance,” 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 regulation, 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 convicted 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 authorization. After a defendant produces evidence that he or she 

was authorized to dispense controlled substances, the Government must prove beyond a reasonable doubt that the defendant 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 particular, the question concerns the defendant’s state of mind. 

To prove that a doctor’s dispensation of drugs via prescription 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 intended that the prescription was unauthorized? 

Petitioners Xiulu Ruan and Shakeel Kahn are both doctors who actively practiced medicine. They both possessed

licenses permitting them to prescribe controlled substances. The Government separately charged them with 

unlawfully dispensing and distributing drugs in violation of 

§841. Each proceeded to a jury trial, and each was convicted 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 professional 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 standard. 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 subjectively knew that his prescriptions fell outside the scope of 

his prescribing authority. The District Court, however, rejected this request. The court instead set forth a more objective standard, instructing the jury that a doctor acts lawfully 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 convicted 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 substance” 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; alteration 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 attempt to act in accordance with what a reasonable physician 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 generally recognized and accepted standards of practice.” Ibid. 

The court also told the jury that “good faith” was a “complete defense” because it “would be inconsistent with knowingly and intentionally distributing and/or dispensing controlled 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) issued 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 authorized[,] . . . for any person knowingly or intentionally . . . 

to manufacture, distribute, or dispense . . . a controlled substance.” We now hold that §841’s “knowingly or intentionally” mens rea applies to the “except as authorized” clause. 
 

Cite as: 597 U. S. ____ (2022) 5 

Opinion of the Court 

This means that 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 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 punish 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 conscious to be criminal.’” Elonis v. United States, 575 U. S. 

723, 734 (2015) (quoting Morissette, 342 U. S., at 252). Indeed, 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 defendant 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 provision whatsoever—“‘that mens rea which is necessary to separate wrongful conduct from “otherwise innocent conduct.”’” 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). Unsurprisingly, 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 instead “includes a general scienter provision,” “the presumption 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 normally would not view such dispensations as inherently illegitimate; 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 innocent conduct—and, in the case of doctors, socially beneficial conduct—from wrongful conduct. X-Citement Video, 

513 U. S., at 73. Applying §841’s “knowingly or intentionally” mens rea to the authorization clause thus “helps advance the purpose of scienter, for it helps to separate wrongful from innocent acts.” Rehaif, 588 U. S., at ___ (slip op., 
Cite as: 597 U. S. ____ (2022) 7 

Opinion of the Court 

at 6); see also X-Citement Video, 513 U. S., at 72–73. 

In addition, the regulatory language defining an authorized 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 individual practitioner acting in the usual course of his professional practice”). The conduct prohibited by such language

(issuing invalid prescriptions) is thus “often difficult to distinguish from the gray zone of socially acceptable . . . conduct” (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 acceptable 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 regulatory or public welfare offense that carries only minor penalties. 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 
 

 

8 XIULU RUAN v. UNITED STATES 

Opinion of the Court 

States v. Yermian, 468 U. S. 63, 68–69 (1984). To the contrary, 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 Liparota, we interpreted a statute penalizing anyone who

“‘knowingly uses [food stamps] in any manner not authorized by’” statute. 471 U. S., at 420. We held that “knowingly” 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 unambiguously” 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 “‘knowingly receives’” videos “‘involv[ing] the use of a minor engaging 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 anyone who “knowingly violates” a separate subsection. 588 

U. S., at ___–___ (slip op., at 3–4). This latter subsection 
 

Cite as: 597 U. S. ____ (2022) 9 

Opinion of the Court 

made it “unlawful” for people with certain statuses (i.e., being 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 subsection. Id., at ___ (slip op., at 5). To convict under the 

statute, then, the Government had to prove that a defendant 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 requirements, the possession of a gun can be entirely innocent.” 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.” (Emphasis 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 defendant’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 language at issue in the cases we have just described set forth 

elements of the offense. Here, the Government and the concurrence say, the “except as authorized” clause does not set

forth an element. See, e.g., post, at 4–7 (ALITO, J., concurring 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 element, both of which rely on a different provision of the Controlled Substances Act—§885. Section 885 says that the 

Government need not “negative”—i.e., refute—“any exemption or exception . . . in any complaint, information, indictment, 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 indictment must set forth all elements of the charged crime). 

Section 885 also says that the Government need not “negative 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. Patterson 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 requirements. The first has to do with the indictment. It simply

says that the Government need not set forth in an indictment a lack of authorization, or otherwise allege that a defendant does not fall within the many exceptions and exemptions that the Controlled Substances Act contains. The 

Act excepts, for example, licensed professionals such as 

dentists, veterinarians, scientific investigators, and pharmacists from the prohibition on dispensing controlled substances. See 21 U. S. C. §802(21). The Act also excepts employees of drug manufacturers, common carriers, and 

people with sick family members or pets from the prohibition on possessing controlled substances. See §§802(27),

822(c). Section 885 merely absolves the Government of having 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 prosecution. 

Section 885’s second purpose refers only to “the burden of 

going forward with the evidence,” i.e., the burden of production. 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. Director, Office of Workers’ Compensation Programs v. Greenwich Collieries, 512 U. S. 267, 274 (1994) (“our opinions consistently distinguis[h] between burden of proof, which we

defined as burden of persuasion, and . . . the burden of production 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 device, akin to others we have recognized in the criminal context, 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 prohibit the use of a . . . procedural device that shifts to a defendant the burden of producing some evidence contesting 

a fact that may otherwise be inferred, provided the prosecution retains the ultimate burden of proof ”); 1 W. LaFave, 

Substantive Criminal Law §1.8(a), p. 102 (3d ed. 2018) (similar). In a §841 prosecution, then, once the defendant satisfies the initial burden of production by producing evidence

of authorization, the burden of proving a lack of authorization 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, ordinary and longstanding scienter requirements. At the same 

time, the language of §841 (which explicitly includes a

“knowingly or intentionally” provision); the crucial role authorization (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 normal scienter principles to the “except as authorized” clause. 

That statutory requirement, while differing from an element in some respects, is sufficiently like an element in respect to the matter at issue here as to warrant similar legal 

treatment. 

And the Government does not deny that, once a defendant claims that he or she falls within the authorization exception and the burden shifts back to the Government, the

Government must prove a lack of authorization by satisfying 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 advanced 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 authorization 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 authorization 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 “knowingly or intentionally.” It nowhere uses words such as “good 

faith,” “objectively,” “reasonable,” or “honest effort.”

For another, the Government’s standard would turn a defendant’s criminal liability on the mental state of a hypothetical “reasonable” doctor, not on the mental state of the 

defendant himself or herself. Cf. id., at 24 (Government arguing 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 requirement. 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 person’ regards the communication as a threat—regardless of 

what the defendant thinks—reduces culpability on the allimportant element of the crime to negligence.” Id., at 738 

(some internal quotation marks omitted). “[A]nd,” we emphasized, “we ‘have long been reluctant to infer that a negligence 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 Government’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 before us here regarding the mens rea required to convict under the statute. 

Further, the Government, citing Yermian, notes that the 

authorization clause precedes the words “knowingly or intentionally.” 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 scienter 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 authorized will allow bad-apple doctors to escape liability by 

claiming idiosyncratic views about their prescribing authority. 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 bases similar to those we have set forth in Part II of this opinion. See, e.g., Rehaif, 588 U. S., at ___ (slip op., at 8); Liparota, 471 U. S., at 433–434. 

We do the same here. The Government, of course, can 

prove knowledge of a lack of authorization through circumstantial 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., dissenting) (“The use of the word ‘legitimate’ connotes an objective 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 defendant’s “asserted beliefs or misunderstandings are,” especially 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 conviction 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 defendant knowingly or intentionally acted in an unauthorized manner. We vacate the judgments of the Courts of Appeals below and remand the cases for further proceedings

consistent with this opinion. 

It is so ordered. 
ALITO, J., concurring

_________________ 

_________________ 

Cite as: 597 U. S. ____ (2022) 1 

ALITO, J., concurring 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 consequences 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 
 

 

ALITO, J., concurring

2 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

straightforward answer to this question. The CSA contains 

an exception for prescriptions issued in the course of professional 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 professional 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 remand 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 language of the CSA, but instead on the “presumption, traceable 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 mistake. 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 otherwise unlawful under §841(a) are not elements of the offenses created by that provision. They are affirmative 

defenses. The presumption that elements must be accompanied by a culpable mental state—which I will call “the 

mens rea canon”—provides no guidance on what a defendant 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 physicians. 

The Court does not claim that the “[e]xcept as authorized” 
 

ALITO, J., concurring

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ALITO, J., concurring in judgment 

proviso actually constitutes an element of dispensing or distributing 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 warrant similar treatment.” Ante, at 12. How many other affirmative defenses might warrant similar treatment, the 

Court does not say. It leaves prosecutors, defense attorneys, 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 defendant produces 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.” Ante, at 5. We did not 

grant certiorari on the question of the burden of proof applicable to authorizations to dispense or distribute controlled 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 commonlaw rule that the burden of proving “affirmative defenses—

indeed, ‘all . . . circumstances of justification, excuse or alleviation’—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 authorization beyond a reasonable doubt. 

I 

A 

As relevant here, §841(a)(1) provides that “except as authorized by this subchapter, it shall be unlawful for any per-
 

ALITO, J., concurring

4 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

son knowingly or intentionally . . . to manufacture, distribute, or dispense, or possess with intent to manufacture, distribute, or dispense, . . . a controlled substance.” According 

to the Court’s reasoning, the terms “knowingly or intentionally” in §841(a)(1) apply to the “except as authorized” proviso 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 “knowingly” and “intentionally” are most naturally understood to 

modify the verbs that follow, i.e., “manufacture,” “distribute,” etc., and not the introductory phrase “except as authorized.” 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 conclusion based on grounds that have nothing to do with 

grammar or syntax.

Specifically, the Court relies on a substantive canon of interpretation—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 grammatical reading of the statute’ does not support” that interpretation. 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 
ALITO, J., concurring

Cite as: 597 U. S. ____ (2022) 5 

ALITO, J., concurring 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 entrusted 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 elements 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 “necessary for the United States to negative any exemption or exception set forth in [the relevant subchapter] in any . . . indictment.” 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 provides 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 representatives 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 intended 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 constitutional 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). 
 

ALITO, J., concurring

6 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

more obvious that Congress did not cast the “except as authorized” introductory proviso as an element of distributing

or dispensing a controlled substance.

Instead, that proviso clearly creates an affirmative defense—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 Criminal Law §1.8(c) (3d ed. 2018). Section 841(a)(1) has two

main parts: a principal clause generally prohibiting “knowingly or intentionally” doing certain things with respect to 

controlled substances (i.e., manufacturing them, distributing them, etc.), and a proviso indicating that these acts 

are unlawful “except as authorized” by other statutory provisions. As we have long held, the default rule for interpreting 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 subchapter in any complaint, information, indictment, or other

pleading or in any trial, hearing, or other proceeding.” (Emphasis added.) Short of using the words “affirmative defense,” there is no clearer way of indicating that authorization constitutes an affirmative defense. 

On the most natural reading, then, §841(a)(1) creates an 

offense that has as its elements (1) knowingly or intentionally (2) distributing or dispensing (3) a controlled substance. The “[e]xcept as authorized” proviso recognizes an 
 

 

 

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ALITO, J., concurring 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 authorized” proviso is an element of a §841(a)(1) offense, the 

Court argues that the proviso is “sufficiently like an element 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 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.” 

Ibid. Not one of these reasons withstands scrutiny. 

“[T]he language of §841.” The Court notes that this provision expressly sets out a mens rea that applies to the elements 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 duress. 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 
 

ALITO, J., concurring

8 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

person who acts under duress is not “morally blameworthy”—that is part of what it means to say that duress excuses 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 hybrids, or that the mens rea canon is a guide to their content.

It is unclear why the Court thinks that §841(a)’s affirmative defense is different. There are hints in the Court’s 

opinion that it has crafted a special rule for doctors—for example, the Court describes their conduct in writing prescriptions 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 presumably 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 prescribe 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 element/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 implementing regulation? The Court provides no answer to 
ALITO, J., concurring

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ALITO, J., concurring 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 respects but not others. 

C 

The Court also errs in holding that, if a §841(a)(1) defendant “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 manner,” 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 deviating 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 allocate that burden to the prosecution. That inference is unwarranted. Section 885(a)(1) explicitly relieves the Government 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 affirmatively 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 
 

ALITO, J., concurring

10 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

further holding that the Government must carry that burden 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 disproving 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 unconstitutionality. 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 authorization by only a preponderance of the evidence. Indeed, the Court does not even claim that it would be unconstitutional to shift the burden of persuasion to the 

defendant. Nor could it. Our precedents establish that governments are “foreclosed from shifting the burden of proof 

to the defendant only ‘when an affirmative defense . . . negate[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 constitutional 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 authorization into the CSA. And at a minimum, even if the Government must bear the ultimate burden of persuasion once 
 

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ALITO, J., concurring in judgment 

the burden of production is satisfied, the CSA should be 

read to preserve a traditional preponderance-of-theevidence 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, structure, 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 substances 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 authorization “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 transplanted 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 omitted). 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 person” from distributing or dispensing coca leaves or opium 
 

ALITO, J., concurring

12 XIULU RUAN v. UNITED STATES 

ALITO, J., concurring in judgment 

“except in pursuance of a written order” issued by a practitioner “in the course of his professional practice only.” §2, 

38 Stat. 786. Arguably, the phrase “in the course of . . . professional practice” could have been read to refer only to conduct 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 practice,” 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 substances “‘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 disease or injury. 

But acting “as a physician” does not invariably mean acting 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 
 

 

ALITO, J., concurring

Cite as: 597 U. S. ____ (2022) 13 

ALITO, J., concurring in judgment 

be said, however, when a doctor knowingly or purposefully 

issues a prescription to facilitate “addiction and recreational 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 “acting 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 understanding of that defense, a doctor acts “in the course of professional practice” in issuing a prescription under the CSA 

if—but only if—he or she believes in good faith that the prescription is a valid means of pursuing a medical purpose. A 

doctor who knows that he or she is acting for a purpose foreign to medicine—such as facilitating addiction or recreational drug abuse—is not protected by the CSA’s authorization 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 adequately described the good-faith defense and whether any 

errors in the instructions were harmless.