Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-1410_1an2.pdf
Page Number: 19.0

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-

*