Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-1410_1an2.pdf
Page Number: 30

10 

XIULU RUAN v. UNITED STATES 

ALITO, J., concurring
ALITO, J., concurring 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