Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-826_p702.pdf
Page Number: 19

Cite as:  596 U. S. ____ (2022) 

15 

Opinion of the Court 

This theory is mistaken.  Proof of prejudice under Brecht 
does not equate to a successful showing under AEDPA.  In-
stead,  the  inquiries  are  “entirely  different  in  kind.”
J. Greabe, The Riddle of Harmless Error Revisited, 54 Hou-
ston L. Rev. 59, 113, n. 297 (2016) (emphasis deleted).  They
pose courts with different questions to resolve and require 
courts  to  answer  those  questions  based  on  different  legal 
materials. 

Take the questions the two tests pose.  When a state court 
has applied Chapman, § 2254(d)(1) requires a habeas peti-
tioner to prove that the state court’s decision was unreason-
able.  Cullen v. Pinholster, 563 U. S. 170, 181 (2011); Fry, 
551  U. S.,  at  119.    To  accomplish  that,  a  petitioner  must 
persuade a federal court that no “fairminded juris[t]” could
reach the state court’s conclusion under this Court’s prece-
dents.  Ayala, 576 U. S., at 269 (internal quotation marks 
omitted).  Similarly, if a petitioner alleges the state court’s
decision  “was  based  on  an  unreasonable  determination  of 
the facts” under § 2254(d)(2), it is not enough to show that
“reasonable  minds  reviewing  the  record  might  disagree
about the finding in question.”  Brumfield v. Cain, 576 U. S. 
305,  314  (2015)  (internal  quotation  marks  and  alteration 
omitted).  By contrast, under Brecht a petitioner may pre-
vail by persuading a federal court that it alone should har-
bor “grave doubt”—not absolute certainty—about whether
the  trial  error  affected  the  verdict’s  outcome.    O’Neal  v. 
McAninch,  513  U. S.  432,  435  (1995).    In  sum,  where 
AEDPA asks whether every fairminded jurist would agree 
that an error was prejudicial, Brecht asks only whether a
federal  habeas  court  itself  harbors  grave  doubt  about  the 
petitioner’s verdict.

Next,  consider  the  legal  materials  a  court  may  consult
when applying the two tests.  Section 2254(d)(1) limits ha-
beas relief to cases where a state-court decision contravenes 
or unreasonably applies “clearly established Federal law, as
determined by the Supreme Court of the United States.”  It