Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/558bv.pdf
Page Number: 205.0

44 

PORTER  v.  McCOLLUM 

Per Curiam 

the intense stress and mental and emotional toll that combat 
took on Porter.9  The evidence that he was AWOL is consist­
ent  with  this  theory  of  mitigation  and  does  not  impeach  or 
diminish the evidence of his service.  To conclude otherwise 
reﬂects  a  failure  to  engage  with  what  Porter  actually  went 
through in Korea. 

As  the  two  dissenting  justices  in  the  Florida  Supreme 
Court  reasoned,  “there  exists  too  much  mitigating  evidence 
that was not presented to now be ignored.”  Id., at 937 (An-
stead,  J.,  concurring  in  part  and  dissenting  in  part).  Al­
though the burden is on petitioner to show he was prejudiced 
by his counsel’s deﬁciency, the Florida Supreme Court’s con­
clusion that Porter failed to meet this burden was an unrea­
sonable  application  of  our  clearly  established  law.  We  do 
not require a defendant to show “that counsel’s deﬁcient con­
duct more likely than not altered the outcome” of his penalty 
proceeding,  but  rather  that  he establish  “a  probability  sufﬁ­
cient  to  undermine  conﬁdence  in  [that]  outcome.”  Strick­
land, 466 U. S., at 693–694.  This Porter has done. 

The  petition for  certiorari  is granted  in  part,  and the  mo­
tion for leave to proceed in forma pauperis is granted.  The 
judgment  of  the  Court  of  Appeals  is  reversed,  and  the  case 
is  remanded  for  further  proceedings  consistent  with  this 
opinion. 

It is so ordered. 

9 Cf.  Cal.  Penal  Code  Ann.  § 1170.9(a)  (West  Supp.  2009)  (providing  a 
special  hearing  for  a  person  convicted  of  a  crime  “who  alleges  that  he  or 
she  committed  the  offense  as  a  result  of  post-traumatic  stress  disorder, 
substance  abuse,  or  psychological  problems  stemming  from  service  in  a 
combat theater in the United States military”); Minn. Stat. § 609.115, Subd. 
10 (2008) (providing for a special process at sentencing if the defendant is 
a  veteran  and  has  been  diagnosed  as  having  a  mental  illness  by  a  quali­
ﬁed psychiatrist).