Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/558bv.pdf
Page Number: 168.0

Cite as: 558 U. S. 4 (2009) 

7 

Per Curiam 

agree  with  the  Court  of  Appeals  that  Van  Hook  is  entitled 
to relief. 

A 

The Sixth Amendment entitles criminal defendants to the 
“ ‘effective  assistance  of  counsel’ ”—that  is,  representation 
that does not fall “below an objective standard of reasonable­
ness”  in  light  of  “prevailing  professional  norms.”  Strick­
land  v.  Washington,  466  U. S.  668,  686,  688  (1984)  (quoting 
McMann  v.  Richardson,  397  U. S.  759,  771,  n.  14  (1970)). 
That  standard  is  necessarily  a  general  one.  “No  particular 
set  of  detailed  rules  for  counsel’s  conduct  can  satisfactorily 
take account of the variety of circumstances faced by defense 
counsel  or  the  range  of  legitimate  decisions  regarding  how 
best  to  represent  a  criminal  defendant.”  466  U. S.,  at  688– 
689.  Restatements  of  professional  standards,  we  have  rec­
ognized,  can  be  useful  as  “guides”  to  what  reasonableness 
entails, but only to the extent they describe the professional 
norms  prevailing  when  the  representation  took  place.  Id., 
at 688. 

The  Sixth  Circuit  ignored  this  limiting  principle,  relying 
on ABA guidelines announced 18 years after Van Hook went 
to trial.  See 560 F. 3d, at 526–528 (quoting ABA Guidelines 
for the Appointment and Performance of Defense Counsel in 
Death  Penalty  Cases  10.7,  comment.,  pp.  81–83  (rev.  ed. 
2003)).  The  ABA  standards  in  effect  in  1985  described  de­
fense counsel’s duty to investigate both the merits and miti­
gating circumstances in general terms: “It is the duty of the 
lawyer  to  conduct  a  prompt  investigation  of  the  circum­
stances of the case and to explore all avenues leading to facts 
relevant  to  the  merits  of  the  case  and  the  penalty  in  the 
event of conviction.”  1 ABA Standards for Criminal Justice 
4–4.1,  p.  4–53  (2d  ed.  1980).  The  accompanying  two-page 
commentary  noted  that  defense  counsel  have  “a  substantial 
and important role to perform in raising mitigating factors,” 
and  that  “[i]nformation  concerning  the  defendant’s  back­
ground, education, employment record, mental and emotional