Document ID: ./input/supremecourt_opinions/opinions/10pdf/09-1233.pdf
Page Number: 49

Cite as:  563 U. S. ____ (2011) 

43 

Opinion of the Court 

According  to  the  State,  this  testimony  expressed  the
witnesses’ policy preferences, rather than their views as to
what  would  cure  the  constitutional  violation.    Of  course, 
courts  must  not  confuse  professional  standards  with  con-
stitutional  requirements.  Rhodes  v.  Chapman,  452  U. S. 
337, 348, n. 13 (1981).  But expert opinion may be relevant 
when determining what is obtainable and what is accept-
able  in  corrections  philosophy.  See  supra,  at  37–38. 
Nothing  in  the  record  indicates  that  the  experts  in  this 
case  imposed  their  own  policy  views  or  lost  sight  of  the
underlying  violations.    To  the  contrary,  the  witnesses 
testified  that  a  130%  population  limit  would  allow  the
State to remedy the constitutionally inadequate provision
of  medical  and  mental  health  care.    When  expert  opinion 
is addressed to the question of how to remedy the relevant
constitutional violations, as it was here, federal judges can
give it considerable weight.

The Federal Bureau of Prisons (BOP) has set 130% as a
long-term  goal  for  population  levels  in  the  federal  prison 
system.  Brief  for  Appellants  43–44.    The  State  suggests
the  expert  witnesses  impermissibly  adopted  this  profes-
sional  standard  in  their  testimony.    But  courts  are  not 
required  to  disregard  expert  opinion  solely  because  it 
adopts  or  accords  with  professional  standards.    Profes-
sional  standards  may  be  “helpful  and  relevant  with  re-
spect to some questions.”  Chapman, supra, at 348, n. 13. 
The witnesses testified that a limit of 130% was necessary 
to remedy the constitutional violations, not that it should 
be adopted because it is a BOP standard.  If anything, the
fact that the BOP views 130% as a manageable population
density  bolsters  the  three-judge  court’s  conclusion  that  a
population  limit  of  130%  would  alleviate  the  pressures 
associated with overcrowding and allow the State to begin 
to provide constitutionally adequate care.

Although  the  three-judge  court  concluded  that  the  “evi-
dence  in  support  of  a  130%  limit  is  strong,”  it  found  that