Document ID: ./input/supremecourt_opinions/opinions/14pdf/13-1041_0861.pdf
Page Number: 29.0

Cite as:  575 U. S. ____ (2015) 

5 

THOMAS, J., concurring in judgment
 

II
 
We  have  not  always  been  vigilant  about  protecting  the
structure  of  our  Constitution.    Although  this  Court  has
repeatedly  invoked  the  “separation  of  powers”  and  “the 
constitutional  system  of  checks  and  balances”  as  core
principles  of  our  constitutional  design,  essential  to  the
protection of individual liberty, see, e.g., Stern v. Marshall, 
564 U. S. ___, ___–___ (2011) (slip op., at 16–17) (internal
quotation  marks  omitted),  it  has  also  endorsed  a  “more 
pragmatic,  flexible  approach”  to  that  design  when  it  has
seemed more convenient to permit the powers to be mixed, 
see,  e.g.,  Nixon  v.  Administrator  of  General  Services,  433 
U. S. 425, 442 (1977).  As the history shows, that approach 
runs 
the  risk  of  compromising  our  constitutional 
structure. 

A 
The Constitution’s particular blend of separated powers
and  checks  and  balances  was  informed  by  centuries  of 
political  thought  and  experiences.  See  M.  Vile,  Constitu-
tionalism  and  the  Separation  of  Powers  38,  168–169  (2d 
ed. 1998) (Vile).  Though the theories of the separation of 
powers and checks and balances have roots in the ancient
world,  events  of  the  17th  and  18th  centuries  played  a 
crucial  role  in  their  development  and  informed  the  men
who crafted and ratified the Constitution. 

Over  a  century  before  our  War  of  Independence,  the
English Civil War catapulted the theory of the separation 
of powers to prominence.  As political theorists of the day 
witnessed  the  conflict  between  the  King  and  Parliament,
and  the  dangers  of  tyrannical  government  posed  by  each,
they began to call for a clear division of authority between 
the  two.  Id.,  at  44–45,  48–49.  A  1648  work  titled  The 
Royalist’s  Defence  offered  perhaps  the  first  extended 
account  of  the  theory  of  the  separation  of  powers:
“[W]hilst  the  Supreamacy,  the  Power  to  Judge  the  Law,