Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-1161_dc8f.pdf
Page Number: 10

6 

GILL v. WHITFORD 

Opinion of the Court 

with  Democrats  needing  54%  of  the  statewide  vote  to
secure a majority in the legislature.  Id., at 852. 

Finally,  the  parties  presented  testimony  from  four  ex­
pert witnesses.  The plaintiffs’ experts, Professor Kenneth
Mayer  and  Professor  Simon  Jackman,  opined  that—
according to their efficiency-gap analyses—the Act 43 map
would systematically favor Republicans for the duration of
the decade.  See id., at 859–861.  The defendants’ experts,
Professor Nicholas Goedert and Sean Trende, opined that 
efficiency  gaps  alone  are  unreliable  measures  of  durable 
partisan  advantage,  and  that  the  political  geography  of 
Wisconsin  currently  favors  Republicans  because  Demo­
crats—who tend to be clustered in large cities—are ineffi­
ciently distributed in many parts of Wisconsin for purposes
of winning elections.  See id., at 861–862. 

At the  close of evidence, the District Court concluded— 
over  the  dissent  of  Judge  Griesbach—that  the  plaintiffs
had  proved  a  violation  of  the  First  and  Fourteenth
Amendments.  The  court  set  out  a  three-part  test  for 
identifying unconstitutional gerrymanders: A redistricting
map violates the First Amendment and the Equal Protec­
tion  Clause  of  the  Fourteenth  Amendment  if  it  “(1)  is
intended to place a severe impediment on the effectiveness 
of  the  votes  of  individual  citizens  on  the  basis  of  their 
political  affiliation,  (2)  has  that  effect,  and  (3)  cannot  be
justified  on  other,  legitimate  legislative  grounds.” 
Id., 
at 884. 

The court went on to find, based on evidence concerning 
the manner in which Act 43 had been adopted, that “one of
the purposes of Act 43 was to secure Republican control of
the Assembly under any likely future electoral scenario for
the  remainder  of  the  decade.”    Id.,  at  896.    It  also  found 
that  the  “more  efficient  distribution  of  Republican  voters
has  allowed  the  Republican  Party  to  translate  its  votes
into seats with significantly greater ease and to achieve—
and  preserve—control  of  the  Wisconsin  legislature.”    Id.,