That’s why the Wisconsin case is
unprecedented. The Campaign Legal
Center is proposing a multistep test to
evaluate whether a map is skewed so far
as to be unconstitutional. Such a test
hasn’t been presented to the Supreme
Court before. Part of the test relies on a
simple calculation, called the efficiency-
gap equation, to determine how easy it
is for each party to translate votes into
seats. If a state’s efficiency gap is an
outlier by historical standards, it would
fail that part of the test.
This is not the only test being
developed. Political scientists and
statisticians are looking at various
ways to fight gerrymandering using
the same computer-aided analysis
that empowered it. Researchers at
the University of Illinois at Urbana-
Champaign are using computers
to create millions of simulations of
“reasonably imperfect” legislative maps
that can be compared with the ones
lawmakers draw up to help determine
whether they are gerrymandered.
Organizers at Tufts University trained
mathematicians at a workshop this
summer to serve as expert witnesses on
court cases fighting gerrymandering.If the high court rules against the
Wisconsin map, the test could have a
nationwide impact starting in 2020,
when the next Census kicks off a
new round of mapmaking. Nicholas
Stephanopoulos, a law professor at
the University of Chicago who helped
develop the test, says it would not
eliminate all gerrymandering but would
cut off the most egregious plans.
“There are places where [voters are]
50-50, yet one party is locked out of
power,” Stephanopoulos says. “There is
no other practice or policy that has such
an impact on who is elected.” □Who gets
more seats?
It’s not just state
legislatures that
are affected by
gerrymandering.
Both parties have
used the tactic
to gain seats in
the U.S. House.
Partisan bias netted
the GOP 17 to
29 extra seats in
2016.REDRAWN BOUNDARIES
The new map siphoned urban
Democrats into suburban districts that
had large numbers of Republicans.ADVANTAGE MAJORITY
Red voters control each district. Blue
voters have no representation.ADVANTAGE MINORITY
Blue voters have greater representation than red voters. This is
done using two strategies, called cracking and packing.Cracking
dilutes the
voting power
of the red
party across
several
districts. The
blue minority
party wins by
slim margins
in those
areas.Packing
concentrates
the red voters
into just a
few districts.
They win by
large margins
in those
areas but
have less
voting power
elsewhere.NOTE: MAP EXCLUDES STATES WITH FIVE
OR FEWER CONGRESSIONAL DISTRICTS.
THE STATES SHOWN HERE ACCOUNT FOR
85% OF ALL CONGRESSIONAL DISTRICTS.SOURCES: THE CAMPAIGN LEGAL CENTER; COURT FILINGS; BALLOTPEDIA; THE BRENNAN CENTER FOR JUSTICE
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