Gerrymandering Case, Informed by Stephanopoulos's "Efficiency Gap," Heads to Supreme Court

‘Pivotal Moment’ for Democrats? Gerrymandering Heads to Supreme Court
Michael Wines
The New York Times
April 21, 2017

A bipartisan group of voting rights advocates says the lower house of the Wisconsin Legislature, the State Assembly, was gerrymandered by its Republican majority before the 2012 election — so artfully, in fact, that Democrats won a third fewer Assembly seats than Republicans despite prevailing in the popular vote. In November, in a 2-to-1 ruling, a panel of federal judges agreed.

Now the Wisconsin case is headed to a Supreme Court that has repeatedly said that extreme partisan gerrymanders are unconstitutional, but has never found a way to decide which ones cross the line.

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The Wisconsin plaintiffs’ attempt to break the logjam is a new standard, the efficiency gap. It is a numerical rating of parties’ “wasted” votes: those above the 50-percent-plus-1 needed to win a seat, and all votes cast in a loss. When the gap between the parties’ ratings exceeds a limit based on ratings from hundreds of past elections, the plaintiffs argue, the majority party should have to justify the boundaries it drew. Even then, plaintiffs would have to prove the party aimed to weaken the opposition.

The Wisconsin case underscores how modern gerrymanders, using computers and political and behavioral data, have become increasingly effective. Measured by the efficiency gap, four of the five most partisan state legislature maps in the last 45 years were drawn after 2010, said Nicholas O. Stephanopoulos, a University of Chicago law professor and lawyer for the plaintiffs.