Have we solved partisan gerrymandering?

In a 2004 case called Vieth v Jubelirer, Supreme Court Justice Anthony Kennedy — as usual, the swing vote — said that he didn’t see a workable solution for the problem of partisan gerrymandering. He therefore voted with the conservatives on the Court to rule that the whole matter was a “non-justiciable political question,” a fancy way for the Court to say, “Don’t ask us.”

But Kennedy, ever possessed of a lofty imagination, allowed for the possibility that some clever lawyer somewhere might someday devise what had up until 2004 eluded us: an intelligent and user-friendly formula for determining when partisan gerrymandering has gone too far.

Has that day arrived?

In a case (Gill v Whitford) just heard by the Court, lawyers challenging Wisconsin’s Republican-gerrymandered election map have proposed a solution: the “efficiency gap.” Here’s how it works.

Imagine that the State of Oz has 5 election districts. The state is evenly divided — 250 Republicans live in Oz, as do 250 Democrats. But Republicans, having wrested control of the legislature in Oz, seek to redraw the election districts so that Republicans might maintain a durable and acute advantage for years to come.

The way to do that would be to pack as many Democrats as possible into as few districts as possible, creating a map that might look contorted and goofy, but achieves the goal of clumping lefties into concentrated geographical clusters. Republicans might decide that they want 4 districts out of the 5 with safe Republican majorities (let’s say a 55-45 advantage) and that they’ll sacrifice one district and pack all the Democrats they can into that one district. It would look like this:


Under this scenario, Republicans would likely win Districts 1 through 4 by 55-45 margins and sacrifice District 5 in a 70-30 Democratic landslide: 4 relatively safe districts and one throw-away. That would be good for control of 80% of the legislative seats in Oz, a state that is divided 50-50.

Assume an election where everyone voted predictably — Republicans for Republicans and Democrats for Democrats. The efficiency gap proposed in the Gill case would measure “wasted votes” to determine whether the state was intolerably politically gerrymandered. In District 1, for example, Republicans would have wasted 9 votes. That’s because they only needed 46 votes to win, but built in an extra 9 for a safe cushion. Democrats wasted 45 votes in District 1 because all those votes were cast in a district Democrats were very unlikely to win — in a losing effort. The same goes for Districts 2, 3, and 4: in each, Republicans wasted 9 votes and Democrats wasted 45.

In District 5, Republicans wasted 30 votes in a losing effort. But they still wasted fewer votes than Democrats, who only needed 31 votes to win, but wasted another 39 votes achieving a 70-vote wipe-out.


All in all, Democrats “wasted” 219 votes while Republicans wasted 67. Since there were 250 voters in each party statewide, that means Democrats wasted 88% of their votes while Republicans only wasted 27% of theirs.

In raw numbers, Democrats wasted 152 more votes than Republicans. The efficiency gap is calculated simply by dividing that number — 152 — by the total number of votes cast: 500.  So the efficiency gap in Oz is just over 30% (152/500 = .304).

According to Nicholas Stephanopoulos, the scholar who proposed this methodology, any gap over 7% exceeds the historical norms in US elections and is evidence of improper gerrymandering.

Will Kennedy find this a workable standard? Stay tuned.