Partisan gerrymandering is an offense to democracy. It creates districts that are skewed and uncompetitive, denying voters the ability to elect representatives who fairly reflect their views. But on Tuesday, the Supreme Court will hear a case in which a small dose of math can help the justices root out these offenses more easily. Redistricting may seem unglamorous, but it comes up repeatedly before the court. Last month, the justices heard a case that could streamline the path by which they receive such complaints. In oral arguments, Chief Justice John G. Roberts Jr. expressed his fear that his court could be flooded with complex redistricting cases. But he needn’t be concerned. Tuesday’s case gives the court a chance to adopt a simple statistical standard for fairness that cuts through the legal morass. In the United States legislative system, district maps must be redrawn every 10 years, after each census, a process that legislators manipulate to gain advantage.
Partisan redistricters stuff voters of the opposing party into a smaller number of districts, while spreading their own voters over a larger number of districts to eke out as many bare wins as possible. It is possible for a party to win more than half of the popular vote in a state, yet control fewer than one-third of the legislative seats. This is not a theoretical problem: Precisely such a thing happened in 2012 with the congressional delegations of Pennsylvania and North Carolina.
Litigants often scrutinize individual districts, even though the law allows districts to assume odd shapes. A district map may, however, be rejected if it shows partisan asymmetry — undue favor to one side or the other. Identifying such asymmetry requires examining all the districts in the state.
This is a job for statistics. An easy test is available that directly measures overall bias: the difference between the average and the median. Thiscentury-old statistic uses math that is in the Common Core standards for sixth grade. It also won this year’s competition for a gerrymandering standard sponsored by the nonpartisan organization Common Cause.
Full Article: Let Math Save Our Democracy – The New York Times.