'In June, the Supreme Court agreed to hear its first partisan gerrymandering case in more than a decade. This case, Gill v. Whitford, involves a challenge to the district plan that Wisconsin passed for its state house after the 2010 Census. The case also involves a quantitative measure of gerrymandering — the efficiency gap, . . . a simple and intuitive measure of gerrymandering. But the true breakthrough in Whitford isn’t that plaintiffs have finally managed to quantify gerrymandering. Rather, it’s that they’ve used the efficiency gap (and other metrics) to analyze the Wisconsin plan in new and powerful ways.'