Michael McDonald has written this article for the Yale Law Journal Forum. Here is the abstract:
Scholars have proposed more than one hundred measures of district compactness to analyze legislative maps, but each of these measures lacks a critical threshold at which a district becomes suspect. To address this deficiency, this Essay proposes an analytical framework, the “Predominance Test,” that compares district compactness in a given legislative map against a near-maximally compact redistricting plan. The test has three virtues: (1) it provides a judicially manageable standard to identify when a compactness violation occurs, in a legal framework familiar to courts; (2) it can be used with any compactness measure; and (3) it evaluates compactness with respect to what is possible in a district’s geographic region. This Essay describes an application of the Predominance Test in a challenge to Virginia’s state legislative districts, where a judge accepted the test and found the evidence it produced compelling. While the Predominance Test is not a cure for gerrymandering, it can help constrain the most egregious gerrymanders.