Over the last few years, there has been an unprecedented outpouring of scholarship on partisan gerrymandering. Much of this work has sought either to introduce new measures of gerrymandering or to analyze a metric—the efficiency gap— that we previously developed. In this Essay, we reframe the debate by presenting a series of criteria that can be used to evaluate gerrymandering metrics: (1) consistency with the efficiency principle; (2) distinctness from other electoral values; (3) breadth of scope; and (4) correspondence with U.S. electoral history. We then apply these criteria to both the efficiency gap and other measures. The efficiency gap complies with our criteria under all circumstances. Other metrics, in contrast, often violate the efficiency principle and cannot be used in certain electoral settings.

* Nicholas O. Stephanopoulos is a Professor of Law and Herbert and Marjorie Fried Research Scholar at the University of Chicago Law School. Eric M. McGhee is a Research Fellow at the Public Policy Institute of California.