Partisan Gerrymandering and the Efficiency Gap Nicholas Stephanopoulos
Total Page:16
File Type:pdf, Size:1020Kb
University of Chicago Law School Chicago Unbound Public Law and Legal Theory Working Papers Working Papers 2014 Partisan Gerrymandering and the Efficiency Gap Nicholas Stephanopoulos Eric McGhee Follow this and additional works at: https://chicagounbound.uchicago.edu/ public_law_and_legal_theory Part of the Law Commons Chicago Unbound includes both works in progress and final versions of articles. Please be aware that a more recent version of this article may be available on Chicago Unbound, SSRN or elsewhere. Recommended Citation Nicholas Stephanopoulos & Eric McGhee, "Partisan Gerrymandering and the Efficiency Gap" (Public Law and Legal Theory Working Paper No. 493, 2014) available at http://ssrn.com/abstract=2457468.. This Working Paper is brought to you for free and open access by the Working Papers at Chicago Unbound. It has been accepted for inclusion in Public Law and Legal Theory Working Papers by an authorized administrator of Chicago Unbound. For more information, please contact [email protected]. CHICAGO PUBLIC LAW AND LEGAL THEORY WORKING PAPER NO. 493 PARTISAN GERRYMANDERING AND THE EFFICIENCY GAP Nicholas Stephanopoulos and Eric McGhee THE LAW SCHOOL THE UNIVERSITY OF CHICAGO October 2014 This paper can be downloaded without charge at the Public Law and Legal Theory Working Paper Series: http://www.law.uchicago.edu/academics/publiclaw/index.html and The Social Science Research Network Electronic Paper Collection. PARTISAN GERRYMANDERING AND THE EFFICIENCY GAP 82 U. CHI. L. REV. (forthcoming 2015) Nicholas O. Stephanopoulos* Eric M. McGhee** The usual legal story about partisan gerrymandering is relentlessly pessimistic. The courts did not even recognize the cause of action until the 1980s; they have never struck down a district plan on this basis; and four sitting Justices want to vacate the field altogether. The Supreme Court’s most recent gerrymandering decision, however, is the most encouraging development in this area in a generation. Several Justices expressed interest in the concept of partisan symmetry—the idea that a plan should treat the major parties symmetrically in terms of the conversion of votes to seats—and suggested that it could be shaped into a legal test. In this Article, we take the Justices at their word. First, we introduce a new measure of partisan symmetry: the efficiency gap. It represents the difference between the parties’ respective wasted votes in an election, divided by the total number of votes cast. It captures, in a single tidy number, all of the packing and cracking decisions that go into a district plan. It also is superior to the metric of gerrymandering, partisan bias, that litigants and scholars have used until now. Partisan bias can be calculated only by shifting votes to simulate a hypothetical tied election. The efficiency gap eliminates the need for such counterfactual analysis. Second, we compute the efficiency gap for congressional and state house plans between 1972 and 2012. Over this period as a whole, the typical plan was fairly balanced and neither party enjoyed a systematic advantage. But in recent years—and peaking in the 2012 election—plans have exhibited steadily larger and more pro-Republican gaps. In fact, the plans in effect today are the most extreme gerrymanders in modern history. And what is more, several likely will remain extreme for the remainder of the decade, as indicated by our sensitivity testing. Finally, we explain how the efficiency gap could be converted into doctrine. We propose setting thresholds above which plans would be presumptively unconstitutional: two seats for congressional plans and eight percent for state house plans, but only if the plans probably will stay unbalanced for the rest of the * Assistant Professor of Law, University of Chicago Law School. ** Research Fellow, Public Policy Institute of California. This Article builds on our earlier legal and political science work on redistricting. It is part of a larger project aimed at grasping the consequences—and improving the law—of this important and intricate activity. For helpful comments, we are grateful to Bruce Cain, Jowei Chen, Chris Elmendorf, Andrew Gelman, Michael Gilbert, Ruth Greenwood, Bernie Grofman, Rick Hasen, Benjamin Highton, Vlad Kogan, Justin Levitt, and Rick Pildes. We are pleased as well to acknowledge the support of the Robert Helman Law and Public Policy Fund at the University of Chicago. Electronic copy available at: http://ssrn.com/abstract=2457468 1 Efficiency Gap cycle. Plans with gaps above these thresholds would be unlawful unless states could show that the gaps either resulted from the consistent application of legitimate policies, or were inevitable due to the states’ political geography. This approach would neatly slice the Gordian knot the Court has tied for itself, explicitly replying to the Court’s “unanswerable question” of “how much political . effect is too much.” TABLE OF CONTENTS INTRODUCTION .............................................................................................1 I. THE DOCTRINAL OPPORTUNITY ...................................................................... 6 A. Pre-LULAC ................................................................................................ 6 B. LULAC ...................................................................................................... 8 C. Post-LULAC ............................................................................................ 11 II. THE EFFICIENCY GAP ..................................................................................... 14 A. Definition and Computation .................................................................... 14 B. Key Properties ......................................................................................... 16 C. Comparison to Partisan Bias ................................................................... 18 D. Limitations .............................................................................................. 25 III. GERRYMANDERING OVER TIME AND SPACE .................................................. 28 A. Summary Statistics .................................................................................. 29 B. Individual Plans ....................................................................................... 34 C. Gerrymandering Litigation ...................................................................... 36 IV. A POTENTIAL TEST ........................................................................................ 39 A. Setting the Threshold............................................................................... 40 B. Presumptive Validity and Invalidity ........................................................ 44 C. Concerns and Responses ......................................................................... 48 CONCLUSION ........................................................................................................ 51 INTRODUCTION Cass Sunstein once quipped that the non-delegation doctrine (which purports to limit congressional delegations of authority to agencies) “has had one good year, and 211 bad ones.”1 According to the conventional wisdom, the cause of action for partisan gerrymandering2 has not had even this one good year. The claim was not recognized until 1986, when the Supreme Court ruled that gerrymandering is justiciable but still upheld a pair of Indiana district plans that used every trick in the book to disadvantage the state’s Democrats.3 Since 1986, not a single plaintiff has managed to persuade a court to strike down a plan on 1 Cass R. Sunstein, Nondelegation Canons, 67 U. CHI. L. REV. 315, 322 (2000). 2 We note at the outset that, consistent with the metric we introduce in this Article, whenever we refer to “gerrymandering,” we mean district plans whose electoral consequences are asymmetric. We do not mean plans that were devised with partisan intent. Our conception of gerrymandering is strictly effects-based. 3 See Davis v. Bandemer, 478 U.S. 109, 118-43 (1986). Electronic copy available at: http://ssrn.com/abstract=2457468 Efficiency Gap 2 this basis.4 By our count, claimants’ record over this generation-long period is roughly zero wins and fifty losses.5 And adding insult to injury, a majority of the Court rejected almost every conceivable test for gerrymandering in 2004, and a plurality would have extricated the judiciary from this domain altogether.6 But the gloomy conventional wisdom is not quite right. In the Court’s most recent gerrymandering case, LULAC v. Perry,7 several Justices expressed surprising enthusiasm for the concept of partisan symmetry—the idea, that is, that a district plan should treat the major parties symmetrically with respect to the conversion of votes to seats. Justice Stevens raved that symmetry is “widely accepted by scholars as providing a measure of partisan fairness in electoral systems.”8 Justice Souter noted that “[i]nterest in exploring this notion is evident.”9 And, most remarkably of all, Justice Kennedy declared that he did not “discount[] its utility in redistricting planning and litigation.”10 These comments, overlooked by almost all scholars and litigants in the aftermath of LULAC,11 are the most promising development in this area in decades. They provide the motivation for our effort, in this Article, to introduce a new measure of partisan symmetry and to show how it could be fashioned into a workable judicial standard. We dub our new measure the efficiency gap.12 It represents the difference between