Amicus Curiae Brief — Robert A. Rucho, et al., Appellants v. Common Cause, et al.

Nos. 18-422, 18-726

IN THE

Supreme Court of the United States

_______________________________

ROBERT A. RUCHO, ET AL.,

v.

COMMON CAUSE, ET AL.,

_______________________________

Appellants,

Appellees.

ON APPEAL FROM THE UNITED STATES

DISTRICT COURT FOR THE

MIDDLE DISTRICT OF NORTH CAROLINA

_______________________________

LINDA H. LAMONE, ET AL.,

v.

O. JOHN BENISEK, ET AL.,

_______________________________

Appellants,

Appellees.

ON APPEAL FROM THE UNITED STATES

DISTRICT COURT FOR THE DISTRICT OF MARYLAND

_______________________________

BRIEF OF BERNARD GROFMAN AND RONALD

KEITH GADDIE AS AMICI CURIAE

IN SUPPORT OF NEITHER PARTY

_______________________________

Thomas M. Bondy

Hannah Garden-Monheit

Elizabeth R. Cruikshank

ORRICK, HERRINGTON &

SUTCLIFFE LLP

1152 15th Street, NW

Washington, DC 20005

E. Joshua Rosenkranz

Counsel of Record

ORRICK, HERRINGTON &

SUTCLIFFE LLP

51 West 52nd Street

New York, NY 10019

(212) 506-5000

jrosenkranz@orrick.com

Counsel for Amici Curiae

i

TABLE OF CONTENTS

Page

TABLE OF AUTHORITIES ..................................... ii

INTEREST OF AMICI CURIAE .............................. 1

INTRODUCTION AND SUMMARY OF

ARGUMENT ....................................................... 4

ARGUMENT ............................................................. 6

I.

Courts Must Provide a Check on

Egregious Partisan Gerrymandering. ............... 6

II. Partisan Gerrymanders Can Be Identified

and Measured on a Single-District Basis. ....... 11

A. Courts can readily identify packing or

cracking in a specific district that costs

the party out of power at least one

seat............................................................... 12

B. Testing for responsiveness can

establish whether packing or cracking

will persistently deprive opposition

voters of a seat............................................. 15

C. Computer simulations can establish

whether the partisan disparity in the

challenged district was caused by

invidious discrimination rather than

neutral factors or chance. ........................... 18

CONCLUSION ........................................................ 26

ii

TABLE OF AUTHORITIES

Page(s)

Cases

Abrams v. Johnson,

521 U.S. 74 (1997) ..................................................3

Ariz. State Legislature v. Ariz. Indep.

Redistricting Comm’n,

135 S. Ct. 2652 (2015)......................................3, 10

Badham v. Eu,

694 F. Supp. 664 (N.D. Cal. 1988).........................3

Bartlett v. Strickland,

556 U.S. 1 (2009) ..................................................12

Bush v. Vera,

517 U.S. 952 (1996) ................................................3

Common Cause v. Rucho,

279 F. Supp. 3d 587 (M.D.N.C. 2018) .................25

Cooper v. Harris,

137 S. Ct. 1455 (2017)............................................8

Cox v. Larios,

542 U.S. 947 (2004) ................................................4

Davis v. Bandemer,

478 U.S. 109 (1986) .................................. 3, 6, 9, 17

Georgia v. Ashcroft,

539 U.S. 461 (2003) ..........................................3, 12

iii

Gill v. Whitford,

138 S. Ct. 1916 (2018).............................. 3, 4, 7, 11

Growe v. Emison,

507 U.S. 25 (1993) ................................................14

Holder v. Hall,

512 U.S. 874 (1994) ................................................3

Johnson v. De Grandy,

512 U.S. 997 (1994) ................................................3

League of United Latin American

Citizens v. Perry,

548 U.S. 399 (2006) ............................................3, 4

League of Women Voters v.

Commonwealth of Pennsylvania,

178 A.3d 737 (Pa. 2018) ........................... 21, 23, 26

Miller v. Johnson,

515 U.S. 900 (1995) ..........................................3, 25

Raleigh Wake Citizens Ass’n v. Wake

Cty. Bd. of Elections,

827 F.3d 333 (4th Cir. 2016)................................22

Reynolds v. Sims,

377 U.S. 533 (1964) ................................................8

Shaw v. Hunt,

517 U.S. 899 (1996) ................................................3

Shaw v. Reno,

509 U.S. 630 (1993) ......................................3, 4, 25

iv

Shelby Cty. v. Holder,

570 U.S. 529 (2013) ................................................3

Thornburg v. Gingles,

478 U.S. 30 (1986) ...................................... 3, 12, 13

Vieth v. Jubelirer,

541 U.S. 267 (2004) .................................... 3, 19, 20

White v. Register,

412 U.S. 755 (1973) ..............................................26

Other Authorities

Br. of Political Geography Scholars, Gill

v. Whitford, No. 16-1161 (U.S. 2017) ..................21

Charles S. Bullock, III & Ronald Keith

Gaddie, The Triumph of Voting

Rights in the South (2009) ......................... 2, 19, 20

Charles S. Bullock, III, Ronald Keith

Gaddie & Justin J. Wert, The Rise

and Fall of the Voting Rights Act

(2016) ......................................................................2

Jowei Chen & Jonathan Rodden,

Cutting Through the Thicket:

Redistricting Simulations and the

Detection of Partisan Gerrymanders,

14 Election L.J. 312 (2015) ..................................22

v

Wendy Tam Cho et al., A Reasonable

Bias Approach to Gerrymandering:

Using Automated Plan Generation to

Evaluate Redistricting Proposals, 59

William & Mary L. Rev. 1521 (2018) ..................22

Ronald Keith Gaddie & Charles S.

Bullock, III, Elections to Open

Seats in the U.S. House: Where the

Action Is (2000) ......................................................2

Ronald Keith Gaddie & Charles S.

Bullock, III, From Ashcroft To

Larios: Recent Redistricting Lessons

from Georgia, 34 Fordham Urb.

L.J. 997 (2007) .......................................................2

Bernard Grofman, Criteria for

Districting: A Social Science

Perspective, 33 UCLA L. Rev. 77

(1985) ................................................................6, 19

Bernard Grofman, Measures of Bias

and Proportionality in Seats-Votes

Relationships, 9 Pol. Methodology

295 (1983) ...............................................................1

Bernard Grofman, Tests for

Unconstitutional Partisan

Gerrymandering in a Post-Gill

World, 18 Election L.J.

(forthcoming 2019) ...............................................12

vi

Bernard Grofman & Thomas L. Brunell,

The Art of the Dummymander: The

Impact of Recent Redistrictings on

the Partisan Makeup of Southern

House Seats, in Redistricting in the

New Millennium (Peter Galderisi

ed., 2005) ..............................................................17

Bernard Grofman & Jonathan R.

Cervas, Can State Courts Cure

Partisan Gerrymandering: Lessons

from League of Women Voters v.

Commonwealth of Pennsylvania

(2018), 17 Election L.J. 264 (2018)........................1

Bernard Grofman & Gary King, The

Future of Partisan Symmetry as a

Judicial Test for Partisan

Gerrymandering after LULAC v.

Perry, 6 Election L.J. 2 (2007).........................1, 17

Bernard Grofman, William Koetzle &

Thomas Brunell, An Integrated

Perspective on the Three Potential

Sources of Partisan Bias:

Malapportionment, Turnout

Differences, and the Geographic

Distribution of Party Vote Shares, 16

Electoral Stud. 457 (1997) .....................................1

vii

Bernard Grofman, Michael Migalski &

Nicholas Noviello, The “Totality of

Circumstances Test” in Section 2 of

the 1982 Extension of the Voting

Rights Act: A Social Science

Perspective, 7 L. & Pol’y 199 (1985) ......................1

Justin Levitt, Where Are The Lines

Drawn?, All About Redistricting,

https://tinyurl.com/aw3qgn5 (last

visited Feb. 5, 2019) .............................................19

Jonathan Mattingly et al., Quantifying

Gerrymandering,

https://tinyurl.com/yc4cvxkg (last

visited Feb. 5, 2019) .............................................22

Michael D. McDonald & Robin E. Best,

Unfair Partisan Gerrymanders in

Politics and Law: A Diagnostic

Applied to Six Cases, 14 Election

L.J. 312 (2015) ...............................................16, 19

Anthony J. McGann et al.,

Gerrymandering in America (2016) .... 9, 10, 17, 20

Richard G. Niemi, Bernard Grofman,

Carl Carlucci & Thomas Hofeller,

Measuring Compactness and the

Role of a Compactness Standard

in a Test for Partisan and Racial

Gerrymandering, 52 J. of Pol.

1155 (1990) .............................................................1

viii

Guillermo Owen & Bernard Grofman,

Optimal Partisan Gerrymandering,

7 Pol. Geography Q. 5 (1988) .................................1

Olga Pierce, Jess Larson & Lois

Beckett, Redistricting, A Devil’s

Dictionary, ProPublica (Nov. 2,

2011), https://tinyurl.com/y9uuagw8 ....................6

Report of the Special Master, ECF No.

323, Bethune-Hill v. Va. State Bd. of

Elections, No. 14-CV-0852 (E.D. Va.

Dec. 7, 2018) ...........................................................7

State Partisan Composition, Nat’l

Conference of State Legislatures,

https://tinyurl.com/guos34u (last

updated Feb. 4, 2019) ..........................................10

Nicholas O. Stephanopoulos, Race,

Place, and Power, 68 Stan. L. Rev.

1323 (2016) ...........................................................14

Nicholas O. Stephanopoulos & Eric M.

McGhee, Partisan Gerrymandering

and the Efficiency Gap, 82 U. Chi. L.

Rev. 831 (2015) ....................................................16

Samuel S. H. Wang, Three Practical

Tests for Gerrymandering:

Application to Maryland and

Wisconsin, 16 Election L.J. 367

(2016) ....................................................................18

1

INTEREST OF AMICI CURIAE 1

Amici are political scientists who specialize in redistricting, including the statistical methods used to

detect and measure partisan gerrymandering. Amici

have served as expert witnesses and consultants in

redistricting cases on behalf of both states and plaintiffs, Republicans and Democrats. They have also

published many peer-reviewed articles on the subject. 2

1 The parties have consented to the filing of this amicus

brief. No counsel for a party authored the brief in whole or in

part. No party, counsel for a party, or any person other than

amici curiae and their counsel made a monetary contribution intended to fund the preparation or submission of the brief.

2

Professor Grofman’s publications include Bernard

Grofman & Jonathan R. Cervas, Can State Courts Cure Partisan

Gerrymandering: Lessons from League of Women Voters v.

Commonwealth of Pennsylvania (2018), 17 Election L.J. 264

(2018); Bernard Grofman & Gary King, The Future of Partisan

Symmetry as a Judicial Test for Partisan Gerrymandering after

LULAC v. Perry, 6 Election L.J. 2 (2007); Bernard Grofman,

William Koetzle & Thomas Brunell, An Integrated Perspective on

the Three Potential Sources of Partisan Bias: Malapportionment,

Turnout Differences, and the Geographic Distribution of Party

Vote Shares, 16 Electoral Stud. 457 (1997); Richard G. Niemi,

Bernard Grofman, Carl Carlucci & Thomas Hofeller, Measuring

Compactness and the Role of a Compactness Standard in a Test

for Partisan and Racial Gerrymandering, 52 J. of Pol. 1155

(1990); Guillermo Owen & Bernard Grofman, Optimal Partisan

Gerrymandering, 7 Pol. Geography Q. 5 (1988); Bernard

Grofman, Michael Migalski & Nicholas Noviello, The “Totality of

Circumstances Test” in Section 2 of the 1982 Extension of the

Voting Rights Act: A Social Science Perspective, 7 L. & Pol’y 199

(1985); Bernard Grofman, Measures of Bias and Proportionality

in Seats-Votes Relationships, 9 Pol. Methodology 295 (1983).

2

Amici seek to assist the Court in understanding

recent developments in social science methodologies

for identifying and measuring the extent of partisan

gerrymanders. They do not take a position on

whether, given the particular facts and expert witness analyses, the district courts correctly decided

these cases. But amici firmly believe that partisan

gerrymanders are justiciable, and that this Court

should adopt an articulable standard for adjudicating

partisan gerrymandering claims. Social science tools

now allow courts to diagnose partisan gerrymanders

with accuracy and precision, including identifying the

specific legislative district or districts affected. They

also allow courts to distinguish ordinary, acceptable

politicking from conduct that rises to the level of unconstitutional discrimination against voters based on

their political views. If the Court again declines to

adopt a standard for unconstitutional partisan gerrymandering, politicians will have free rein to violate

associational and representational rights.

Amicus Bernard Grofman is the Jack W. Peltason

Chair of Democracy Studies and Distinguished Professor of Political Science at the University of California, Irvine. He has frequently served as an expert

Professor Gaddie’s publications include Charles S. Bullock,

III, Ronald Keith Gaddie & Justin J. Wert, The Rise and Fall of

the Voting Rights Act (2016); Charles S. Bullock, III & Ronald

Keith Gaddie, The Triumph of Voting Rights in the South (2009);

Ronald Keith Gaddie & Charles S. Bullock, III, From Ashcroft

To Larios: Recent Redistricting Lessons from Georgia, 34

Fordham Urb. L.J. 997 (2007); Ronald Keith Gaddie & Charles

S. Bullock, III, Elections to Open Seats in the U.S. House: Where

the Action Is (2000).

3

witness and consultant in redistricting cases, including for the State of Indiana in Davis v. Bandemer, 478

U.S. 109 (1986), and for the plaintiffs in Thornburg v.

Gingles, 478 U.S. 30 (1986), and Badham v. Eu, 694

F. Supp. 664 (N.D. Cal. 1988), aff’d, 488 U.S. 1024

(1989). He joined amicus briefs on behalf of neither

party in Gill v. Whitford, 138 S. Ct. 1916 (2018), Vieth

v. Jubelirer, 541 U.S. 267 (2004), and League of

United Latin American Citizens (LULAC) v. Perry,

548 U.S. 399 (2006), urging that partisan gerrymanders are justiciable. This Court has previously cited

Professor Grofman’s work (including volumes he edited) in over a dozen cases. 3 Scholars often credit his

brief in LULAC with introducing the Court to the first

generation of social science analysis of partisan asymmetry, and his work was cited extensively in the development of the Gingles test for evaluating racial

vote dilution under the Voting Rights Act. Professor

Grofman has also drawn redistricting plans for federal district courts, non-partisan commissions, and

the U.S. Department of Justice—including recent service in 2015 as the special master to a federal district

court after it declared Virginia’s Congressional District 3 unconstitutional; in 2017 as the special master

to a district court responsible for the redrawing of

3 See Ariz. State Legislature v. Ariz. Indep. Redistricting

Comm’n, 135 S. Ct. 2652 (2015); Shelby Cty. v. Holder, 570 U.S.

529 (2013); LULAC v. Perry, 548 U.S. 399 (2006); Vieth v. Jubelirer, 541 U.S. 267 (2004); Georgia v. Ashcroft, 539 U.S. 461

(2003); Abrams v. Johnson, 521 U.S. 74 (1997); Shaw v. Hunt,

517 U.S. 899 (1996); Bush v. Vera, 517 U.S. 952 (1996); Miller v.

Johnson, 515 U.S. 900 (1995); Johnson v. De Grandy, 512 U.S.

997 (1994); Holder v. Hall, 512 U.S. 874 (1994); Shaw v. Reno,

509 U.S. 630 (1993); Thornburg v. Gingles, 478 U.S. 30 (1986);

Davis v. Bandemer, 478 U.S. 109 (1986).

4

county commission and school district lines in a small

Utah County with a large Navajo population after the

previous maps were found unconstitutional under

Shaw v. Reno; and in 2018 as the special master to a

district court responsible for the redrawing of eleven

Virginia legislative districts found to be unconstitutional under Shaw. Professor Grofman’s curriculum

vitae is available at https://tinyurl.com/y8ppxmvg.

Amicus Ronald Keith Gaddie is the President’s

Associates Presidential Professor of Political Science,

Architecture and Journalism at the University of Oklahoma and an editor of Social Science Quarterly. He

too has served as an expert witness and consultant in

numerous redistricting cases, including for the State

of Texas in LULAC and for the plaintiffs in Cox v. Larios, 542 U.S. 947 (2004). Most recently, Professor Gaddie worked as a consultant to the Wisconsin

legislature’s Republican leadership in drafting the

map at issue in Gill v. Whitford; the Republican Caucus’s attorneys hired Professor Gaddie to assess,

among other things, the expected partisan impact of

the proposed maps. Professor Gaddie has always believed that partisan gerrymanders are justiciable. He

coauthored an amicus brief with Professor Grofman

in Gill. His curriculum vitae is available at https://tinyurl.com/y874ysrm.

INTRODUCTION AND SUMMARY OF

ARGUMENT

Modern, computer-driven redistricting now allows the political party in power to craft extremely sophisticated partisan gerrymanders. With vastly

improved computer speed, memory, and storage, map

5

drawers can design district lines so precisely that

they simultaneously maximize their party’s gains and

eliminate most competitive districts—ensuring that

the party in power enjoys an electoral advantage that

endures throughout the following decade, irrespective

of voters’ subsequent choices.

Left unchecked, partisan gerrymandering fundamentally undermines our democracy. It is a basic

tenet of fair elections that the parties must play by

the same rules. But a partisan gerrymander violates

that core principle: Under a successful partisan gerrymander, one party needs fewer votes to win representation than the other party. A partisan

gerrymander dilutes the votes of some members of the

electorate, simply because of their partisan affiliation. And where the partisan gerrymander is unresponsive to electoral shifts, only the courts can

provide a remedy.

This Court should hold that partisan gerrymandering claims are justiciable. To be precise, partisan

gerrymandering occurs when a districting plan subjects voters to unequal treatment in the weight of

their votes, diluting the power of disfavored citizens’

votes compared to what might be expected from a plan

drawn on the basis of neutral principles. But not all

partisan gerrymanders are unconstitutional. The

Court should adopt a test for unconstitutional partisan gerrymandering that requires a showing of packing or cracking in a particular district or set of

districts that is caused by invidious discrimination

and persistently costs the party out of power at least

one seat. The district-specific standard we propose

provides a judicially manageable framework through

6

which judges can and should identify and evaluate

the extent of partisan gerrymanders. And social science provides ample tools—in the form of analytical

tests and computer simulations—to assist the judiciary in conducting those inquiries.

ARGUMENT

I.

Courts Must Provide a Check on Egregious

Partisan Gerrymandering.

Invidious partisan gerrymandering occurs when a

political party intentionally redraws legislative district lines to give itself a durable electoral advantage

over the party out of power, penalizing disfavored voters and diluting their votes. 4 The two indispensable

tools of partisan gerrymandering are “packing” and

“cracking.” See, e.g., Davis v. Bandemer, 478 U.S. 109,

117 n.6 (1986) (describing “familiar techniques of political gerrymandering”). 5 “Cracking” means spreading opposition party voters across multiple districts so

4 We use the phrase “dominant party” to refer to the party

doing the line drawing, even if it is not a voting majority of the

electorate. The phrase “opposition party” refers to the party out

of power.

Other partisan gerrymandering techniques maximize

partisan advantage by treating the disfavored party’s

incumbents disparately, through pairing two incumbents of the

disfavored party in one district to preclude one’s reelection

(“hijacking”) or separating an opposition party incumbent from

her core supporters to reduce her chances of reelection

(“kidnapping”). See Olga Pierce, Jess Larson & Lois Beckett,

Redistricting, A Devil’s Dictionary, ProPublica (Nov. 2, 2011),

https://tinyurl.com/y9uuagw8; see generally Bernard Grofman,

Criteria for Districting: A Social Science Perspective, 33 UCLA

L. Rev. 77, 151 (1985). Also belonging in the gerrymandering

5

7

that opposition party support falls short of a majority

in each, rendering the opposition incapable of prevailing in any of those districts. Cracking ensures that

opposition voters within the cracked districts have a

diminished—and vanishingly small—opportunity to

elect their candidates of choice. “Packing,” in turn,

means concentrating the opposition party’s backers

within one or a small number of districts such that

the opposition party wins those districts by overwhelming margins—making those districts essentially noncompetitive. Packing dilutes the influence of

opposition party voters within the packed district,

rendering each such voter functionally irrelevant to

the resulting landslide opposition party victory in the

district, and makes it harder for the opposition to win

seats because of the distribution of its supporters.

Voters who reside in districts that have been

“packed” or “cracked” suffer from having their votes

diluted relative to voters in a non-gerrymandered

baseline district. They have a reduced opportunity for

their vote to make a difference in the outcome of an

election. In short, their votes “carry less weight than

[they] would carry in another, hypothetical district”

that was not gerrymandered. Gill v. Whitford, 138 S.

Ct. 1916, 1931 (2018) (majority op.); see also, e.g.,

lexicon is “fracking,” which Professor Grofman uses to refer to a

form of discontiguity in which a district contains a border that

“traverse[s] a county line more than once.” See Report of the

Special Master, ECF No. 323, at 50-51, Bethune-Hill v. Va. State

Bd. of Elections, No. 14-CV-0852 (E.D. Va. Dec. 7, 2018) (finding

fracking in four Virginia legislative districts identified by the

district court as unconstitutional and no such discontiguity

among districts in the same part of the state whose

constitutionality had not been challenged).

8

Reynolds v. Sims, 377 U.S. 533, 555 (1964) (“[T]he

right of suffrage can be denied by a debasement or dilution of the weight of a citizen’s vote just as effectively as by wholly prohibiting the free exercise of the

franchise.”). This Court has previously held that

packing and cracking injure individual voters who are

subjected to racial gerrymandering by diluting their

votes; vote dilution is also the injury suffered by voters bringing one person, one vote claims. Packing and

cracking similarly dilute the votes of citizens subjected to partisan gerrymandering. 6

Discrimination based on partisanship has realworld consequences. A voter who supports a disfavored party is denied an equal opportunity to use her

vote to affect the representation of her district. Her

vote is diluted relative to favored voters, because she

is “packed” or “cracked” into a district where she does

not affect the outcome. The officials representing her

district are in turn unaccountable to her. Similarly,

across a districting plan, voters from the disfavored

party are denied an equal opportunity to affect the

partisan composition of the legislature—meaning the

legislative proposals they support are less likely to be

introduced, debated, and passed. And because such

voters have been deliberately boxed out of the political process, they may be unable to reverse the dilution

of their votes by electing representatives who will ensure a more neutral distribution of political power. A

6 Although packing does not prevent the election of the

packed voter’s candidate of choice, this Court has recognized

that it nonetheless causes a dilution injury because each packed

individual’s vote has less weight. See, e.g., Cooper v. Harris, 137

S. Ct. 1455 (2017).

9

partisan gerrymander thus discriminates against voters in their representational rights because of their

views and political associations in a way that cannot

realistically be ameliorated through the ordinary electoral process. 7 See Bandemer, 478 U.S. at 124 (“[E]ach

political group in a State should have the same chance

to elect representatives of its choice as any other political group.”).

There is compelling evidence that the 2010 redistricting cycle yielded partisan gerrymandering of a

magnitude that is qualitatively and quantitatively

different from what we have seen in the past—as

much as three times more partisan bias than in the

2000 redistricting cycle—even when controlling for

residential patterns of voters and demographic

change. Anthony J. McGann et al., Gerrymandering

in America 4-5, 97-98 (2016). Indeed, there were

strong increases in bias even where the same party

controlled both the 2000 and 2010 redistricting processes. Id. at 174. This increase in the aggressiveness

of partisan gerrymanders may be driven in part by

the fact that, as a result of the Court’s “signal[] in Vieth v. Jubelirer (2004) that it would not intervene …[,]

state legislatures did not have to worry about the

threat of legal oversight and pushed partisan advantage to its limits” during the 2010 cycle. Id. Absent

7 Plaintiffs alleging unconstitutional partisan gerrymanders have advanced several constitutional theories. Amici have

sought to offer a standard for identifying and evaluating a partisan gerrymander at the district level under the Equal Protection Clause and the First Amendment. But amici also believe

that manageable standards exist for evaluating partisan gerrymanders at a statewide level.

10

a judicial check, the level of egregious partisan gerrymandering may worsen still in 2020 because of a

marked increase in the number of legislatures under

unified partisan control. See State Partisan Composition, Nat’l Conference of State Legislatures, https://tinyurl.com/guos34u (last updated Feb. 4, 2019).

Whether courts should intercede to police egregious partisan gerrymanders is not a matter of one’s

political leanings. While evidence suggests that at a

national level, the net benefits of partisan gerrymandering currently accrue to Republicans, in the past,

the net benefits have accrued to Democrats. McGann

et al., supra, at 71-72, 88. The party in power has

strong incentives to change the map to keep itself

there. Indeed, the Court here is considering a pair of

cases challenging maps enacted by Republicans on

one hand and Democrats on the other. On either side,

where there is improper gerrymandering it is the voters who lose: Their rights are undermined based upon

their political views, and incumbents are entrenched

in office without regard to changes in voter preferences. See Ariz. State Legislature v. Ariz. Indep. Redistricting Comm’n, 135 S. Ct. 2652, 2677 (2015)

(noting “the core principle of republican government”

that “voters should choose their representatives, not

the other way around”).

Courts must serve as a neutral check. If the Court

again declines to adopt a standard for unconstitutional partisan gerrymandering, politicians will have

free rein to wield the technological advances discussed below to craft ever more egregious partisan

gerrymanders. Continued judicial abdication would

ensure that representatives are selected by the self-

11

dealing maps they enact, rather than elected by the

people they ostensibly serve—locking in place electoral advantages that are, for all practical purposes,

impervious to changes by the electorate.

II. Partisan Gerrymanders Can Be Identified

and Measured on a Single-District Basis.

The majority opinion in Gill made clear that the

threshold inquiry under a vote dilution theory of partisan gerrymandering requires identifying specific

districts that have been packed or cracked. See Gill,

138 S. Ct. at 1921 (“The boundaries of the district, and

the composition of its voters, determine whether and

to what extent a particular voter is packed or

cracked.”). In our view, a successful partisan gerrymandering claim will demonstrate packing or cracking in a specific district that is caused by invidious

discrimination and persistently costs the party out of

power at least one seat. Fortunately, while the tests

previously proposed for identifying a partisan gerrymander—including tests that included measures of

partisan asymmetry like the efficiency gap and the

mean-median gap—typically entailed statewide analysis, the Court need not start from scratch to identify

a district-level gerrymander. Instead, the well-developed jurisprudence in racial gerrymandering cases

can be adapted to determine the existence of “packing” or “cracking” in the partisan gerrymandering

context. And existing social science tools can assist

courts in determining the extent to which the challenged district deviates from a neutral baseline,

whether the deviation is likely to persist over election

cycles, and whether invidious partisan discrimination

is the cause.

12

A. Courts can readily identify packing or

cracking in a specific district that costs

the party out of power at least one seat.

The Court’s racial gerrymandering jurisprudence

offers a well-developed framework for identifying

whether a particular district has been packed or

cracked. We propose adapting existing standards to

the partisan gerrymandering context. 8

Racial vote dilution claims under Section 2 of the

Voting Rights Act require a showing that an electoral

measure has resulted in the denial or abridgment of

the right to vote based on race. See Thornburg v. Gingles, 478 U.S. 30, 48-49 (1986); see also Bartlett v.

Strickland, 556 U.S. 1, 26 (2009). 9 In making a

threshold determination of whether the necessary

(but not sufficient) conditions for such a vote dilution

claim have been met, the Court has adopted a threepronged test, in which the plaintiff must prove that

(1) she belongs to a group that is sufficiently large and

geographically compact to constitute a majority in a

single-member district; (2) the group is politically cohesive; and (3) voting is racially polarized, and the

8 Elaboration of some of the tests and measurement issues

discussed in this brief can be found in Bernard Grofman, Tests

for Unconstitutional Partisan Gerrymandering in a Post-Gill

World, 18 Election L.J. (forthcoming 2019) (on file with author).

It will be made available online later this winter.

9 Similarly, under Section 5 of the Voting Rights Act, courts

evaluated whether an electoral change submitted for preclearance would have a retrogressive effect on the ability of minority

voters to elect the candidate of their choice. See, e.g., Georgia v.

Ashcroft, 539 U.S. 461, 480 (2003).

13

level of racial bloc voting is such that in the challenged district the minority candidate usually loses.

See Gingles, 478 U.S. at 48-49. This inquiry can be

readily adapted for application to claims that a district has been unconstitutionally gerrymandered

based on partisanship—that the voter, if not gerrymandered, could be placed in a district in which she

could meaningfully contribute to the election of her

candidate of choice. In adapting this test to partisan

gerrymandering claims, the Court would consider

three factors that parallel the Gingles inquiry—factors that ultimately require partisan gerrymandering

plaintiffs to establish that at least one seat lost to partisan gerrymandering could be gained in a neutral

plan.

The first factor we would propose is whether the

opposition group is sufficiently large and geographically compact in the locality of the challenged district

such that a new district can be drawn in which the

opposition has a majority or in which it has a realistic

opportunity to elect its candidate of choice. 10 Key to

this inquiry is whether the district can be redrawn to

create a majority or opportunity-to-elect district for

the opposition party without reducing the overall

number of districts in which the opposition forms a

10 While districts where the opposition party could form a

majority in a hypothetical non-gerrymandered district present

the most obvious claims, a proper statistical evaluation would be

able to catch even subtler forms of partisan gerrymandering,

such as where several competitive districts have been drawn

with a thumb on the scale so that the number of competitive districts leaning toward the dominant party is greater than the

number of competitive districts drawn leaning toward the opposition party.

14

majority. That is, this factor requires that the opposition party has been deprived of partisan advantage in

at least one district in the enacted plan.

Second, courts should consider whether the opposition group is politically cohesive and voting is polarized along partisan political lines. In the present era

of partisan “hyperpolarization,” demonstrating political cohesiveness will be a much easier task than in

past decades. Indeed, map drawers (legislators and

their staff and consultants) themselves routinely use

historical election data to draw maps. They do so

knowing that past political preferences are highly

predictive of future political fortunes. Courts, assisted

by expert witnesses, can appropriately rely on these

same data to evaluate the partisan consequences of

alternative districting plans. Moreover, experts can

adapt models to account for situations in which past

partisan performance was likely attributable to idiosyncratic factors. In the racial gerrymandering context, courts have long been comfortable relying on

statistical modeling to identify voters’ preferences. Cf.

Growe v. Emison, 507 U.S. 25, 41 (1993). Partisan political modeling is in fact easier in the partisan gerrymandering context than in the racial gerrymandering

context, since in the latter we must model preferences

based on statistical inferences about how racial minorities voted in the past, Nicholas O. Stephanopoulos, Race, Place, and Power, 68 Stan. L. Rev. 1323,

1356 (2016) (describing challenges in drawing ecological inferences about individual preferences from aggregate information), whereas election data tell us

directly how each political party previously performed. And, importantly, modeling voters’ political

15

preferences is not about predicting actual future election outcomes. Rather, modeling establishes how a generic Democrat or Republican would perform—and

thus whether a candidate from one party enters the

playing field with an advantage.

The third factor we propose differs modestly for

packing and cracking claims. For a cracking claim, we

inquire whether opposition candidates in the challenged district regularly lose or, if the plan has not yet

been implemented, whether there is compelling evidence based on past elections that they would be virtually certain to lose. In other words, the test we

propose would find that a challenged district had been

cracked only if opposition voters had been diluted

such that they could not elect their preferred candidate. Meanwhile, for a packing claim, this factor

would inquire whether the challenged district can be

redrawn unpacked to create a district in which the opposition retains its ability to elect a candidate of its

choice that does an equally good or better job of satisfying traditional districting criteria as the challenged

district. In other words, it requires showing that the

packed voters can retain the ability to elect their candidate of choice while being unpacked into another

district that is at least as good at satisfying other,

neutral districting criteria.

B. Testing for responsiveness can establish

whether packing or cracking will

persistently deprive opposition voters of

a seat.

An additional element necessary for the identification of an unconstitutional partisan gerrymander is

16

a lack of responsiveness to the electoral process. Even

if districts are revealed to have been packed or

cracked along partisan lines, if the party out of power

can alter its fate by persuading voters to support it in

the next election, then there is no need for courts to

intervene. In such cases, ordinary politics remain responsive to voters’ preferences; if citizens do not like

policies promulgated by their representatives (including the district maps they enact), they can vote them

out of office. See Michael D. McDonald & Robin E.

Best, Unfair Partisan Gerrymanders in Politics and

Law: A Diagnostic Applied to Six Cases, 14 Election

L.J. 312, 319 (2015) (arguing that the Court “entered

the metaphorical political thicket in the 1960s on the

question of malapportionment” because of “the practical problem … that popular majorities had no political means to correct the offense”); Nicholas O.

Stephanopoulos & Eric M. McGhee, Partisan Gerrymandering and the Efficiency Gap, 82 U. Chi. L. Rev.

831, 865 (2015). In principle, even large-scale disparities in partisan treatment can be fleeting. A constitutional standard for partisan gerrymanders should

accordingly require a separate assessment of electoral

responsiveness, sometimes called “durability.”

Electoral responsiveness describes whether and

how representation changes when voters’ preferences

change. If a map is not responsive, that means that

when voters change their preferences and shift their

allegiances from one party to another, their representation remains unlikely to change—showing that the

politicians have chosen the voters, and not the other

way around. In that circumstance, we can expect citizens’ votes to remain diluted regardless of the outcome of future elections. Conversely, high

17

responsiveness suggests that the discriminatory effect on voters may not be long-lasting.

Measuring responsiveness will also detect “selflimiting” gerrymanders—sometimes called “dummymanders,” see Bernard Grofman & Thomas L. Brunell, The Art of the Dummymander: The Impact of

Recent Redistrictings on the Partisan Makeup of

Southern House Seats, in Redistricting in the New

Millennium 183, 184 (Peter Galderisi ed., 2005)—in

which map drawers crack voters across multiple districts to create margins of victory so thin that they

evaporate in future elections. Bandemer, 478 U.S. at

152 (O’Connor, J., concurring). But dummymanders

can occur only when there are numerous competitive

districts in a map. And there is empirical evidence

that dummymanders are rare. See McGann et al., supra, at 226 (“A second myth we have debunked is that

partisan gerrymandering is self-limiting”). This is increasingly the case as the computer technology for

conducting gerrymanders improves. In any event, assessing responsiveness “allows us to distinguish those

cases in which a gerrymandering might have been attempted but was not very well done from those cases

in which the partisan bias imposed by gerrymandering is expected to be both substantial and long-lasting.” Bernard Grofman & Gary King, The Future of

Partisan Symmetry as a Judicial Test for Partisan

Gerrymandering after LULAC v. Perry, 6 Election

L.J. 2, 13 (2007).

Social science offers tools for evaluating the durability of a gerrymander. Based on historical data—

how much voters’ preferences swung in prior elec-

18

tions—experts can identify the full range of realistically possible election outcomes and determine how

many legislative seats, if any—and, critically, which

seats—would change hands in response to a comparable change in voters’ choices. The number of competitive districts also provides evidence of the map’s

responsiveness. Requiring that plaintiffs demonstrate that a disparate partisan impact will be durable throughout the decade following redistricting—

that the map is not responsive to voters—ensures that

courts do not intervene in the political process when

it is functioning properly. If the map does not persistently obstruct competition, the voters’ remedy lies at

the polls, not in the courts.

C. Computer simulations can establish

whether the partisan disparity in the

challenged district was caused by

invidious discrimination rather than

neutral factors or chance.

1. Once we have identified a district or districts

that have been durably packed or cracked, we know

that a district or districting plan imposes disparate

effects on disfavored voters that are impervious to

electoral tides. But that does not end the inquiry. Rather, there is consensus among social scientists that

to determine whether invidious discrimination is the

cause of a disparate burden on opposition voters, it is

necessary to rule out other potential causes of the district configuration—to assess whether the partisan

effects of a plan are attributable, for example, to neutral principles, voters’ residential patterns, or sheer

random chance. See, e.g., Samuel S. H. Wang, Three

Practical Tests for Gerrymandering: Application to

19

Maryland and Wisconsin, 16 Election L.J. 367, 374

(2016) (“[A] standard for partisan gerrymandering requires a method for determining whether a [claimed

disparity] could have arisen as part of normal variation in districting as practiced across the United

States.”); McDonald & Best, supra, at 317 (“[I]n order

to distinguish unintentional from intentional gerrymanders, a benchmark of what naturally would result

from any neutral line drawing has to be established.”). That is, we must compare the map’s disparate effects against a neutral baseline.

As this Court has noted, advantages to one party

may occur because of a variety of neutral factors. See,

e.g., Vieth v. Jubelirer, 541 U.S. 267, 289-90 (2004)

(plurality op.); id. at 308-09 (Kennedy, J., concurring).

For example, map drawers must comply with the Constitution’s “one person, one vote” and nondiscrimination requirements. They also must comply with the

Voting Rights Act by avoiding racial vote dilution. See

Charles S. Bullock, III & Ronald Keith Gaddie, The

Triumph of Voting Rights in the South 343 (2009).

And many states’ laws also require map drawers to

consider certain traditional districting criteria, like

contiguity, compactness, and preservation of political

subunits like cities and counties, as well as communities of interest—groups of people with a common attribute like race or ethnicity. See, e.g., Justin Levitt,

Where Are The Lines Drawn?, All About Redistricting,

https://tinyurl.com/aw3qgn5 (last visited Feb. 5,

2019) (collecting current, state-by-state requirements

for redistricting); see also Bernard Grofman, Criteria

for Districting: A Social Science Perspective, 33 UCLA

L. Rev. 77 (1985) (Table 3) (collecting state-by-state

requirements for 1980s redistricting).

20

Pursuit of these neutral objectives may produce

inadvertent advantages to one party. For example,

there is some evidence that “political groups that tend

to cluster (as is the case with Democratic voters in cities) [c]ould be systematically affected by what might

be called a ‘natural’ packing effect,” Vieth, 541 U.S. at

290 (plurality op.)—although new empirical evidence

indicates that this effect has been overstated,

McGann et al., supra, at 135 (“[G]eographic and demographic constraints (such as the urban concentration of Democratic voters, the requirement to draw

majority-minority districts, and the geographic sorting of voters) … certainly cannot account for the increase in [partisan] bias we observe between the 2000

and 2010 districting rounds.”). Similarly, compliance

with the Voting Rights Act has spillover effects on a

district’s partisan makeup. See Bullock & Gaddie, supra, at 343. Random chance may also play a role.

Packing or cracking that is merely a side effect of

indisputably legitimate objectives within the redistricting process or that is naturally occurring does not

evidence actionable invidious discrimination. Any

constitutional test for partisan gerrymandering will

thus have to rule out these causes of vote dilution and

isolate the degree of disparate partisan advantage

that is “unrelated to the [legitimate] aims of apportionment,” or to residential patterns or chance. Vieth,

541 U.S. at 313 (Kennedy, J., concurring).

Social science again provides the toolkit: extremely sophisticated and accurate methods of ruling

out neutral factors as the source of partisan asymmetry. Vastly improved computing power permits experts to create hundreds (or even millions) of

21

computer-generated alternative maps. These computer-generated maps are produced to satisfy all traditional districting criteria to at least the same extent

as the challenged plan.

It has become increasingly common in partisan

gerrymandering challenges for experts to offer these

computer-generated simulations of random plans

drawn in accordance with traditional districting principles and reflective of the underlying partisan electoral geography (or, similarly, random permutations

from a challenged map). See, e.g., League of Women

Voters v. Commonwealth of Pennsylvania, 178 A.3d

737, 770-75 (Pa. 2018) (describing the testimony of

Dr. Jowei Chen, centering on computer-generated alternative maps). These simulations serve as a neutral

baseline for comparison with the challenged district.

From these simulations, analysts have used past voting behavior to calculate the range of likely partisan

outcomes resulting from the challenged map or district to evaluate whether a challenged map or district

is a statistical outlier.

This methodology enables us to establish to a high

degree of statistical certainty whether packing or

cracking is explainable by something other than invidious intent. For example, because the alternative

maps take as a given the actual human geography of

the state, any amount of packing that naturally results from residential patterns will be reflected in the

alternative maps, which can also be programmed to

preserve intact communities of interest or districts required by the Voting Rights Act. See, e.g., Br. of Political Geography Scholars, Gill v. Whitford, No. 16-1161

(U.S. 2017), at 7, 12-13 & nn.10-11. These tools enable

22

experts to identify whether disparate effects are

“manmade”—the product of deliberate efforts of the

party in power to penalize the opposition—as distinct

from those that may be produced by the effects of neutral districting priorities, voters’ residential patterns,

or chance. See, e.g., Jowei Chen & Jonathan Rodden,

Cutting Through the Thicket: Redistricting Simulations and the Detection of Partisan Gerrymanders, 14

Election L.J. 312, 312 (2015). We can thus quantify

and rule out any conceivable neutral justification for

packing and cracking.

Political scientists have developed variations on

this computer simulation methodology—with minor

differences in how the random-map-generation algorithm operates, what inputs are used, and how they

are prioritized. E.g., id.; Wendy Tam Cho et al., A Reasonable Bias Approach to Gerrymandering: Using Automated Plan Generation to Evaluate Redistricting

Proposals, 59 William & Mary L. Rev. 1521 (2018);

Jonathan Mattingly et al., Quantifying Gerrymandering, https://tinyurl.com/yc4cvxkg (last visited Feb. 5,

2019). But the basic method is sound, notwithstanding these nuances. Indeed, courts are already relying

on it in the one person, one vote context. See Raleigh

Wake Citizens Ass’n v. Wake Cty. Bd. of Elections, 827

F.3d 333, 344 (4th Cir. 2016) (holding district court

“clearly and reversibly erred in rejecting Dr. Jowei

Chen’s expert testimony,” based on computer generation of 500 randomly drawn redistricting plans, that

a challenged population deviation was the product of

partisan bias). And in a recent state court challenge

to a Pennsylvania redistricting, Professor Chen offered computer simulation evidence about the degree

23

to which the challenged plan failed to satisfy traditional redistricting criteria compared to politically

neutral plans drawn by a computer programmed to

honor traditional districting factors. See League of

Women Voters, 178 A.3d at 770-75. Such evidence can

be relied on as indicative of possible partisan motive.

And as discussed above, even though Professor Chen’s

testimony was about statewide effects, it is straightforward to transform his data into evidence that particular districts are statistical outliers.

While these computer simulations have typically

been produced and evaluated on a statewide basis,

they remain relevant to assessing whether a given

district or set of districts exhibits packing or cracking

to a degree that would be judged as statistically extreme when compared to expectations derived from

maps drawn according to neutral principles. Such an

analysis could be a vital component of a district-specific analysis of partisan gerrymandering, though it

begins with calculations based on statewide data.

This district-level analysis could be applied to either packed or cracked districts. To detect packing,

challenged districts could be ranked in terms of their

actual or expected partisan advantage, with reference

to voter registration data and past voting behavior.

The most heavily opposition district challenged would

be compared against simulation results to evaluate

the extent to which it was more extreme in its partisan composition than the simulation based on neutral

redistricting and whether that difference was statistically significant. The analysis would continue

through the ordered list of districts, evaluating

24

whether the next-most-extreme district in the challenged map was also a statistical outlier with respect

to its concentration of opposition voting strength compared to the neutral baseline, proceeding in this fashion until all the statistical outliers had been

identified; those outlier districts would be candidates

for further evaluation as potentially invidious partisan gerrymanders. A similar approach to allegedly

cracked districts would use information on the most

competitive districts in the computer-generated maps

to ascertain whether districts within the challenged

map exhibited a partisan advantage favoring the majority party to an extent incompatible with neutral

line drawing, in terms of number of districts that were

competitive with an edge toward the dominant party

versus those that were competitive with an edge toward the opposition.

2. We have focused on aiding the Court in understanding the social science tools for isolating the

causes of apparent partisan gerrymanders—a means

of inferring whether a disparate effect on voters was

intentionally imposed. But, of course, nonstatistical

evidence of intent is also relevant. Numerical analyses must be supplemented by more direct inspection

of district boundaries (and how they changed from the

prior map) to establish invidious discrimination. 11

Here, again, a well-developed racial gerrymandering jurisprudence illustrates how the Court can

11 Relatedly, single-party control of the districting process

will likely be a precondition for the finding of an unconstitutional

partisan gerrymander.

25

use nonstatistical evidence to sniff out invidious discrimination on partisan lines. See, e.g., Shaw v. Reno,

509 U.S. 630 (1993). Certainly, public statements by

legislators in the dominant party—perhaps boasting

of their success in doing the best possible partisan

gerrymander—can indicate that an invidious motive

to maximize partisan advantage predominated. 12 So

too can deviations from the ordinary legislative process, such as secrecy, limited debate, or party-line voting in the enactment of the map. And a comparison

between the challenged map and its predecessor may

indicate that the lines were redrawn in a direct and

egregious partisan fashion, as when changes from a

prior plan involved movement of opposition party

strength in or out of districts with no nonpartisan justification proffered. Notably, although discriminatory

partisan gerrymanders may often be visually unremarkable while still maximizing partisan advantage,

contorted district lines and disregard for traditional

districting criteria are surefire signals that partisan

gerrymandering is afoot, even if not themselves illegal. See Miller v. Johnson, 515 U.S. 900, 913 (1995)

12 Many legislators apparently came to believe that there

would be no court-imposed checks on partisan gerrymandering

in the 2010 redistricting round. Accordingly, to minimize the

likelihood of a challenge to a plan on racial grounds, some mapmakers openly asserted that their driving motivation was to

draw the best partisan gerrymander possible. For example, the

district court in Rucho observed that, in North Carolina, Representative Lewis said that he “propose[d] that [the Committee]

draw the maps to give a partisan advantage to 10 Republicans

and 3 Democrats because [he] d[id] not believe it [would be] possible to draw a map with 11 Republicans and 2 Democrats.” Common Cause v. Rucho, 279 F. Supp. 3d 587, 604 (M.D.N.C. 2018),

vacated and remanded, 138 S. Ct. 2679.

26

(“Shape is relevant not because bizarreness is a necessary element of the constitutional wrong or a

threshold requirement of proof, but because it may be

persuasive circumstantial evidence … [of] the legislature’s dominant and controlling rationale in drawing

its district lines.”); see also, e.g., League of Women Voters, 178 A.3d at 775-76, 820-21 (2018) (describing testimony of Dr. John Kennedy regarding how specific

districts in the challenged map failed to satisfy traditional districting criteria and how the modification of

the prior map occurred in a directly partisan manner).

The same factors that assist in the “intensely local appraisal,” White v. Register, 412 U.S. 755 (1973), required in racial gerrymandering cases apply equally

to the partisan gerrymandering context.

CONCLUSION

For the foregoing reasons, the Court should hold

that partisan gerrymander claims are justiciable and

adopt the standard proposed for evaluating the constitutionality of partisan gerrymanders.

Respectfully submitted,

Thomas M. Bondy

Hannah Garden-Monheit

Elizabeth R. Cruikshank

ORRICK, HERRINGTON &

SUTCLIFFE LLP

1152 15th Street, NW

Washington, DC 20005

February 12, 2019

E. Joshua Rosenkranz

Counsel of Record

ORRICK, HERRINGTON &

SUTCLIFFE LLP

51 West 52nd Street

New York, NY 10019

(212) 506-5000

jrosenkranz@orrick.com