Considering the Prospects for Identifying a …Considering the Prospects for Identifying a...
Transcript of Considering the Prospects for Identifying a …Considering the Prospects for Identifying a...
Considering the Prospects for Identifying
a Gerrymandering Standard
Robin Besta
Shawn J. Donahueb
Jonathan Krasnoc
Daniel B. Maglebyd
Michael D. McDonalde
Abstract
Courts and the States themselves have found it difficult to rid redistricting processes of partisan manipulation The knotty problem, legally and procedurally, is that no proposed standard has found acceptance as a convincing means for identifying whether a districting plan is a partisan gerrymander with knowable harmful effects. We review five standards for curbing gerrymandering in order to diagnose their shortcomings and to see whether it might be possible to get purchase on what is needed to overcome them. We take as our perspective how easily manageable and effective each would be to apply at the time a redistricting authority decides where to draw the lines or, post hoc, when a court is asked to decide whether a gerrymander has been enacted. Upon review we conclude that a combination of the two symmetry standards offer the best prospects but only if recognize that gerrymandering’s harm takes two forms: diluting votes and curtailing speech.
_______________________________ Department of Political Science, Binghamton University, Binghamton, NY 13902-6000;
Phone; (607) 777-2252; FAX (607) 777-2675 a Assistant Professor of Political Science, [email protected] b PhD Student in Political Science, [email protected] c Associate Professor of Political Science, [email protected] d Assistant Professor of Political Science, [email protected] e Professor of Political Science, [email protected]
1
Partisan gerrymandering drains the energy and vitality from elections as
instruments of democracy. By packing one set of partisans in a small number of
districts, opposition partisans can maintain a legislative majority even without winning a
vote majority. By spreading one set of partisans evenly across very many districts, the
minority partisan voices in a legislative chamber can be all but silenced. Nevertheless,
despite the democratic infirmities associated with gerrymandering, policing let alone
eliminating the practice has proven difficult. The problem, legally and procedurally, is
that no proposed standard has found acceptance as a convincing means for identifying
whether a districting plan is a gerrymander with knowable harmful effects.
Justice Scalia, announcing the Court’s judgment in Veith, notes that “[t]he term
‘political gerrymander’ has been defined as ‘[t]he practice of dividing a geographical area
into electoral districts, often of highly irregular shape, to give a political party an unfair
advantage by diluting the opposition’s voting strength’” (Vieth v. Jubelirer, 2004, 271 n.
1, quoting Black’s Law Dictionary 1999, 696). Finding intention and observing weirdly
shaped districts are seldom difficult (as in Davis v. Bandemer 1986; Veith v. Jubilier
2004, LULAC v. Perry 2006), but finding a standard that identifies a party’s unfair
advantage because the opposition party’s votes have been diluted has proved elusive.
We review five proposed standards for identifying gerrymandering’s harmful
effects. All five have been presented to courts in recent years, but to date none has been
found actionable. Our purpose is to spot the shortcomings of each and to see whether it
might be possible to gain purchase on what is needed to surmount them. The five
include counting wasted votes for one set of partisans versus the other (Stephanopolous
and McGhee 2014), applying a vote-denominated symmetry test (McDonald and Best
2015), comparing the number of districts won in an enacted plan against expected wins
from a null set of neutrally drawn plans (Chen and Rodden 2013a), adopting a seat-
denominated symmetry test (Grofman and King 2007), and setting up a three-prong test
for proportionality, lack of responsiveness, and vote-denominated symmetry (Wang
2015). Stephanopolous and McGhee along with McDonald and Best concern themselves
principally with diluted votes; Chen and Rodden as well as Grofman and King focus
2
principally on unfairness to parties; and Wang tackles both unfairness to parties and
diluted vote weights.
At each turn in our reviews we take as our perspective how easily manageable and
effective each would be to apply at the time a redistricting authority decides where to
draw the lines or, post hoc, when a court is asked to decide whether a gerrymander has
been enacted. Our evaluations show that both counting wasted votes and comparing
actual to expected district wins are manageable but not effective; neither focuses on
structural features of the districting plan in direct association with gerrymandering.
Vote-denominated symmetry is both manageable and effective but applies only to
packing forms of gerrymandering. Seat-denominated symmetry applies to packing and
packing-plus-cracking gerrymanders, though not packing by itself, but is not entirely
manageable because its reading of gerrymanders is situational and requires reliance on
nonfactual hypotheticals. The three-prong approach fails on its own terms because the
prongs do not fit together as a coherent whole and, worse, can operate at cross-purposes.
All in all, the reviews lead to these surprising, tentative conclusions. Only the vote-
denominated symmetry standard is capable of identifying gerrymandering’s harm as
unfairness to a party because its supporters’ votes have been diluted. Expanding the
concept of harm to cover unfairness to a party as such requires extending the offense to
silencing or otherwise controlling the voice of the people in violation of the First
Amendment.
Wasted Votes
Counting and comparing wasted votes is the basis for the efficiency gap standard
proposed by and Stephanopoulos and McGhee (2015; see McGhee 2014 for the
underlying social science thinking). A 2015-16 challenge to Wisconsin’s Assembly
districts relies on it to charge partisan gerrymandering (Whitford v. Nichol 2015, cv-
421). The approach proceeds from the insight that both winners and losers “waste” votes
by inefficient allocation in an election. That is, any votes above the winning number for
the winner plus all votes for the loser are wasted in that they contribute nothing of
3
determinative importance to deciding who wins. So, in an election decided by a 60-40
margin, the winner wastes 10 percentage points above 50% (setting aside ties for the
sake of simplicity), while the loser wastes all 40 percentage points. Comparing the
magnitude of the waste on both sides, 10 versus 40, shows an efficiency gap (of 30
points) favoring the winner. McGhee and Stephanopoulos argue that in a non-
gerrymandered system both sides waste the same number of votes, so ideally the
efficiency gap should equal zero.
Their claim is appealingly simple, straightforward, and intuitive. We know that
gerrymanders function by inequitably allocating votes in some fashion. The question is
whether comparing inefficiencies in this way fares well as a manageable and effective
metric for detecting partisan gerrymanders.
On the question of manageability, its simple computation would seem to clear the
bar, but even the counting process is an open question.1 It runs into a second
manageability problem when deciding how many wasted votes signal a gerrymander.
Because no democratic or legal principle answers the question of how many wasted votes
are needed to say a plan is a gerrymander, the approach calls for comparisons to the
historical record in the same jurisdiction and contemporaneous results in other
jurisdictions. Such relative baselines beg the question of whether what occurred
previously in the same jurisdiction or is occurring contemporaneously in other
jurisdictions are results contaminated by gerrymandering.
Effectiveness, too, runs into two problems. First, and simply, under single-
member district rules votes are wasted for reasons other than gerrymandering. One
needs to look no further than a simple example of a congressional district in a one-
district state such as Delaware to see this. Unless the vote splits 75-25, one wastes more
votes than the other, this despite the fact that a gerrymander is impossible in a one-
district state. Maybe the efficiency gap is useful only in multi-district situations, but that
1 While the arithmetic is simple, and in that sense clears the bar, the definition of votes wasted by the winning candidate takes two forms. Andrew Hacker, who refers to the winner’s wasted votes as excess votes, defines them as one more than the votes received by the losing candidate (Hacker 1964, 55-7). McGhee (2014) and Stephanopolous and McGhee (2015) define a winner’s excess/surplus/wasted votes as votes beyond 50%+1.
4
can’t be true either. In a three districts state, a symmetrical distribution of 48-52-56 has
a gap of +8.3 in favor of the majority party and is, by the Stephanoplous and McGhee
criterion a gerrymander. Of course, if the vote shifted uniformly to 46-50-54, there is no
gerrymander, even though it is the same districting plan. Then, if votes shift another two
points to 44-48-52, the gerrymander would be said to run in the direction opposite of
what was inferred from the original 48-52-56 distribution. In fewer words, reading a
gerrymander from the efficiency gap can and often will vary depending on the
percentage level of the votes a party receives. Again we see, as in the one-district
example, that the efficiency gap is not solely recording a structural feature of the
districting plan as it relates to gerrymandering.
The second effectiveness problem is that a necessary condition for equalizing
wasted votes is a majoritarian seat-vote ratio of two to one (assuming equal turnout in all
districts and accepting the McGhee counting of wasted votes rather than Hacker’s; see
fn. 1). Every one percentage of the majority party’s vote above 50 wins that party an
additional two percent of the districts—55 percent of the vote wins 60 percent of the
seats. Why a two-to-one ratio is desirable is an open question, except to say that it
equalizes wasted votes. Equally damning, false positives and false negatives are likely to
abound. Perfectly symmetrical vote distributions can fail the two-to-one standard.2 As
well, a two-to-one ratio can be achieved precisely because a plan has a strong asymmetry
bias.3 So, despite the claim that the efficiency gap standard comports with and arises
from the idea of partisan symmetry, it doesn’t really.4
The wasted vote approach has clear intuitive appeal, and its computation is
easy—just count and compare wasted votes using straightforward arithmetic. Its
2 The 48-52-56 vote distribution discussed above offers a simple example of a false positive; 52 percent of the vote wins 66.7 percent of the seats—an 8.33 ratio instead of the 2.00 ratio. Thus, the efficiency gap identifies this plan as biased in favor of the majority party when it clearly is not.
3 A 40-40-60-65-70 vote distribution offers a simple example of a false negative. The distribution is asymmetrical (median 60 and mean 55), but the efficiency gap shows an equal number of wasted votes. Votes are five points above 50, and seats are ten points above 50. Thus the majoritarian ratio is two-to-one despite the asymmetry of the distribution.
4 See Stephanopoulos and McGhee (2015, 2-3 and passim) and Whitford v. Nichol (2015, 15-19) for claims about the relationship between symmetry and the efficiency gap.
5
downsides? Its definition of wasted votes is shaky. It under-achieves on the question of
manageability and overreaches on questions of effectiveness. While the arithmetic is
easy, evaluating the results requires using a relative comparison to the historical record
of elections in the same jurisdiction or to election results in other jurisdictions. A
historical comparison is liable to perpetuate gerrymanders in earlier years; comparison
to other jurisdictions leaves one wondering whether the baseline involves a mix of fair
and unfair outcomes elsewhere. Overreaching on effectiveness comes from two sources.
On is its variable reading of gerrymandering depending on the levels of the vote split
system wide. The other is the implied premise that single-member district elections are
completely fair if and only if they operate with a swing ratio of 2.0. Few single-member
district systems actually operate that way generally, and probably none do so
persistently. In effect, therefore, the wasted vote approach is an implicit indictment of
the single-member district rules. That is a nonstarter in American politics. It substitutes
a two-to-one majoritarian ratio for the view that fairness requires proportional
representation—i.e., a one to-one majoritarian ratio—which has not found acceptance in
American politics and law (Bandemer 1986, 129-30).
Vote-denominated Symmetry
The vote-denominated symmetry approach or, as McDonald and Best (2015)
refer to it, the equal vote weight standard, has been proposed by amici (Hebert and
Lang 2015) at the remedy stage of the Virginia litigation that earlier found the State’s
congressional districts to be an unconstitutional racial gerrymander (Page v. Virginia
State Board of Elections 2014). The approach relies on two easily observed facts: (1)
compare the median and mean district vote percentages, and (2) see whether majority
rule is violated. The point is to identify packing forms of gerrymandering on the thought
that packing is the prevalent form of gerrymandering alleged in recent decades. When
one group of partisans is relatively more packed than the other, a districting plan has the
potential to violate the widely embraced principle of equal vote weights and, from the
unequal weights, to entrench one party in majority status.
6
In all, the standard for a factual identification of a gerrymander rests on three
ideas.
1. Leading indicator: Asymmetrical packing exists when the median district vote
percentage for one party is persistently lower than its mean district vote
percentage.
2. Objectionable harm: A vote weight inequality is clearly identifiable when one
set of partisan voters casts a majority of the votes but carries less than a majority of
the districts, because violating majority rule occurs only when all votes do not
count equally.
3. Cause: District line placements are the known cause of the unequal vote weights.
Votes counted system-wide contribute equally to the count. Votes counted after
division into districts changes only the manner of counting. To the extent the two
forms of counting do not produce the same result the difference must be caused by
the line placements.
Its relative lack of aggressiveness in attacking gerrymandering comes from
majority rule’s central role in identifying gerrymandering as the cause of unequal vote
weights. This could prove disquieting in either of two situations.
In a jurisdiction with a predominant party, violations of majority rule are not
observed because one party always wins a vote majority. In this situation a median-
mean difference that violates majority rule is out of the question. So, for example, by
this standard the Texas congressional district, 2004 and 2010, could not be considered a
gerrymander because in those years Democrats never cast a vote majority for any Texas
office (McDonald and Best 2015, 327-8). A more aggressive symmetry requirement
could be used to challenge this sort of situation on two fronts. It could question whether
the majority party should be allowed to win an extra-large seat majority, somehow
defined. It could also be used to challenge the lack of responsiveness to vote shifts
because very many districts have been made noncompetitive—e.g., in Texas 28 of 32
districts didn’t undergo switched partisan control after the State Legislature drew the
lines in 2003.
7
Also tied to a focus on violating majority rule is this second disquieting situation.
Equal median and mean district vote percentages indicate only average symmetry, not
full-scale symmetry. Reaching for a full- or at least a fuller-scale approach would be
more aggressive. For example, a five district plan applied to two-party competition that
has (expected) Republican district vote percentages of 44, 46, 51, 52, and 62 is
symmetrical via the equal vote weight standard but asymmetrical under a full-scale
symmetry requirement. The median and mean are both 51. Thus, average symmetry is
upheld inasmuch deviations above and below the mean of 51 both average 6. Majority
rule is also preserved; the vote majority holds a 3 to 2 seat majority. Full-scale symmetry
goes wanting however, because something like uniform vote swings would result in
Republicans winning only three seats with 52 percent of the vote—an upward shift of 1
point resulting in a 45, 47, 52, 53, 63 distribution—but Democrats win 4 seats when they
have 52 percent of the vote—after a downward shift of three points resulting in a 41, 43,
48, 49, 59 distribution. While majority rule is maintained under both vote swings, the
idea of equality is strained because different rewards (seats) are acquired from the same
resources (votes).
The equal vote standard has pros and cons. It could be applied with relative ease.
The findings of fact are simple: compare the median and mean district percentages and
check for violations of majority rule. However, it is not as thoroughly effective as some
might demand. It holds predominant majorities safe from gerrymandering allegations,
and it under-reaches in situations when vote shifts could produce different seat
outcomes despite each party receiving the same vote percentages.
Comparison to a Null Set
This approach switches emphasis from diluted votes to unfairness to parties. If an
enacted plan is an outlier in a null set’s distribution, one can infer that it was probably
intended to hold a partisan advantage. As will soon become apparent, however, a crucial
question involves figuring out what characteristic needs to be evaluated in terms of its
distribution—districts won, perhaps the vote distribution’s number of competitive
8
districts, or perhaps its standard deviations, maybe its skewness, or maybe even its
kurtosis?5
Comparisons to a null set figured prominently in reports and testimony in the
challenge to Florida’s post-2010 congressional districts (i.e., Romo v. Detzner 2014).
The basic idea of using computers for this purpose has been around at least since
William Vickrey made the point more than a half-century ago (Vickrey 1961), and a few
pioneers succeeded in advancing the idea in modest ways in the 1960s and 70s (Nagel
xxxx; Engstrom and Wildgen 1977). With advances in processing speed, the approach
was ready for a full-scale application (e.g., Cirincione, Darling, and O’Rouke, 2000;
Altman and McDonald 2011; Chen and Rodden 2013a), or so it seemed in the run up to
the Florida proceedings. Both Darling along with Chen and Rodden produced null sets
(see Darling 2013; Chen and Rodden 2013b; 2014), and Rodden testify at length. In the
end, however, neither the reports nor Rodden’s testimony received any mention in the
trial court or subsequent court decisions.
For what it says about manageability, the court’s silence is disquieting. The
silence may have been benign. In the face of the smoking gun evidence of violating
Florida’s intent standard, the court might well have reasoned that nothing as
sophisticated as a null set was needed.6 Perhaps, however, the court was dissuaded from
crediting the method with probative value because one report identified a few contiguity
problems (Hodge 2013) and another report, plus testimony, questioned whether the
Chen-Rodden null set was randomly generated since no one can know the characteristics
of the population of all possible plans (McCarty 2013; 2014). Or, perhaps and more
simply, the black box nature of the method left the court unsure what reliable
conclusions could be drawn.
5 See Chen and Rodden (2013a) for an analysis that points to the number of wins; for the importance of the number of competitive districts see Engstrom and Wildgen (1977); on the standard deviation see, among others, Gudgin and Taylor (1979); on skewness see, among others, McDonald and Engstrom (1989); on kurtosis see Brady (1988).
6 The facts revealed such damning evidence as Republican legislators and their operatives enlisting mapmaking confederates to submit “citizen constructed plans” under fake names and writing scripts for “concerned citizens” to present the operatives’ ideas at public meetings (Romo v. Detzner 2014, 20-31).
9
Because the null set approach has yet to be tried and tested in a full form
application, questions about its effectiveness are open. Still, this much can be said. Not
much thought has gone into how the null set could be used to detect gerrymandering
beyond forming a baseline to say whether an enacted plan is an outlier in the null set
distribution and, on that basis, probably indicates a gerrymander. Engstrom and
Wildgen (1977, 469-70) evaluate a plan in regard to how many competitive districts it
contains. Cirincione et al. (2000), Darling (2013), along with Chen and Rodden (2013a,
2014) evaluate a plan in regard to the number of districts in which each racial group or
political party holds a majority. We have to suppose that focusing solely on the central
tendency is not enough. Why? Missing versus hitting the mark of the central tendency
leaves one wondering what, if any, harm has been created. Of the large number of plans
a computer can draw, the expected number of competitive districts or of majority-held
districts is liable to include some proportion that square with the expectation—i.e., the
central tendency—but involve differential packing, differential cracking, or both.
As example of the problems encountered when focusing on a central tendency
consider Chen and Rodden’s attempt to indicate a gerrymander by counting Bush or
McCain district wins across Florida, in both their academic and trial related work (Chen
and Rodden 2013a, 2013b, 2014). As noticed and noted by Darling (2013) and by
McCarty (McCarty 2013; 2014), a match or mismatch between expected and observed
number of districts carried is not a per se robust and structural feature of a districting
plan. The match or mismatch varies depending on the vote percentage won (this is a
problem similar to that encountered when using the efficiency gap). A packing
gerrymander that all but guarantees that a party win, say, 55 percent of the districts
whether it wins, say, 40, 50, or 60 percent of the vote—which is the type of result a
packing gerrymander can and often does produce—will sometimes match the expected
number of districts carried and other times will not, depending on a party’s system-wide
vote percentage. In different words, the contours of a districting plan interact with a
party’s system-wide level of support to produce more, equal, or fewer than expected
10
wins. As a consequence, the interaction produces variable readings of whether one and
the same plan is or is not a gerrymander.7
Using computer generated districts to form a null set holds promise. It removes
all but inadvertent partisan effects in its construction of a null set and thus supplies a
strong basis for probabilistic inferences about intentions. One problem it has to
overcome is making the computer processing more intuitive and transparent. Another
pressing matter is choosing a benchmark other than the expected number of competitive
districts or the number of district wins. The question is this: by what guidelines, by what
standard, can we know a partisan gerrymander has been chosen versus avoided? The
approach supplies a useful tool, but we need to figure out how to make it transparent and
how to use it effectively.
Seat-denominated Symmetry
A proposal for a seat-denominated symmetry approach goes back decades
(Gelman and King 1994). It has found favor among political scientists (e.g., Engstrom
2013; McGann at al. 2015; 2016). To some extent it has also found favor among
members of the Supreme Court when amici (King et al. 2005) proposed it for
consideration in LULAC v. Perry (2006; for a detailed discussion of the Justices’
positions taken on the approach see Grofman and King (2007, 1-6).
The approach, which Grofman and King refer to simply as a partisan symmetry
standard, relies on an equal opportunity notion of fairness. Within practical and
probabilistically knowable limits, each party is expected to win the same seat percentage
for the same vote percentage. If 55 percent of the vote results in Democrats winning 7 of
10 seats, 70 percent, then Republicans should win 70 percent of the seats when they win
55 percent of the vote. The partisan symmetry standard shares the same concern for
7 Darling analyzed his 5,000 map null set for nine pre-2012 statewide Florida elections in addition to the McCain-Obama presidential contest. For the McCain-Obama contest he found, as did Chen and Rodden, the expected number of McCain wins under the 2012 lines was 14, whereas the enacted districting plan had McCain wining 17—a result observed in less than one percent of the null set plans. However, his analysis of the nine other elections showed the actual versus expected wins either matched (three elections), differed by one in favor of Republicans (three elections), or differed by one or two in favor of Democrats (three elections).
11
asymmetry that violates majority rule as the vote-denominated approach, but it adds a
requisite symmetrical operation of the swing ratio. In the competitive range of two-party
vote splits, perhaps inside the 40 to 60 range, if Democrats win one more seat with an
additional three percent of the vote, then Republicans should be expected to add one seat
when their vote increases by three percentage points. Its attention to the swing ratio
bears a similarity to the wasted vote approach; however, it deviates by being agnostic
about the magnitude of the ratio, provided that the effect of the swing is symmetric.
The approach runs into three difficulties, two principled and one practical. One
principled difficulty is that the harm it identifies is not directly connected to voters.
Another is that when the harm exists it could be situational rather than fixed. The
practical problem is producing assurance that the situational harm is recognizable.
The simplest way to see both principled complications is by returning to the
examples used to point to a shortcoming of the vote-denominated approach. There we
had a five Democratic two-party percentage district vote distribution of 44, 46, 51, 52,
and 62. The median and mean are equal and therefore vote-denominated asymmetry as
a leading indicator of gerrymandering is missing. However, as discussed above, a three
point uniform shift in favor of the Republicans, moving the median and mean to 54,
leaves them with three district wins, while a three point swing in favor of Democrats
leads to four district wins. The different outcomes signal differential treatment
disadvantaging Republicans, but it is not clear that a vote weight difference is necessarily
implied. In both situations, majority rule is maintained. Thus we do not know based on
the majority rule marker that votes are unequally weighted. What we do know is that the
swing is not symmetrical. With Republicans at 52 through 57 percent of the vote they
win three districts, but with Democratic votes at 52 through 57 percent they win four
districts. Are those facts enough to say Republican votes carry less weight than
Democratic votes? Yes, perhaps, in that range of circumstances. If, however, the vote
swings a uniform 7 points in favor of Republicans, giving them 58 percent, they win 5
districts; but at 58 percent of the vote Democrats win only 4 districts. In that situation,
Republicans are advantaged and, thus, seemingly have a vote weight advantage. Again,
12
we do not know that votes count differently, because, at all levels of the vote, majority
rule is preserved. What we do know is that in some situations Democrats are
advantaged, and in other situations Republicans are advantaged. The differential
treatment is situational.
Because we cannot say with assurance that votes are weighted unequally in the
scenarios presented, given there is no violation of majority rule at any vote level, the
most we can say is that the votes count differently. How differently? That depends on
nature and magnitude of swing in each district. Therein resides the practical problem. If
the swing is uniform and a 3 point uniform swing toward Democrats is more likely than a
5 point uniform swing toward the Republicans, then Republicans do not have the same
opportunity as Democrats to win four seats. If the swing is non-uniform—i.e., mixed in
the sense that some districts swing more than others—we need to know more, much
more. Getting an assured handle on what else we need to know was the apparent
stopping point for Justice Kennedy when he remarked favorably on a seat-denominated
symmetry approach but said courts are “wary of adopting a constitutional standard that
invalidates a map based on unfair results that would occur in a hypothetical states of
affairs” (LULAC v Perry 2006, 420).
The partisan symmetry standard is more comprehensive than the equal vote
standard. It takes account of both packing and cracking effects. To do so, however, it
can overreach in principle by locating the harm as unequal treatment of parties whether
or not we can know that voters suffer harm. It can also overreach in practice by
requiring a supporting analysis that makes some decision makers wary of enforcing it.
Three-prong approach
Because an effective gerrymander can be achieved through so-called packing,
cracking, and their combination, it would seem a good idea to use multiple criteria to
identify them. That is the apparent thought standing behind Samuel Wang’s proposed
three-prong test (Wang 2015a). In an amicus brief to the Supreme Court in Harris v.
Arizona Redistricting Commission (2016), Wang proposed adopting his ideas as a basis
13
for ruling that the Commission’s actions do not amount to a gerrymander (Wang
2015b).8
Wang’s three prongs are grounded in concerns for (a) a less than justifiable
degree of seat-vote proportionality, (b) under-responsiveness of seat shifts from vote
shifts, and (c) asymmetry in the vote distribution.
1. Proportionality: Seat to vote responsiveness is within a range between
proportionality and what could be expected from the seat-vote relationship in
other states (plus allowance for random variation).
2. Under-responsive seat shifts to vote shifts: This is indicated by
unequal average lopsidedness in the vote distribution, unequal average values
of each party’s winning margin above 50 (plus allowance for random
variation).
3. Symmetry: A party’s median district percentage equals its mean district
percentage (plus allowance for random variation).
Giving consideration to three prongs has the appearance of a more
comprehensive set of concerns than the preceding four approaches. That much can be
granted, but having three prongs to deal with creates manageability problems. For
instance, Wang advises in one statement that the three prongs can be used “separately or
together” (Wang 2015a, 22), but he later advises that the degree of proportionality
(prong 1) might often be ignored except to serve as a substitute when the others are
impossible to apply (Wang 2015a, 46). Natural questions are these: is satisfying one of
the prongs enough to say no gerrymander exists; is violating one of the prongs enough to
say a gerrymander does exist?
8 His amicus proposal appears to have misapprehended the issue in Arizona. Appellants claimed that the Commission gerrymandered by under-populating districts favoring Democrats. If true, the bias introduced is a form of malapportionment/turnout bias, which requires a comparison that Wang did not take into account. That is, Wang proposed a median-mean comparison in order to indicate advantaged gained from under-populated districts, but to make the proper comparison for turnout bias the mean district vote percentage needs to be compared to the statewide vote percentage, not to the median district percentage (see McDonald and Best 2015, 317-8).
14
Managing the three prongs separately or together is also a fundamental concern
for questions of effectiveness. The different prongs can provide indications running in
opposite directions. For example, a five district distribution of 40, 40, 60, 60, 60,
satisfies both proportionality (prong 1) and equal average lopsidedness (prong 2) but
fails the symmetry standard of prong 3 (median 60 and mean = 52). A swing ratio could
reside within the bounds of acceptable proportionality but fail on both lopsidedness and
symmetry. And, a districting plan could fail the lopsidedness test due to incumbency
effects, if one party has more incumbents running, even in the absence of
gerrymandering. Who decides how many prongs to apply? Requiring failure on all three
prongs simultaneously leaves an opportunity for the original mapmakers to satisfy any
one prong of their choosing while enacting a gerrymander that would be indicated by
either or both of the other two prongs. In all, and in other words, the three prongs do
not work together as a coherent framework.
Evaluating gerrymanders through three different tests has an intuitive feel.
However, it raises difficult questions of both manageability and effectiveness because, as
it stands, no compelling coordinating principle supplies clarity about whether a
gerrymander exists.
What Can Be Done?
Our review indicates that the key to identifying and combatting partisan
gerrymanders requires putting symmetry at the forefront. This is in part a result of a
process of elimination and in part an implication of symmetry squaring with the
definition of gerrymandering’s harm. The efficiency gap and the three-prong approach
are nonstarters. The efficiency gap has to be eliminated as a viable approach because its
core concept of wasted votes may relate to gerrymandering in some circumstances but
clearly is not an indicator of any structural feature of a district plan having to do directly
with gerrymandering. The Wang three-prong approach is ambitious but lacks a coherent
structure upon which one could sustain a conclusion that a district plan is or is not a
gerrymander. The null set approach is a starter. However, its black box nature has to be
15
made transparent. Also, its focus has to be on something other than the number of
districts wins outside typical expectations because expected wins are a variable
consequence matching and mismatching actual wins depending on a party’s level of
support.
It is not just that the symmetry approaches are preferred by default. A focus on
symmetry stays true to the harm element in gerrymandering’s definition. It identifies
favorableness to one party by diluting votes for the other party. One can’t help but
notice, however, the two symmetry tandards do so as a duality. Vote-denominated
symmetry emphasizes vote dilution; seat-denominated symmetry emphasizes party
favoritism. It is preferred to join the two, allowing their union to speak to both
definitional elements. Unfortunately, their union by simple means poses a problem. If
the notion of harm is to be read as a conjoined concept, wherein un-favorableness to a
party is necessarily the consequence of vote dilution, seat denominated symmetry has
nothing to add to vote-denominated symmetry. Seat-denominated symmetry identifies
vote dilution as the source of un-favorableness if and only if vote-denominated
symmetry has already reached the same conclusion.
We consider this unfortunate because it disregards the widely held sense that
gerrymandering tilts the partisan playing field even if it does not do so solely by diluting
votes. In what sense does the tilted field have a connection to voters? The answer in an
extreme circumstance is that a gerrymander can silence minority voices by creating
super-majoritarian results,9 such as when a congressional delegation is composed of
members of one political party across an entire decade. In more limited circumstances,
manipulation of the swing ratio, which is an important concern for seat-denominated
symmetry, can distort the voice of the people to the liking of the government charged
with drawing the districts. As we see it, therefore, it is not that harm to a political party
9 This could be relevant to situations when a congressional delegation is composed of members of one political party across an entire decade. The outcomes in Massachusetts or Nebraska between 2002 and 2012 could be instances of super-majoritarian cracking; no Republican won election to the U.S. from Massachusetts and no Democrat won election from Nebraska during that time. Of course, detailed checks are required before being able to say whether gerrymandering or something else stands behind these outcomes.
16
as such is outside the harm produced by gerrymandering. Rather, the harms are
twofold: vote-denominated symmetry is an indicator of violations of equal protection;
seat denominated symmetry is an indicator of violations of silencing or distorting
speech, speech that is a keystone element of the democratic process.
Conclusion
The task we set for ourselves here has been to engage in a diagnostic for the
purpose of gaining insight as to why it has proved so difficult to establish a standard for
detecting gerrymanders. On that score, if only on that score, we have made some
headway. The efficiency gap, a null set focused on observed versus expected district
wins, and Wang’s three-prong approach can be set to the side as unworkable. Symmetry
stands up as a plausible and useful standard, but the duality embedded in the concept
requires a redefinition of the duality of the harms that gerrymander can produce.
The missing element in the equal vote weight standard (vote-denominated
symmetry) is taking account of the manipulated swing ratios. The missing element in
the partisan symmetry standard (seat-denominated symmetry) is an assurance that votes
have been diluted. To move beyond diagnosis to prescription is a long step that we are
not yet prepared to take. Our proposal for combining the duality of the symmetry
standards is to insist on two requirements to hold safe a plan from the charge that it is
likely to produce one or another of gerrymandering’s two harms: plausible evidence that
(1) majority rule is unlikely and unnecessarily persistently violated and (2) a plan does
not have an anomalous swing ratio.
17
References
Altman, Micah & Michael P. McDonald. 2011. “BARD: Better Automated Redistricting.”
Journal of Statistical Software 42: 2-36.
Brady, David W. 1988. Critical Elections and Congressional Policy Making. Stanford,
CA: Stanford University Press.
Chen, Jowei and Jonathan Rodden. 2013a. “Unintentional Gerrymandering: Political
Geography and Electoral Bias in Legislatures.” Quarterly Journal of Political
Science 8: 239-69.
Chen, Jowei and Jonathan Rodden. 2013b. “Report on Computer Simulation of Florida
Congressional Districting Plans” (February 15). Available at Justin Levitt’s All
about Redistricting website.
Chen, Jowei and Jonathan Rodden. 2014. “Response to Expert report of Stephen W.
Hodge” (February 18). Available at Justin Levitt’s All about Redistricting
website.
Cirincione, Carmen, Thomas A. Darling, and Timothy O’Rourke. 2000. “Assessing
South Carolina’s 1990 Congressional Districting.” Political Geography 19: 189-
211.
Darling, Thomas A. 2013. “Report of Thomas A. Darling in Romo v. Detzner” (April 8).
Available at Justin Levitt’s All about Redistricting website.
Davis v. Bandemer. 1986. 478 U.S. 109.
Engstrom, Erik J. 2013. Partisan Gerrymandering and the Construction of American
Democracy. Ann Arbor, MI: University of Michigan Press.
Engstrom, Richard L. and John K. Wildgen. 1977. “Pruning Thorns from the Thicket:
An Empirical Test of the Existence of Racial Gerrymandering.” Legislative
Studies Quarterly 2:465-79.
Gelman, Andrew and Gary King. 1994a. “A Unified Method of Evaluating Electoral
Systems and Redistricting Plans.” American Journal of Political Science 38: 514-
54.
Grofman, Bernard N. 1983. Measures of Bias and Proportionality in Seats-Votes
Relationships. Political Methodology, 9:295-327.
18
Grofman, Bernard N. and Gary King. 2008. “The Future of Partisan Symmetry as a
Judicial Test for Partisan Gerrymandering after LULAC v. Perry.” Election Law
Journal 6: 2-35.
Gudgin, Graham and Peter J. Taylor. 1979. Seat, Votes, and the Spatial Organisation of
Elections. London, UK: Pion.
Hacker, Andrew. 1964. Congressional Districting: The Issue of Equal Representation
(revised ed.). Washington, DC: Brookings.
Harris v. Arizona Independent Redistricting Commission. 2016. U.S. Supreme Court
(slip opinion).
Hebert, J. Gerald and Danielle Lang. 2015. “Memorandum of Amici Curiae Common
Cause and Virginia New Majority Regarding Proposed Remedial Plans.” U.S.
District Court for the Eastern District of Virginia (3:13-cv-678).
Hodge, Stephen W. 2013. “Assessments of the Redistricting Simulations of Professors
Chen and Rodden” (November). Available at Justin Levitt’s All about
Redistricting website.
Hill v. Detzner. 2015. No. 3:15-cv-00380 (N.D. Fla.).
King, Gary, Bernard Grofman, Andrew Gelman, and Jonathan Katz. 2005. “Amicus
Brief in Jackson v. Perry Submitted on Behalf of Neither Party, in the Supreme
Court (No. 05-276).
LULAC v. Perry. 2006. 548 U.S. 399.
McCarty, Nolan. 2013. “Response to Chen and Rodden’s ‘Report on Computer
Simulation of Florida Congressional Districting Plans’” (No data stated).
Available at Justin Levitt’s All about Redistricting website.
McCarty, Nolan. 2014. “Response to Jowei Chen and Jonathan Rodden’s February,
2014 Report” (April 28). Available at Justin Levitt’s All about Redistricting
website.
McDonald, Michael D. and Richard L. Engstrom. 1989. "Detecting Gerrymanders." In
Bernard Grofman (ed.) Toward Fair and Effective Representation: Political
Gerrymandering and the Courts. New York, NY: Agathon, 178-202.
McDonald, Michael D. and Robin E. Best. 2015. “Unfair Partisan Gerrymandering in
Politics and Law: A Diagnostic Applied to Six Cases.” Election Law Journal 14:
312-30.
19
McGann, Anthony J., Charles Antony Smith, Michael Latner, and Alex J. Keena. 2015. “A
Discernable and Manageable Standard for Partisan Gerrymandering.” Election
Law Journal 14: 295-311.
McGann, Anthony J., Charles Antony Smith, Michael Latner, and Alex J. Keena. 2016.
Gerrymandering in America: The House of representative, the Supreme Court
and the Future of Popular Sovereignty. New York: Cambridge University Press.
McGhee, Erin. 2014. “Measuring Partisan Bias in Single-Member District Electoral
Systems.” Legislative Studies Quarterly 55: 68–69.
Nagel, Stuart. 1965. Simplified Bipartisan Computer Redistricting.” Stanfor Law
Review 17: 863-69.
Page v. Virginia State Board of Elections. 2014. U.S. District Court for the Eastern
District of Virginia (3:13-cv-678).
Romo v. Detzner 2012. Final Judgement, 2nd Judicial Circuit Court (CA-412).
Stephanopoulos, Nicholas and Eric McGhee. 2015. “Partisan Gerrymandering and the
Efficiency Gap.” University of Chicago Law Review 82: 831-900.
Tufte, Edward R. 1973. “The Relationship between Seats and Votes in Two-Party
Systems.” American Political Science Review 67: 540-54.
Vickery, William. 1961. “On the Prevention of Gerrymandering.” Political Science
Quarterly. 76; 105-10.
Wang, Samuel S.-H. 2015a. “A Three-prong Standard for Practical Evaluation of
Partisan Gerrymandering” (December version). Available at SSRN, id=2671607.
Wang, Samuel S.-H. 2015a. “Brief of Amicus Curiae Samuel S. Wang, Ph.D. in Support
of Appellees.” U.S. Supreme Court, Harris v. Arizona Independent Redistricting
Commission (14-232).
Whitford v. Nichol. Case: 3:15-cv-00421. (Wisc. E.D. 2015).
Veith v. Jubelirer. 2004. 541 U. S. 267.
20