Partisan gerrymandering enjoys a much longer history in the US than racial gerrymandering. Prior to elections for the first Congress, Virginia Governor Patrick Henry famously reconfigured the Fifth Congressional district and engineered a change in the state law regarding residency for purposes of disadvantaging Federalist James Madison in favor of Anti-Federalist friend James Monroe. Henry's efforts failed. This wasn't the first case of partisan (AKA political) gerrymandering. The very term “gerrymander” is a portmanteau coined in reference to an 1812 case of partisan district map-drawing in Massachusetts.
But it was only in 1986, with Davis v. Bandemer, that the Court affirmed that claims of partisan gerrymandering are justiciable under the Equal Protection Clause, analogizing it to racial gerrymandering (though in earlier challenges to district maps on grounds of unequal populations, partisan gerrymandering was extensively discussed, and a concurrence even referred to it as unconstitutional). The Bandemer plaintiffs argued that Indiana's 1981 districting plan was unconstitutional primarily on the basis of the results of the 1982 election for the House, in which Democratic candidates received 51.9% of votes cast statewide but only 43% of the seats. In contrast, Democratic candidates for the Senate received 53.1% of the votes cast statewide, and 13 (52%) out of the 25 Democratic candidates were elected.
Only a plurality joined Justice White's decision, which informed that in order to succeed in a partisan gerrymander claim, plaintiffs must “prove both intentional discrimination against an identifiable political group and an actual discriminatory effect on that group.” But beyond those general requirements, the Court was unable to articulate a judicially discernible and manageable standard for determining when district map-drawing is a case of unconstitutional partisan gerrymandering. While the plurality stated that discriminatory effects would presumably support a finding of discriminatory intent in the record, insofar as determining discriminatory effects, the plurality only gave clues to what they are not--except for one sentence thrown in for comic relief:
Of course, no one knows what that last sentence means. There is no group of people with greater animus toward and willingness to legally harm another group than are staunch members of opposing political parties. There also does not seem to be any intelligible distinction between “a particular apportionment scheme [that] makes it more difficult for a particular group in a particular district to elect the representatives of its choice” and “unconstitutional discrimination [that occurs] when the electoral system is arranged in a manner that will consistently degrade a voter's or a group of voters' influence on the political process as a whole.” What is the difference between what those two clauses are saying?
Evidently Justice White was trying to reiterate the already acknowledged facts that (1) there is no possible way to draw districts in order to guarantee perfect proportionality of seats to votes, where each political party will elect 50% of the representatives when casting 50% of the votes, therefore proportional election outcomes can't be the measuring stick for partisan gerrymandering; and (2) that whenever legislators draw a district map, one can only assume that there are partisan considerations that are hoped to have partisan effects. As he had already quoted Robert Dixon, “ . . . there are no neutral lines for legislative districts . . . every line drawn aligns partisans and interest blocs in a particular way different from the alignment that would result from putting the line in some other place."
In any case, due to insufficient proof of a discriminatory effect, the Court declined to strike down Indiana's redistricting scheme.
And despite hearing several challenges since, the Court has still been unable to formulate a judicially discoverable and manageable standard for distinguishing between permissible district maps and unconstitutional partisan gerrymanders. In Vieth v. Jubelirer (2004), another Opinion that attracted only a 4-member plurality, partisan gerrymandering claims were asserted to be nonjusticiable, dismissing the complaint. Justice Kennedy concurred in judgment, agreed that there is no judicially manageable standard for deciding such challenges, but dissented on the plurality's finding that a partisan gerrymandering claim cannot be a cause of action. Thus Kennedy single-handedly rescued partisan gerrymandering claims from the scrap heap of lost causes. (It's surely of interest that the plaintiffs' party won the majority of the state's congressional seats in the 2 elections following the dismissal of the suit.)
And so it came to pass that another state's district map has recently been challenged on grounds of unconstitutional partisan gerrymandering: Wisconsin's Assembly district plan adopted in 2012 by the newly elected Republican majority. In this case, plaintiffs proposed measuring a discriminatory effect in election results by way of an “efficiency gap” (EG), and urged the court to adopt this method for assessing partisan gerrymandering. The district court's majority Opinion described the EG thus:
OK, got it.
The majority Opinion reports that plaintiffs' expert witness (Stanford professor of political science and statistics Simon Jackman) “conducted an historical analysis of redistricting plans which compared the trends in efficiency gaps across a wide variety of states over the last forty years (a total of 786 state legislative elections). He observed that an EG in the first year after a districting plan is enacted bears a relatively strong relationship to the efficiency gap over the life of a plan. The party that 'wastes' more votes in the first election year is likely to continue 'wasting' more votes in future elections.” Jackman further testifed that any districting plan that yields an EG above 7% (or below -7%) in its first election should be considered presumptively unconstitutional, as, according to him, this is the point in which the EG is unlikely to switch signs during the duration of the plan. On this footing, plaintiffs argued that Wisconsin's plan should be considered presumptively unconstitutional (triggering a burden-shift) due to the results of the 2012 and 2014 elections in which there were (according to Jackson's “simplified method” of calculating the EG) efficiency gaps of roughly 13% and 10% respectively in favor of Republicans.
But it was only in 1986, with Davis v. Bandemer, that the Court affirmed that claims of partisan gerrymandering are justiciable under the Equal Protection Clause, analogizing it to racial gerrymandering (though in earlier challenges to district maps on grounds of unequal populations, partisan gerrymandering was extensively discussed, and a concurrence even referred to it as unconstitutional). The Bandemer plaintiffs argued that Indiana's 1981 districting plan was unconstitutional primarily on the basis of the results of the 1982 election for the House, in which Democratic candidates received 51.9% of votes cast statewide but only 43% of the seats. In contrast, Democratic candidates for the Senate received 53.1% of the votes cast statewide, and 13 (52%) out of the 25 Democratic candidates were elected.
Only a plurality joined Justice White's decision, which informed that in order to succeed in a partisan gerrymander claim, plaintiffs must “prove both intentional discrimination against an identifiable political group and an actual discriminatory effect on that group.” But beyond those general requirements, the Court was unable to articulate a judicially discernible and manageable standard for determining when district map-drawing is a case of unconstitutional partisan gerrymandering. While the plurality stated that discriminatory effects would presumably support a finding of discriminatory intent in the record, insofar as determining discriminatory effects, the plurality only gave clues to what they are not--except for one sentence thrown in for comic relief:
. . . the mere fact that a particular apportionment scheme makes it more difficult for a particular group in a particular district to elect the representatives of its choice does not render that scheme constitutionally infirm. This conviction, in turn, stems from a perception that the power to influence the political process is not limited to winning elections. An individual or a group of individuals who votes for a losing candidate is usually deemed to be adequately represented by the winning candidate, and to have as much opportunity to influence that candidate as other voters in the district. We cannot presume in such a situation, without actual proof to the contrary, that the candidate elected will entirely ignore the interests of those voters. This is true even in a safe district where the losing group loses election after election. Thus, a group's electoral power is not unconstitutionally diminished by the simple fact of an apportionment scheme that makes winning elections more difficult, and a failure of proportional representation alone does not constitute impermissible discrimination under the Equal Protection Clause. See Mobile v. Bolden, 446 U.S. at 446 U. S. 111, n. 7 (MARSHALL, J., dissenting).
As with individual districts, where unconstitutional vote dilution is alleged in the form of statewide political gerrymandering, the mere lack of proportional representation will not be sufficient to prove unconstitutional discrimination. . . Rather, unconstitutional discrimination occurs only when the electoral system is arranged in a manner that will consistently degrade a voter's or a group of voters' influence on the political process as a whole.
As with individual districts, where unconstitutional vote dilution is alleged in the form of statewide political gerrymandering, the mere lack of proportional representation will not be sufficient to prove unconstitutional discrimination. . . Rather, unconstitutional discrimination occurs only when the electoral system is arranged in a manner that will consistently degrade a voter's or a group of voters' influence on the political process as a whole.
Of course, no one knows what that last sentence means. There is no group of people with greater animus toward and willingness to legally harm another group than are staunch members of opposing political parties. There also does not seem to be any intelligible distinction between “a particular apportionment scheme [that] makes it more difficult for a particular group in a particular district to elect the representatives of its choice” and “unconstitutional discrimination [that occurs] when the electoral system is arranged in a manner that will consistently degrade a voter's or a group of voters' influence on the political process as a whole.” What is the difference between what those two clauses are saying?
Evidently Justice White was trying to reiterate the already acknowledged facts that (1) there is no possible way to draw districts in order to guarantee perfect proportionality of seats to votes, where each political party will elect 50% of the representatives when casting 50% of the votes, therefore proportional election outcomes can't be the measuring stick for partisan gerrymandering; and (2) that whenever legislators draw a district map, one can only assume that there are partisan considerations that are hoped to have partisan effects. As he had already quoted Robert Dixon, “ . . . there are no neutral lines for legislative districts . . . every line drawn aligns partisans and interest blocs in a particular way different from the alignment that would result from putting the line in some other place."
In any case, due to insufficient proof of a discriminatory effect, the Court declined to strike down Indiana's redistricting scheme.
And despite hearing several challenges since, the Court has still been unable to formulate a judicially discoverable and manageable standard for distinguishing between permissible district maps and unconstitutional partisan gerrymanders. In Vieth v. Jubelirer (2004), another Opinion that attracted only a 4-member plurality, partisan gerrymandering claims were asserted to be nonjusticiable, dismissing the complaint. Justice Kennedy concurred in judgment, agreed that there is no judicially manageable standard for deciding such challenges, but dissented on the plurality's finding that a partisan gerrymandering claim cannot be a cause of action. Thus Kennedy single-handedly rescued partisan gerrymandering claims from the scrap heap of lost causes. (It's surely of interest that the plaintiffs' party won the majority of the state's congressional seats in the 2 elections following the dismissal of the suit.)
And so it came to pass that another state's district map has recently been challenged on grounds of unconstitutional partisan gerrymandering: Wisconsin's Assembly district plan adopted in 2012 by the newly elected Republican majority. In this case, plaintiffs proposed measuring a discriminatory effect in election results by way of an “efficiency gap” (EG), and urged the court to adopt this method for assessing partisan gerrymandering. The district court's majority Opinion described the EG thus:
The EG calculation is relatively simple. First, it requires totaling, for each party, statewide, (1) the number of votes cast for the losing candidates in district races (as a measure of cracked voters), along with (2) the number of votes cast for the winning candidates in excess of the 50% plus one votes necessary to secure the candidate’s victory (as a measure of packed voters).[273] The resulting figure is the total number of “wasted” votes for each party. [274] These wasted vote totals are not, of themselves, independently significant for EG purposes; rather, it is the comparative relationship of one party’s wasted votes to another’s that yields the EG measure.[275] The EG is the difference between the wasted votes cast for each party, divided by the overall number of votes cast in the election.[276] When the two parties waste votes at an identical rate, the plan’s EG is equal to zero.[277] An EG in favor of one party (Party A), however, means that Party A wasted votes at a lower rate than the opposing party (Party B). [278] It is in this sense that the EG is a measure of efficiency: because Party A wasted fewer votes than Party B, Party A was able to translate, with greater ease, its share of the total votes cast in the election into legislative seats. Put simply, an EG in Party A’s favor means it carried less electoral dead weight; its votes were, statistically, more necessary to the victories of its candidates, and, consequently, it secured a greater proportion of the legislative seats than it would have secured had Party A and Party B wasted votes at the same rate.
In a related sense, the EG can be viewed as a measure of the proportion of “excess” seats that a party secured in an election beyond what the party would be expected to obtain with a given share of the vote.[279] In a purely proportional representation system, a party would be expected to pick up votes and seats at a one-to-one ratio, i.e., for every additional percentage of the statewide vote the party gains, it should also gain a percentage in the share of the seats.[280] Based on decades of observed historical data, however, the parties’ experts agreed that with single-member, simple-plurality systems like Wisconsin’s, we can expect that for every 1% increase in a party’s vote share, its seat share will increase by roughly 2%. [281] Thus, a party that gets 52% of the statewide vote should be expected to secure 54% of the legislative seats. If the party instead translates its 52% of the vote into 58% of the seats, the district plan has demonstrated an EG of 4% in favor of that party (the difference between the expected seat share and the actual seat share).
In a related sense, the EG can be viewed as a measure of the proportion of “excess” seats that a party secured in an election beyond what the party would be expected to obtain with a given share of the vote.[279] In a purely proportional representation system, a party would be expected to pick up votes and seats at a one-to-one ratio, i.e., for every additional percentage of the statewide vote the party gains, it should also gain a percentage in the share of the seats.[280] Based on decades of observed historical data, however, the parties’ experts agreed that with single-member, simple-plurality systems like Wisconsin’s, we can expect that for every 1% increase in a party’s vote share, its seat share will increase by roughly 2%. [281] Thus, a party that gets 52% of the statewide vote should be expected to secure 54% of the legislative seats. If the party instead translates its 52% of the vote into 58% of the seats, the district plan has demonstrated an EG of 4% in favor of that party (the difference between the expected seat share and the actual seat share).
OK, got it.
The majority Opinion reports that plaintiffs' expert witness (Stanford professor of political science and statistics Simon Jackman) “conducted an historical analysis of redistricting plans which compared the trends in efficiency gaps across a wide variety of states over the last forty years (a total of 786 state legislative elections). He observed that an EG in the first year after a districting plan is enacted bears a relatively strong relationship to the efficiency gap over the life of a plan. The party that 'wastes' more votes in the first election year is likely to continue 'wasting' more votes in future elections.” Jackman further testifed that any districting plan that yields an EG above 7% (or below -7%) in its first election should be considered presumptively unconstitutional, as, according to him, this is the point in which the EG is unlikely to switch signs during the duration of the plan. On this footing, plaintiffs argued that Wisconsin's plan should be considered presumptively unconstitutional (triggering a burden-shift) due to the results of the 2012 and 2014 elections in which there were (according to Jackson's “simplified method” of calculating the EG) efficiency gaps of roughly 13% and 10% respectively in favor of Republicans.
