The term “gerrymandering” refers to a political tactic that in the United States goes back to the eighteenth century—the tactic of configuring electoral districts to favor the party that does the configuring, or to achieve some other non-neutral political goal: for example, reducing minority representation in the legislature by drawing district boundaries in such a way as to pack most of the minority voters into a handful of districts, thus minimizing the number of legislators whom they can elect. The Supreme Court held racial gerrymandering unconstitutional—a violation of the equal protection of the laws—in 1960. But the Court has refused to hold that “partisan” gerrymandering, which means configuring districts so as to favor the party that controls the legislature doing the districting, is unconstitutional.
Article I of the Constitution provides in section 4 that “The Times, Places and Manner of holding Elections for ... [members of the federal House of] Representatives, shall be prescribed in each State by the Legislature thereof; but the Congress may at any time by Law make or alter such Regulations.” The Supreme Court has required, in the name of equal protection of the laws, that congressional districts must have approximately the same number of people in them (“one man, one vote”). But this leaves a state legislature free to draw the district boundaries in a way that favors one party over the other. Take Illinois, a state that is entitled to have 18 Representatives in Congress (plus of course two Senators, but Senators are elected statewide, so the issue of gerrymandering does not arise for them). Illinois's eighteen congressional districts have virtually identical populations, as required by the “one man, one vote” rule. The City of Chicago is strongly Democratic, but the suburbs tend to be Republican. If the Republicans controlled the Illinois legislature (they don’t), they could, without altering the population size of any district, redraw district boundaries in the Chicago area either to pack the city residents into as few districts as possible in order to minimize the number of districts that would elect a Democratic Representative, or to spread them out into as many districts as possible, where they would be in a minority and so wouldn’t elect any Representatives. Or the legislative majority could combine these tactics: compress as many city residents as possible into a few districts, and place the others in districts in which they would be outnumbered by Republican suburbanites. For a real-world example, an article called “The Great Gerrymander of 2012,” by Sam Wang, www.nytimes.com/2013/02/03/opinion/sunday/the-great-gerrymander-of-2012.html?pagewanted=all&_r=0 (Feb. 2, 2013), points out that “in the seven states where Republicans redrew the districts [in advance of the 2012 national elections], 16.7 million votes were cast for Republicans and 16.4 million votes were cast for Democrats. This elected 73 Republicans and 34 Democrats”—a much higher ratio of Republican to Democrat Representatives than of Republican to Democratic voters. In Ohio for example Republicans won 75 percent of the House seats with 51 percent of the votes. In Maryland and Illinois, where the legislatures were controlled by the Democrats, the figures were approximately reversed. In California, where the legislature had turned redistricting over to a nonpartisan commission, there was no significant discrepancy between the two percentages.
It seems hard to square the results of partisan gerrymandering with “one man, one vote.” It’s true that even in the absence of such gerrymandering, a person who belongs to a minority party in a district shouldn’t, from the standpoint of efficacy, bother to vote in a House race, because his vote will have no effect on who is elected to be the Representative from that district. But the minority voter’s political impotence is attributable to majority preference, a result implied by democratic political theory, while in the 2012 election Democratic voters were in the majority in some states in which, nevertheless, more Republicans than Democrats were elected to the House, and vice versa, a result brought about by partisan gerrymandering and in tension with democratic political theory.
Theory apart, partisan gerrymandering is objectionable because by creating safe congressional districts and thereby reducing political competition it reduces compromise in the House of Representatives. This is true with both “packing” and “spreading” the opposition voters. If the result of “packing” those voters is to create say a solidly Democratic district, the Representative will have no incentive to appeal to Republican voters in the district; there are few of them; he doesn’t need them; and for him to try to attract some of that small number might anger his core constituents. If the result of spreading Democratic voters is to create solidly Republican districts, the Representatives of those districts will similarly have little incentive to try to appeal to Democratic voters. The result is political gerrymandering is thus increased political polarization in the House of Representatives—which has been observed.
I can’t see any social benefits from partisan gerrymandering--nor any difficulty (other political opposition--though that is difficulty enough) in eliminating it, either by requiring that districting be delegated to a nonpartisan commission in each state (the California model) or by programming a computer that will create districts of equal population that are geometrically compact—as near as possible to circular, consistently with the need to equalize the population of the districts and respect certain limitations on perfect symmetry that are imposed by geography: one doesn’t want a district line to divide a house.
The only argument I’ve seen in favor of partisan gerrymandering is that it makes partisan voters happier—their Representative does not have to muffle his extreme views (or those of the voters of his party) in an effort to pick up some votes from members of the other party. So the voters whose candidate wins are happier but the losers—who in the 2012 election at least were more numerous—are unhappier. Gerrymandering that has such consequences is not a utility-maximizing practice.