In Rucho v. Common Cause, decided June 27, 2019, the Supreme Court ruled 5–4 that federal courts cannot hear claims that a state’s electoral map is an unconstitutional partisan gerrymander. Chief Justice John Roberts, writing for the majority, concluded that no “judicially manageable standard” exists for deciding when partisan line-drawing crosses a constitutional line. The practical effect is blunt: no matter how aggressively a state legislature rigs its map to entrench one party, voters who feel cheated cannot ask a federal judge to intervene. Their remedies now live in state courts, state constitutions, independent redistricting commissions, and Congress.
What the Court Held
The majority opinion, joined by Justices Thomas, Alito, Gorsuch, and Kavanaugh, declared partisan gerrymandering claims “political questions beyond the reach of the federal courts.” That is a term of art. Under Article III, federal judges can only decide real “cases and controversies,” and part of what makes a dispute justiciable is the existence of a legal framework capable of producing consistent, principled answers rather than ad hoc policy calls. When a dispute lacks that framework, courts label it a political question and decline to hear it. The remedy, if any, has to come from elected officials or the political process itself.
Roberts leaned on the Elections Clause of Article I, Section 4, which assigns the regulation of federal elections to state legislatures with Congress holding override power. In the majority’s reading, the Constitution had already placed this question outside the judiciary.
The ruling closed a door the Court had left cracked open for fifteen years. In Vieth v. Jubelirer (2004), Justice Kennedy had refused to declare partisan gerrymandering claims non-justiciable, writing that “a workable standard for measuring a gerrymander’s burden on representational rights has not yet emerged” but “does not mean that none will emerge in the future.” Rucho concluded that none had, and none would.
The North Carolina and Maryland Maps
Two consolidated challenges brought the question to a head. North Carolina’s Republican-controlled legislature drew a 2016 congressional map that produced Republican wins in 10 of 13 seats despite a roughly even statewide vote. The mapmakers made no secret of their partisan intent, and a federal district court struck the map down.
Maryland worked in the opposite direction. After the 2010 census, the Democratic-controlled legislature redrew the Sixth Congressional District to flip it from Republican to Democratic, moving hundreds of thousands of voters in or out using political data. Republican voters sued, arguing the state had retaliated against them for their political views. A separate federal court agreed.
The plaintiffs raised First Amendment and Fourteenth Amendment Equal Protection claims. Both lower courts had ruled for the challengers. The Supreme Court reversed both.
Why the Majority Found No Manageable Standard
Roberts framed the core difficulty carefully. The problem was not proving that a legislature engaged in partisan gerrymandering. In the North Carolina case, everyone agreed that was the goal. The “central problem” was “determining when political gerrymandering has gone too far.”
The Constitution, the majority reasoned, supplies no benchmark for partisan fairness in redistricting. Some degree of partisan consideration has always been part of American map-drawing. And people define a fair map in incompatible ways. Some think fairness means proportional representation. Others think it means competitive districts. Others still think it means preserving communities of interest or respecting county lines. Choosing among “these different visions of fairness,” Roberts wrote, “poses basic questions that are political, not legal.”
The majority also rejected the fallback idea that courts could police only the most extreme cases. Without a constitutional principle defining “too far,” any outlier standard would still require judges to draw an arbitrary line. Losing parties would challenge maps every cycle, and federal judges would end up “reallocating political power between the two major political parties, with no plausible grant of authority in the Constitution, and no legal standards to limit and direct their decisions.”
The Mathematical Tests the Court Rejected
Challengers came armed with quantitative measures designed to give courts an objective benchmark. The most prominent was the efficiency gap, which counts votes “wasted” by each party. A vote is wasted if it is cast for a losing candidate or if it exceeds the number a winning candidate needed. When one party wastes far more votes than the other across a statewide map, the gap suggests the map was drawn to convert votes into seats more efficiently for the mapmakers’ side. Scholars who developed the metric proposed concrete thresholds: an efficiency gap of two or more seats for congressional plans, or 8 percent or more for state legislative plans, would trigger a presumption of unconstitutionality.
Other proposed tools included the mean-median difference, which compares a party’s average vote share across districts to its median district performance, and computer-simulated “ensemble” analyses that generate thousands of alternative maps to see whether the enacted plan is a statistical outlier.
The majority rejected all of them. Roberts argued they lacked a constitutional anchor. The efficiency gap assumes a party is entitled to translate votes into seats at a particular rate, but nothing in the Constitution guarantees proportional representation. Adopting any mathematical threshold, the Court warned, would invite challenges to every map in the country and turn federal courts into permanent redistricting oversight boards. Clever social science, in the majority’s view, is not constitutional law.
Justice Kagan’s Dissent
Justice Kagan, joined by Justices Ginsburg, Breyer, and Sotomayor, called the decision “a tragically wrong turn.” She argued that manageable standards were not only available but had already been applied by lower courts.
Kagan endorsed a three-part test built on intent, effects, and causation. First, challengers had to prove the mapmakers’ predominant purpose was to entrench their party by diluting the opposing party’s votes. Second, they had to show the map actually achieved that goal by substantially diluting the targeted group’s voting power. Third, if challengers made both showings, the burden shifted to the state to offer a legitimate, non-partisan justification for the district lines. That framework, Kagan wrote, was no more complex than standards the Court routinely applies elsewhere in constitutional law.
Her sharpest criticism was that the maps in both states were drawn with open partisan intent, produced lopsided results, and could not be explained by any neutral principle. The Court’s refusal to act, she said, was a choice, not a constitutional command. In her view, the majority was “abandoning its duty to declare the law” at the moment that duty mattered most.
Where Voters Can Still Turn: State Courts
Rucho closed the federal courthouse door but explicitly left state courts open. The majority acknowledged that state constitutions might provide independent grounds for challenging partisan gerrymanders. Litigants tested the theory immediately, and the results vary sharply from state to state.
Pennsylvania moved first. In 2018, the Pennsylvania Supreme Court struck down the state’s congressional map under the Pennsylvania Constitution’s Free and Equal Elections Clause, which requires that “elections shall be free and equal.” North Carolina’s state courts followed in 2019, using a similar free elections provision to invalidate state legislative maps. State constitutional text, these rulings showed, could do what the federal Constitution, as interpreted in Rucho, would not.
The state-court route was then reinforced by Moore v. Harper (2023). The Supreme Court rejected the “independent state legislature” theory, which would have insulated state legislatures from state court review when they set federal election rules. The Court held that “the Elections Clause does not insulate state legislatures from the ordinary exercise of state judicial review” and that legislatures remain “created and bound by” their state constitutions when they draw maps.
The limitation is straightforward. Not every state constitution contains a free elections clause, and not every state supreme court reads its constitution to reach partisan gerrymandering. Voters in states with strong protections and receptive courts have a real remedy. Voters in states without them do not.
Where Voters Can Still Turn: Commissions and Congress
The other avenue runs through the political process the Rucho majority pointed to. Fifteen states now use commissions with primary responsibility for drawing state legislative maps, including Arizona, California, Colorado, Michigan, and Virginia. Six more states have advisory commissions, and five have backup commissions that step in if the legislature deadlocks.
Research suggests independent commissions matter. A study of U.S. House elections from 1982 to 2018 found that commission-drawn districts were 2.25 times more likely to produce competitive elections than those drawn by legislatures, and commissions decreased incumbent-party wins by roughly 52 percent compared to legislative redistricting. In California, competitive congressional districts rose from about 5 percent before the state adopted an independent commission to about 15 percent afterward. Commissions staffed by politicians or chosen by legislative leaders showed no statistically significant improvement over legislature-drawn maps.
At the federal level, Congress has broad authority under the Elections Clause to set nationwide redistricting rules. The Supreme Court has described that authority as “paramount” and one that “may be exercised at any time, and to any extent which it deems expedient.” The Redistricting Reform Act of 2025 would require every state to establish a 15-member nonpartisan commission, prohibit mid-decade redistricting, and bar the use of political data except to comply with the Voting Rights Act. No such legislation has passed, and the party that benefits from gerrymandering in a given cycle has little incentive to vote for reform.
What Rucho Means for You
Your protection against partisan gerrymandering now depends almost entirely on which state you live in. If your state has a free elections clause and a state supreme court willing to enforce it, or an independent redistricting commission with real authority, you have meaningful safeguards. If your state has neither, the federal Constitution as currently interpreted offers you nothing. Unless Congress acts or the Court reverses itself, the map your state legislature draws is the map you get.