Rucho v. Common Cause

Majority reasoning

The majority held that partisan gerrymandering claims ask courts to decide how much partisan advantage is "too much," a question with no discoverable and manageable legal standard because the Constitution does not require proportional representation between parties. It reasoned that any judicial test would require judges to pick among competing, non-legal visions of "fairness"—proportionality, competitiveness, or adherence to traditional criteria—none of which the Constitution supplies grounds for choosing. The Court rejected the dissent's proposed standard of comparing a map to a median of computer-generated alternative maps, reasoning that using a state's own self-selected districting criteria as a baseline is itself arbitrary and would still leave courts guessing where a permissible deviation becomes impermissible. The majority also found that Article I's Elections Clause assigns districting power to state legislatures, checked by Congress, with no historical indication the Framers intended a role for federal courts, and it noted that the First Amendment and Equal Protection Clause frameworks used by the lower courts effectively barred any partisan consideration in districting, contrary to precedent allowing some political line-drawing. It concluded that avenues for addressing gerrymandering remain open through Congress, state constitutions, and independent redistricting commissions, just not through federal courts.

Dissent reasoning

Justice Kagan, joined by Justices Ginsburg, Breyer, and Sotomayor, argued that the North Carolina and Maryland maps inflicted real, documented constitutional harm by deliberately diluting the votes of citizens based on party affiliation, violating the Equal Protection Clause and the First Amendment's protection of political association. The dissent argued that lower courts had already developed a manageable, neutral three-part standard—requiring proof of predominant partisan intent, substantial vote-dilution effect measured against computer-generated alternative maps built from the state's own non-partisan criteria, and lack of a legitimate justification—that does not require courts to invent their own vision of fairness. It contended the majority mischaracterized this approach as demanding proportional representation, when in fact it merely measured how far a map departed from what the state's own political geography and traditional districting criteria would have produced absent partisan manipulation. The dissent warned that leaving these gerrymanders unchecked lets politicians entrench themselves against the will of voters, undermines the constitutional principle that voters choose their representatives rather than the reverse, and that the majority's suggested alternatives—congressional legislation, ballot initiatives, and state courts—offer no realistic remedy since legislators benefiting from gerrymandering are unlikely to change it and most states lack ballot initiative mechanisms.