Aside from whether ranked choice voting (RCV) is a good idea as policy or not, the question is sometimes raised whether it’s consistent with the U.S. Constitution. An October analysis by Jimmy Balser for the Congressional Research Service helps make clear that the answer is yes. So long as they follow other applicable provisions of the Constitution and federal law, states and cities may adopt RCV without fear of violating the federal constitution. On the other hand, courts may find RCV inconsistent with the language of at least some state constitutions, and that question has to be sorted out state by state.

in the 2011 case of Dudum v. Arntz, an ideologically diverse panel of the Ninth Circuit upheld San Francisco’s RCV law against equal protection, due process, and First Amendment challenges. It “rejected the claim that ranking candidates somehow dilutes votes,” notes Balser, “since the ability to rank preferences sequentially does not affect the ultimate weight accorded any vote cast in an election.” It likewise dismissed arguments that ranking imposes any improper burden on the right to vote. And it upheld a particular San Francisco rule according voters only three rank choices, even if more than three candidates were on the ballot, against a claim that this somehow disenfranchised voters none of whose three choices won.