The League of Women Voters of the United States joined with the League of Women Voters of Kansas and the League of Women Voters of Arizona to file a brief on the merits of Kobach v. EAC in U.S. District Court. The Leagues won a successful bid to intervene in this case after arguing that the decision of the states of Arizona and Kansas to require proof of citizenship when registering to vote, impacts the work that the League does to register voters.