The US Supreme Court is preparing to hear oral arguments in December in RNC v. Mi Familia Vote, a case that will decide whether two Arizona voter-registration laws breach the federal National Voter Registration Act. The laws require proof of US citizenship at registration and allow removal of noncitizen registrations from electoral rolls within 90 days of an election; a lower appeals court found they amounted to voter suppression, a ruling election-integrity groups are now urging the justices to overturn, warning it could leave states powerless to correct faulty registrations.

In an amicus brief filed on Thursday, the Center for Election Confidence, Restoring Integrity and Trust in Elections, and the Honest Elections Project argued that the Ninth Circuit's interpretation of the National Voter Registration Act's 90-day pre-election restriction on systematic roll purges wrongly extends to bar removal of noncitizens, since non-citizenship is not among the law's listed exceptions covering death, conviction or mental incapacity. They said this could make it "absurd" and effectively impossible to remove ineligible voters, including noncitizens, minors or fictitious entries, once registered, and cited reported registration errors in New Jersey, Illinois and Oregon as evidence states need such a mechanism. Groups such as Restoring Integrity and Trust in Elections and the Center for Election Confidence say they expect the Supreme Court to side with Arizona and reverse the lower court's decision.