Supreme Court Allows Arizona to Enforce, for Now, Law Tightening New Voter Registrations

The Supreme Court on Thursday allowed Arizona, at least for now, to toughen some voting requirements, saying that people registering to vote before the coming election must show proof of citizenship.

The decision, issued in a terse, unsigned order, handed a partial victory to Republicans who supported a 2022 Arizona law imposing new restrictions on voting. But the court declined to allow Arizona to put into effect another part of that law, which could have prohibited tens of thousands of voters who are already registered from participating in the presidential election or casting any ballots by mail, unless they provided proof of citizenship.

The decision did not include any legal reasoning, which is common in such emergency applications. But there were signs that the court was divided over the issue, and that Chief Justice John G. Roberts Jr. and Justice Brett M. Kavanaugh may have split their votes between two factions.

The order did not mention either. But it said four justices had wanted to keep the state from enforcing both measures: Justices Sonia Sotomayor, Elena Kagan, Amy Coney Barrett and Ketanji Brown Jackson. It named three as wanting to let the state put both provisions into effect: Justices Clarence Thomas, Samuel A. Alito Jr. and Neil M. Gorsuch.

The mixed decision means Arizonans newly registering to vote for the coming election will have to provide copies of one of several documents, including a birth certificate or a passport, in order to prove their citizenship.

Disputes over voting requirements in Arizona have raged since the 2020 presidential election, when Donald J. Trump narrowly lost the state. Since then, Republican lawmakers have carried out a partisan audit of the election vote count, and Mr. Trump