Millions of Americans register to vote by checking a box that says “I am a U.S. citizen.” Arizona wants more than a box. It wants a copy of your birth certificate, passport, or naturalization papers before it will let you register using the state’s own form, and it wants the power to strip people from the voter rolls close to Election Day if officials suspect they aren’t citizens. Whether either of those things is legal under federal law is now before the U.S. Supreme Court in Republican National Committee v. Mi Familia Vota.

The case grew out of a long fight over two Arizona laws passed in 2022, House Bills 2492 and 2243, part of a wave of election-law changes states made after the 2020 election. HB 2492 said that if someone registers using Arizona’s own state form and doesn’t attach documentary proof of citizenship, officials must reject the application outright. HB 2243 told county recorders to periodically check government databases for signs that a registered voter might not be a citizen, and to cancel those registrations, even within 90 days of a federal election.

To understand why that’s complicated, rewind to 2013. In Arizona v. Inter Tribal Council of Arizona, the Supreme Court ruled that a federal law called the National Voter Registration Act (NVRA) requires every state to accept a standard federal voter-registration form, which only asks people to swear they’re citizens under penalty of perjury, no documents required. Arizona responded by creating a second class of voters: people who register with the federal form and no proof of citizenship become “federal-only” voters, able to vote for president and Congress but not for governor, mayor, or local ballot measures.

Then in 2018, voting-rights groups sued Arizona’s Secretary of State over the unequal treatment of the state and federal forms. That case ended in a consent decree, essentially a settlement approved by a federal judge, in which the Secretary agreed that people using the state form without proof of citizenship would also become federal-only voters rather than get rejected outright. That was the practice until HB 2492 tried to reverse it in 2022, ordering officials to throw out incomplete state-form applications entirely.

A coalition including Mi Familia Vota, Voto Latino, several Arizona tribal nations, and the Democratic National Committee sued to block the new law. After a ten-day trial, a federal district court sided with them, ruling that both the 2018 consent decree and the NVRA barred Arizona from rejecting state-form applicants over missing citizenship paperwork, and that the NVRA’s 90-day rule blocked large-scale removals of suspected noncitizens close to an election. A divided Ninth Circuit panel mostly upheld that ruling in 2025, over a lengthy dissent from Judge Patrick Bumatay, who called the majority’s approach unprecedented. Eleven judges later objected when the full appeals court declined to rehear the case.

Notably, Arizona itself did not appeal. It was the Republican National Committee, which had intervened to defend the law, along with the leaders of the Arizona legislature in a separate but related petition, who asked the Supreme Court to step in. The justices agreed on June 29, 2026, to hear the RNC’s case alongside two related petitions raising overlapping issues.

The Court will weigh two questions. First, do the NVRA or that 2018 consent decree stop Arizona from rejecting state-form registrations that lack documentary proof of citizenship? Second, does the NVRA prevent Arizona from running a program that cancels suspected noncitizens’ registrations within 90 days of a federal election?

Underneath the technical language sits a bigger argument about federal power over state elections. The RNC says states have near-total authority to decide who’s qualified to vote, and that the NVRA’s requirement that registration forms ask only for “necessary” information should be read broadly: proof of citizenship is necessary, in the RNC’s view, because it directly verifies the one qualification every state demands. The RNC also argues that a consent decree signed by one Secretary of State in 2018 can’t permanently tie the hands of a legislature that later passes new law, warning that letting old settlements override future statutes raises real separation-of-powers concerns. On the 90-day question, the RNC contends noncitizens were never eligible to register in the first place, so they don’t count as the kind of “registrant” the NVRA shields from removal, and that reading the statute otherwise would make it nearly impossible to ever remove an improperly registered noncitizen. The RNC also points to a split among federal appeals courts on this exact point: the Sixth Circuit has allowed removal of never-eligible voters near an election, while the Eleventh Circuit, and now the Ninth, have gone the other way.

Mi Familia Vota and its co-respondents see it differently. They argue “necessary” should be read narrowly, to mean essential or indispensable, and that Arizona already gets a citizenship proof through the checkbox on its own form, the same kind of proof federal election officials have long accepted as sufficient on the federal form. Since identical statutory language governs both forms, they argue, Arizona can’t demand more from one group of applicants than the other without real justification. On the consent decree, they point out that federal court judgments don’t expire just because a legislature later dislikes them. If a party wants out of a decree, the normal path is asking the court that issued it to modify or lift it, something no one in this case ever did. They also stress that the dispute is unusually Arizona-specific: no other state combines a two-tier registration system with an outright rejection of incomplete state-form applications, so they argue there’s no real conflict among lower courts for the Supreme Court to resolve.

A related fight, raised in the companion Petersen case, asks whether Arizona can bar federal-only voters, and only them, from voting by mail, since roughly nine in ten Arizonans vote that way. Mi Familia Vota argues that penalizing federal-form registrants for using the very registration method Congress protected would undercut the whole point of the NVRA.

When the arguments happen, expect time spent on what “necessary” means in this context, since much of the case turns on whether Arizona’s proof-of-citizenship rule is genuinely required to verify eligibility or is simply one option among several reasonable ones. Watch for questions about the reach of consent decrees, too: can a settlement signed by one executive-branch official in one administration bind an entire state legislature indefinitely, or does that hand too much lawmaking power to whoever happens to hold an office when a lawsuit settles? The justices will also have to work through careful statutory parsing on the 90-day removal question, looking at how the NVRA’s language moves a person from “applicant” to “registrant” to “eligible” or “ineligible voter,” and deciding whether that chain leaves room for noncitizens at all. Because Arizona’s proof-of-citizenship fight has already reached the Court twice before on emergency applications, including once in this very case ahead of the 2024 election, justices may also ask whether this is finally the right case to settle the underlying legal questions for good, rather than revisiting them in a rush the next time an election approaches.

For young voters, especially first-time registrants, this case is very relatable. Several organizations on the respondents’ side, including Mi Familia Vota, Voto Latino, and the Arizona Students’ Association, exist specifically to register young and first-time voters, alongside tribal nations like the Tohono O’odham Nation and the San Carlos Apache Tribe, whose members have long faced extra hurdles proving residency and identity under state law. How the Court rules could shape which registration form actually gets a person a full ballot in Arizona, and it may influence how other states approach similar proof-of-citizenship proposals, at a moment when documentary proof-of-citizenship requirements are also being debated in Congress.

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