By Iuri Macedo Piovezan, M.A.
An Arizona voter can be eligible to vote for Congress but not for the Arizona Legislature. That unusual result is not necessarily because the voter satisfies different substantive citizenship qualifications for the two elections. Instead, it can turn on whether Arizona possesses documentary proof of the voter’s citizenship. Under Arizona’s current voter-registration system, a registrant who attests to U.S. citizenship but does not provide documentary proof—and whose citizenship cannot otherwise be verified through state records—may be classified as a “federal-only” voter. That voter may participate in federal elections but not state and local elections unless documentary proof is subsequently provided. Arizona election officials currently recognize documents including certain Arizona driver’s licenses, passports, birth certificates, naturalization documents, and specified tribal records as proof of citizenship. As of January 2, 2026, Arizona reported 44,627 federal-only registrants, although that total also includes voters lacking documented proof of residency rather than citizenship alone.
The constitutional and statutory tensions underlying this system will soon return to the Supreme Court. On June 29, 2026, the Court granted certiorari in Republican National Committee v. Mi Familia Vota, and oral argument is scheduled for December 8. Although the litigation involves several provisions of Arizona election law, the dispute raises a basic federalism question: when a state determines who is qualified to vote but Congress regulates how voters register for federal elections, who controls the evidence that an applicant must provide?
The controversy has roots extending well beyond the present litigation. In 2004, Arizona voters adopted which required documentary proof of citizenship for voter registration. That requirement eventually reached the Supreme Court in Arizona v. Inter Tribal Council of Arizona, Inc. In 2013, the Court held that the National Voter Registration Act (“NVRA”) preempted Arizona’s attempt to require applicants using the federal voter-registration form to submit documentary proof of citizenship. The NVRA requires states to “accept and use” the federally prescribed mail registration form for federal elections. The federal form requires an applicant to attest to citizenship under penalty of perjury, but it does not itself require documentary proof of citizenship. Inter Tribal Council therefore held that Arizona could not demand additional citizenship documentation from a Federal Form applicant as a condition of federal registration.
But Inter Tribal Council did not eliminate the underlying division of constitutional authority. The Court emphasized that determining voter qualifications and regulating the mechanics of federal elections are related but distinct powers. States retain authority to prescribe voter qualifications, subject to other constitutional limitations. At the same time, the Elections Clause gives state legislatures initial authority over the of congressional elections while expressly permitting Congress to “make or alter” those regulations. The Inter Tribal Council Court characterized voter-registration procedures as falling within that “[m]anner” authority and therefore subject to congressional regulation. The distinction sounds relatively clean in theory. Arizona’s experience demonstrates how quickly it becomes complicated in practice.
The Arizona Legislature revisited the issue in 2022 through H.B. 2492. Among other provisions, the legislation sought to require additional proof from applicants using Arizona’s state registration form and imposed restrictions affecting federal-only voters. The resulting litigation ultimately reached the Ninth Circuit in Mi Familia Vota v. Petersen. The court concluded, among other things, that the NVRA preempted Arizona’s requirement that state-form applicants provide documentary proof of citizenship to register only for federal elections. The majority reasoned that although Arizona may use its own state voter-registration form, the requirements imposed on applicants using that form to register for federal elections remain subject to the NVRA’s restrictions. Arizona and other challengers dispute that interpretation. Arizona’s current Supreme Court brief argues that the Ninth Circuit read the NVRA too broadly and that the state retains authority to require documentary proof when an applicant chooses Arizona’s own registration form.
That disagreement exposes the difficult line the Supreme Court must draw. Arizona has an interest in determining whether applicants satisfy its citizenship qualification. Federal law, however, regulates registration for federal elections and limits the information that registration forms may require. The RNC and supporting parties argue, in substance, that requiring proof of an existing qualification is part of Arizona’s authority to determine and enforce voter eligibility. The opposing parties prevailed below on the argument that Congress has already prescribed requirements governing registration for federal elections and that Arizona cannot impose additional documentary requirements on applicants using its state-created form beyond those permitted by the NVRA. The dispute therefore concerns more than whether citizenship may be required to vote—federal and Arizona law both require citizenship. It concerns which sovereign controls the procedure used to establish that qualification when a person registers for a federal election.
The practical consequence is Arizona’s increasingly significant category of federal-only voters. A person whose citizenship has not been documented to Arizona’s satisfaction is not necessarily a person who is not a citizen. Arizona itself distinguishes the two: federal-only registrants must attest to U.S. citizenship, and only citizens are legally eligible to register. What is missing is documentary confirmation sufficient for full-ballot status, which is a significant distinction. Characterizing the litigation simply as a dispute over whether noncitizens can vote obscures the actual legal question before the courts. The conflict is principally about what evidence an otherwise eligible applicant must furnish, which governmental entity may require it, and what consequences may follow when the applicant does not.
The Supreme Court’s decision may also clarify how far Inter Tribal Council extends beyond the Federal Form itself. The RNC litigation asks the Court to address Arizona’s requirements involving the state-created registration form, while related disputes concern restrictions on federal-only voters’ access to voting by mail. One argument advanced in the litigation is that Inter Tribal Council merely guarantees that the Federal Form can accomplish registration; it does not necessarily determine every rule governing how a registered voter subsequently casts a ballot. treats those restrictions as incompatible with the federal registration regime and the protections Congress attached to it. The distinction between regulating registration and regulating the subsequent method of voting could therefore prove as consequential as the dispute over documentary proof itself.
Arizona’s system presents an unusual illustration of American election federalism. The same citizen, living at the same address and registering at the same time, can occupy different legal positions depending on which election appears on the ballot and what documentation election officials possess. Whether federal law requires that result, prohibits portions of it, or leaves more discretion to Arizona is now before the Supreme Court. Whatever the Court ultimately decides, RNC v. Mi Familia Vota will require it to confront a recurring difficulty in election law: voter qualifications may belong principally to the states, while the machinery through which Americans establish those qualifications for federal elections does not belong to the states alone.
Iuri Macedo Piovezan is a J.D. candidate, Class of 2027, at Rutgers Law School and a member of the Rutgers University Law Review. He holds a master’s degree in political science from Villanova University, where he graduated with distinction in 2024. One can see his publications on populism and polarization in the Georgetown Public Policy Review, Penn Political Review, Carolina Political Review, the São Paulo Magazine, among others.
