The Supreme Court has dealt President Trump a major election-year setback by refusing to let his administration enforce new security rules for mail ballots ahead of the 2026 midterms.
In a decision Monday night, the justices denied the administration’s emergency request to pause a nationwide injunction against the rule, leaving the updated U.S. Postal Service system blocked while states continue mailing ballots for the November election.
The Court’s order stated that the government was unlikely to prevail in its challenge to the preliminary injunction and that the equities did not favor emergency relief.
Justice Brett Kavanaugh explained his vote in a separate opinion, noting there is at least a fair prospect that the final rule falls within the Postal Service’s statutory authority. However, he concluded that applying it during the 2026 elections would be arbitrary and capricious because state and local officials had not been given sufficient time to implement the system reasonably.
Kavanaugh emphasized that the administration came to the Court too late to install the new requirements during voting already underway.
Justices Samuel Alito and Clarence Thomas were the only members of the Court to publicly dissent. Alito argued that the Postal Service has broad legal authority to regulate the mail, that challengers were unlikely to succeed, and that the government had satisfied the requirements for a stay.
The blocked rule stems from President Trump’s March executive order on citizenship verification and federal election integrity. The White House directive required federal agencies to create state citizenship lists using Department of Homeland Security, Social Security Administration records, and other federal data. These lists were meant to identify confirmed American citizens at least 18 years old who reside in the state.
The order mandated that such lists be updated and sent to state election officials at least 60 days before elections and included procedures for record inspection and correction. For mail ballots, it called for secure envelope identifiers, unique Intelligent Mail barcodes, and a system connecting each ballot mailing to an enrolled voter.
The Postal Service finalized the rule in August, requiring federal ballot mail to use envelopes with the Election Mail logo, high-speed processing compatible designs, and specialized barcodes. Election offices also had to submit their envelope designs for review and upload voter information to a federal portal. Ballots failing these standards could be rejected and returned for correction.
The final rule stated that state officials would continue determining ballot eligibility and that the USPS would not rewrite voter lists. The security mechanism was designed to condition access to the federal mailstream on the new requirements.
The Court’s ruling does not legalize noncitizen voting, which remains a federal crime. Its immediate effect is to remove the new federal verification and traceability layer President Trump sought for mailed ballots this November.
