The US Supreme Court has rejected President Donald Trump’s attempt to introduce new restrictions on voting by mail ahead of November’s midterm elections, delivering a setback to the White House.
The justices upheld a federal judge’s order temporarily preventing the US Postal Service from implementing new requirements for processing and delivering postal ballots.
However, the ruling may not be the final decision in the case. Conservative Justice Brett Kavanaugh joined the ruling but suggested he could ultimately support Trump’s position as the wider legal challenge continues.
Kavanaugh wrote that there was “at least a fair prospect” that the final rule could fall within the Postal Service’s legal authority. However, he argued that introducing the measures during the 2026 elections could be considered “arbitrary and capricious.”
Justices Samuel Alito and Clarence Thomas dissented, arguing that the challenge against Trump’s order was unlikely to succeed in the long term. They said the Postal Service has broad authority to regulate the mail.
The White House did not immediately comment on the decision.
Trump has repeatedly sought to restrict voting by mail since returning to the White House. He has long argued, without evidence, that mail voting creates opportunities for electoral fraud and could allow non-citizens to cast ballots.
In a March executive order, Trump directed the USPS to introduce new rules affecting mail-in and absentee ballots. Among the measures was a requirement that ballots only be transmitted for individuals enrolled on state-specific voter lists. The order also called for the development of envelopes containing bar codes.
Trump argued that the measures were necessary to protect the integrity of elections. His administration maintained in court filings that the rules were constitutional, arguing that states could not rely on the federal postal system for elections while claiming that election-related mail was exempt from USPS regulations.
Twenty-three states and Washington DC challenged the executive order in court.
The postal workers’ union warned that there would not be enough time to train clerks to implement the new procedures before the election. A national security group also raised concerns about how the proposed rules could affect military personnel voting from overseas.
On September 4, Boston-based federal Judge Indira Talwani issued an injunction blocking Trump’s order. She ruled that introducing the requirements so close to the November elections could disenfranchise voters.
A US appeals court later declined to suspend Talwani’s order, while another federal judge, Carl Nichols, also ruled against the administration’s order on Sunday.
The legal dispute comes as some states have already begun distributing mail-in ballots for the midterm elections, which will determine which political party controls Congress.
The Supreme Court decision marks another setback for Trump over mail voting. In June, the justices ruled that states could count ballots postmarked by election day, rejecting an effort by the Trump administration to prevent votes arriving after polling day from being counted.
Mail voting remains a major part of the US electoral system. Around 30% of voters cast their ballots by mail during the 2024 general election, according to the US Election Assistance Commission, an independent federal agency.
Trump has repeatedly claimed that widespread fraud caused his defeat in the 2020 presidential election, although those claims have never been substantiated.
With the 2026 midterm elections approaching, the dispute over mail voting is expected to remain a significant political and legal issue as states, election officials and the federal government continue to debate the extent of presidential and postal authority over the voting process.
