US District Judge Indira Talwani in Boston issued a temporary restraining order at the behest of Democratic-led states and voting rights groups after the US Supreme Court on Monday issued a ruling that led to the lifting of earlier injunctions blocking Trump's plans to restrict mail-in voting.
That decision led to a frantic effort by dozens of Democratic state attorneys general and voting rights groups including the League of Women Voters to renew their legal fight and secure an order that would prevent the USPS from enforcing a rule that was allowed to take effect on Wednesday.
In Thursday's ruling, Talwani said the rule risked preventing citizens from casting ballots by mail unless states secure the Postal Service's sign-off on the envelopes used for that purpose and upload information on each voter into an electronic portal run by the agency.
The judge said the agency had presented no evidence regarding fraudulent mail-in voting that would necessitate such a rule, which she said likely was unlawful and adopted in violation of the US Constitution, which gives states the authority to administer elections.
"USPS's interest in correcting an unsubstantiated problem through likely unconstitutional means is dwarfed by the overwhelming risk of pervasive disenfranchisement of citizens who need access to mail ballots in order to vote," she wrote.
The restraining order Talwani issued will remain in place while she considers whether to issue a longer-term preliminary injunction blocking the rule. The judge, an appointee of Democratic president Barack Obama, plans to consider whether to do so during a September 3 hearing.
Under the rule, states must supply the USPS with lists of mail ballot recipients, and all outbound and return ballot envelopes must bear unique barcodes.
The White House and USPS did not immediately respond to requests for comment.
The USPS, under the rule, may refuse to deliver ballots that do not comply with the new standards or are associated with voters who do not appear on the lists.
It issued the rule to implement an executive order the Republican president signed in March after years of Trump calling for tighter rules on voting by mail and pushing the false claim that his 2020 presidential election defeat to Democrat Joe Biden was the result of widespread voter fraud.
All 50 states allow for some form of mail-in voting, with 29 allowing voters to ask to cast ballots that way without providing a reason and eight conducting their elections entirely by mail.
During the 2024 election, the USPS says it processed nearly 100 million ballots, and about 30 per cent of voters nationwide cast ballots by mail, according to the states.
They argue the new federal restrictions risk disenfranchising voters and would unduly burden states in the weeks running up to the election, forcing them to buy new envelopes and equipment, establish new systems and train staff.
The plaintiffs argue the USPS lacks authority to issue the rule and by issuing it usurped the authority states and Congress were given under the US Constitution to regulate elections. They contend the rule also undermines the USPS' role as a neutral mail carrier and violates federal laws protecting voters' rights.
