The Supreme Court on Monday ruled that states can continue counting mail-in ballots sent by and received within five days of Election Day, a decision that delivers a significant blow to President Donald Trump's efforts to curtail mail-in voting. The high court, in a 5-4 decision, allowed state voting laws that permit the counting of such ballots to remain in place.

"The election-day statutes say nothing about ballot receipt, and we cannot add to the words Congress chose," Justice Amy Coney Barrett wrote for the majority. She noted that the court does not have the discretion to alter federal election law regarding ballot receipt deadlines.

The case, Watson v. Republican National Committee, centered on a 2024 lawsuit challenging Mississippi's state law that permits the counting of mail-in ballots received up to five days after the election, provided they are postmarked by or before Election Day.

Mississippi is among 14 states, the District of Columbia, and three U.S. territories that currently allow the counting of late-arriving mail-in ballots, as long as they are postmarked by Election Day. The Democratic National Committee filed an amicus brief in support of counting these ballots, emphasizing their widespread use by various demographics, including seniors, voters with disabilities, and military personnel. The DNC argued that the act of voting refers to the voter's choice, not the subsequent administrative process of receiving or counting ballots.

The Supreme Court heard oral arguments in the case in March. The ruling on Monday affirmed the legality of these state-level provisions for mail-in ballot acceptance.