A federal appellate court grappled Tuesday with Mississippi’s mail-in ballot law, which allows ballots to be counted up to five days after Election Day if they were postmarked on time.

A three-judge panel of the 5th U.S. Circuit Court of Appeals heard from the state Republican Party, which sued Mississippi officials in January and asking for the state law to be enjoined. The GOP argues that Congress set one federal Election Day.

Judges James Ho, Stuart Kyle Duncan and Andrew Oldham, all Trump appointees, questioned how a ruling could impact November’s elections.

Conor Woodfin, representing the Mississippi Republican Party, told the panel they want this case resolved before Nov. 5, insisting that history supports the claim of a federal Election Day.

“The meaning of Election Day is not up to the subjective views of each state. Instead, text and history tell us what those words mean and historical practice is especially important,” Mr. Woodfin said.

Scott G. Stewart, representing the Mississippi secretary of state defending the law, pushed back, saying all states are allowed to set their own policies.

“This is an area where the states are generally first movers,” Mr. Stewart said. “States are free to do this.”

The state GOP is urging the panel to rule quickly.

The Republican Party’s original complaint alleged that “Mississippi contravenes those federal laws by counting mail-in ballots that are received up to five business days after Election Day.”

“Mississippi effectively extends Mississippi’s federal election past the Election Day established by Congress. The result of Mississippi’s violation of federal law is that timely, valid ballots are diluted by untimely, invalid ballots, which violates the rights of candidates, campaigns, and voters under federal law,” read the complaint, filed Jan. 26, before the U.S. District Court for the Southern District of Mississippi.

The district court granted the state officials’ motion for summary judgment, and the RNC appealed to the 5th Circuit in New Orleans.

The case has the potential impact of curtailing voting laws in other states.

If the panel were to rule against Mississippi’s law, ballots could not be counted past Election Day, which is the standard in more than 18 states and territories, according to the National Conference of State Legislatures.

Mississippi is not a battleground state, but Nevada and Ohio are, and both have similar mail-in ballot laws.

Maryland, where there’s a close race for a U.S. Senate seat, allows mail-in ballots to be counted for up to 10 days so long as they were postmarked on time, according to NCSL.

• Alex Swoyer can be reached at aswoyer@washingtontimes.com.