WASHINGTON – The Supreme Court will hear arguments on Oct 8 in a case dealing with rules allowing mail-in ballots in Illinois to be counted even if received after Election Day, a practice permitted in many Democratic-led states that has been repeatedly challenged by Republicans.

At issue in the case is the narrow question of whether a federal elected official can sue to stop a state from counting such ballots.

Under Illinois law, ballots postmarked by Election Day are counted if they are received up to 14 days later.

Representative Mike Bost, a six-term Republican who represents a district in downstate Illinois, and two electors filed a lawsuit in May 2022 arguing that the late-ballot rule is superseded by laws enacted by Congress setting the time for federal elections.

The lawsuit was one of several challenges brought by allies of President Donald Trump to question the guidelines around mail-in ballots, which he has long attacked and falsely blamed for his 2020 election loss as more people voted by mail during the pandemic.

It is also the first of several voting rights and election-related disputes the justices are scheduled to hear this term, setting up an important year for the court and the mechanics of democracy.

Although the question presented in Mr Bost’s case is narrow, a victory for him could clear the way for other such challenges, including a Mississippi case pending before the court testing whether a five-day postelection grace period for late mail-in ballots violates federal law.

In July 2023, a federal judge dismissed the case, finding that Mr Bost had failed to show he had standing to sue, a threshold legal requirement that Mr Bost demonstrate he suffered a direct injury from the law.

Mr Bost asserted that he had suffered a financial cost because he had to run his campaign for two weeks after the election to monitor ballot receipts and counting. He also argued that, as a candidate, he had a particular interest in an accurate tally of votes.

A divided panel of three j...