Mississippi's law counts mail-in ballots sent by some voters if they were postmarked on or before, and received up to five business days after, Election Day.

The U.S. Supreme Court is to hear Monday a legal case that could have ramifications on mail-in balloting deadlines in the upcoming mid-term elections.

The case could impact laws in more than a dozen states.

The U.S. Supreme Court will hear arguments Monday about mail-in voting in Mississippi and whether the state's ballot deadline is valid.

Conservative justices appeared ready to strike down so-called “grace periods” for election officials to count mail-in ballots after Election Day.

Mississippi's law counts mail-in ballots sent by some voters if they were postmarked on or before, and received up to five business days after, Election Day.

The Supreme Court's conservative majority seemed skeptical of late-arriving ballots. The case could lead to stricter rules in this year's midterm elections.