During oral arguments in Watson v. Republican National Committee on March 23, 2026, a majority of Supreme Court justices expressed skepticism toward state grace periods allowing mail-in ballots postmarked by Election Day but received later, signaling readiness to rule that federal election law requires receipt by Election Day. This follows the Fifth Circuit's prior decision striking down Mississippi's five-day extension, which the full court upheld in a 10-5 vote denying rehearing. With a ruling expected by late June ahead of 2026 midterm primaries, traders price an 88% implied probability of SCOTUS barring such practices nationwide, affecting 14 states plus D.C., as election officials recently warned of potential disruptions.