The fight over mail-in ballots has moved from state legislatures to the nation’s highest court, and the stakes could not be higher. In Watson v. Republican National Committee, the justices are being asked whether federal law silently forbids states from counting ballots that arrive after Election Day, even if they were mailed on time. Dozens of states, and millions of voters who rely on mail, could see their rules — and expectations — overturned in one opinion.

The Court has already signaled it will not stay on the sidelines. In Bost v. Illinois State Board of Elections, a 7–2 majority ruled that federal candidates themselves can challenge how elections are run, inviting a wave of lawsuits every time a race is close. Together, these cases point to a future where election rules are no longer quiet background details, but the main battlefield on which American democracy is fought.