Supreme Court lets federal candidates sue over late-counted mail ballots

The Supreme Court on Tuesday handed federal candidates a powerful new tool to challenge how elections are run, ruling 7-2 that an Illinois congressman may sue over a state law that allows mail ballots to be counted for two weeks after Election Day.

What the court decided

The decision in Bost v. Illinois State Board of Elections does not determine whether Illinois’ 14-day mail ballot window is lawful. Instead, the court held that Rep. Michael Bost, a Republican who represents southern Illinois, has the right to bring that challenge in federal court—a ruling election lawyers say could open the door to a surge of candidate-driven lawsuits over voting rules nationwide.

“As a candidate for office, Congressman Bost has standing to challenge the rules that govern the counting of votes in his election,” Chief Justice John Roberts wrote for the court. “Winning, and doing so as inexpensively and decisively as possible, are not a candidate’s only interests in an election.”

The ruling reverses lower federal courts that had dismissed Bost’s lawsuit for lack of standing, finding his alleged injuries too speculative. The case now returns to the U.S. Court of Appeals for the 7th Circuit to decide whether Illinois’ law conflicts with federal statutes that set a single Election Day in November for congressional and presidential contests.

Illinois’ rule and the broader landscape

Under Illinois law, election officials must count vote-by-mail ballots that are postmarked or otherwise certified on or before Election Day and received within 14 calendar days afterward, through the period when provisional ballots are processed. Ballots lacking a clear postmark can be counted if other evidence, such as the voter’s certification or a postal barcode, shows they were completed on time.

The system has been in place since 2015 and is part of a broader move by many states to accommodate mail voting amid postal delays and rising use of absentee ballots. Roughly 16 or 17 states, along with the District of Columbia and several U.S. territories, allow ballots mailed by Election Day to arrive and be counted after the polls close.

Bost and two Republican activists, represented by the conservative group Judicial Watch, sued Illinois officials in 2022. They argue that counting ballots that arrive up to 14 days after the statutory Election Day effectively extends the federal election beyond the date Congress set in 2 U.S.C. § 7 and 3 U.S.C. § 1.

In court papers, the plaintiffs claimed the rule “dilutes” votes cast and received by Election Day, forces candidates to prolong and finance their campaigns while ballots trickle in and are counted, and risks narrowing their margins of victory in ways that damage their political standing.

Lower courts said the harm was too speculative

A federal district judge in Chicago dismissed the case in 2023, and a divided 7th Circuit panel affirmed last year. The appeals court said Bost’s fears were too remote, noting he won his last race with roughly three-quarters of the vote, and found that any added monitoring costs were expenditures he chose to make.

The Supreme Court took the case last year to resolve the standing issue and heard arguments in October. On Tuesday, the justices split sharply over how far to go.

Roberts: Candidates have a concrete stake in vote-counting rules

Roberts, writing for five conservatives, framed the standing question in plain terms. Standing doctrine, he said, asks: “What’s it to you?” Bost, he wrote, “has an obvious answer: He is a candidate for office.”

The chief justice said candidates have a “concrete and particularized interest in the rules that govern the counting of votes in their elections, regardless whether those rules harm their electoral prospects or increase the cost of their campaigns.” That interest, he added, extends to “the integrity of the election—and the democratic process by which they earn or lose the support of the people they seek to represent.”

Roberts rejected the lower courts’ insistence that Bost show a substantial risk that the Illinois rule would cause him to lose an election or significantly change the outcome.

“Requiring candidates to prove that particular election rules are likely to change electoral outcomes would force judges to make political prognostications about which neither judges nor anyone else can have any confidence,” he wrote. He added that tying standing to such predictions would push many challenges into “the tumultuous period immediately before or after an election,” when last-minute court orders can be most disruptive.

Barrett and Kagan: Standing, but on narrower grounds

Justices Amy Coney Barrett and Elena Kagan agreed Bost has standing but declined to join Roberts’ broader reasoning. In a separate opinion concurring only in the judgment, Barrett said the court did not need to create what she called a new, expansive rule for “candidate standing.”

Instead, she pointed to what she described as a traditional “pocketbook injury”: Bost’s allegation that Illinois’ 14-day window required him to keep paying campaign staff, lawyers and poll watchers while ballots were still arriving and being counted.

“That concrete financial harm is enough to confer standing,” Barrett wrote, warning that the majority’s more sweeping language was “unmoored from our precedent.”

Jackson and Sotomayor dissent

Justice Ketanji Brown Jackson, joined by Justice Sonia Sotomayor, dissented. Jackson called the case “an easy one” under longstanding rules requiring a plaintiff to show a concrete, particularized injury that is actual or imminent.

“In departing from that well-trodden path, the Court today pronounces that those rules no longer apply to candidates,” she wrote. “It creates a bespoke standing rule for this favored class of plaintiffs.”

Jackson argued that Bost’s interest in a fair electoral process is “a generalized grievance shared by all voters and citizens,” not a basis for federal jurisdiction. She also rejected the idea that campaign expenses spent monitoring ballot counting could create standing, saying plaintiffs “cannot manufacture standing by choosing to make expenditures based on hypothetical future harm that is not certainly impending.”

The dissent warned that the decision will “thrust the Judiciary into the political arena,” encouraging losing and winning candidates alike to bring speculative challenges to election rules across the country.

What comes next—and why it matters beyond Illinois

The practical stakes extend beyond the Illinois dispute. A separate case already before the court, Watson v. Republican National Committee, directly asks whether federal law bars states from counting mail ballots that are properly cast by Election Day but received afterward. That case involves a Mississippi statute that allows such ballots to arrive up to five business days late. A federal appeals court struck that law down, and a Supreme Court ruling is expected by June.

If the justices in Watson ultimately hold that federal law requires all mail ballots to be received by Election Day, states like Illinois, California and New York may have to rewrite their rules—and could be forced to discard thousands of ballots that are mailed on time but arrive days later.

The Bost ruling ensures that federal candidates will have a clearer path into court to press those kinds of challenges. Conservative groups hailed Tuesday’s decision as a victory for “election integrity” and a check on what they call overly permissive mail-ballot regimes. Voting-rights advocates and many election officials, by contrast, say extended receipt windows are vital for rural voters, people with disabilities, and communities served by slower or less reliable mail.

Roberts said allowing candidates to sue earlier in the process would bring “greater order and predictability” to election disputes. Jackson countered that opening the courthouse doors wider for candidates risks making federal courts another venue for campaign battles.

The merits of Illinois’ 14-day rule now return to the lower courts, but the terms of the broader fight have shifted. With the 2026 midterm elections on the horizon and another major mail-ballot case on the court’s docket, how—and how long—states can count votes cast by mail will again be decided not just in state capitols and election offices, but in federal courtrooms.