Supreme Court Considers Illinois’ Mail-In Voting Laws

The U.S. Supreme Court this week deliberated a pivotal question: can a political candidate challenge Illinois’ law permitting mail-in ballots submitted up to 14 days after Election Day to be counted — so long as they were postmarked by Election Day? In a case brought in 2022 by U.S. Rep. Mike Bost of Murphysboro and two Illinois Trump primary delegates, the plaintiffs contend that the state’s counting window forces campaigns to expend extra resources and could dilute their vote totals.

Lower federal courts have already dismissed the challenge, holding that Bost lacks the legal standing to bring suit. The Supreme Court’s task, however, is narrower. It must decide whether a candidate—even one who wins comfortably—has the right to sue under such circumstances. The justices explicitly declined at this stage to rule on the constitutionality of the Illinois mail-in voting provision itself.

During oral argument, justices pressed lawyers on where the line should be drawn for who may litigate election rules. Bost’s counsel, Paul Clement, asserted that the burden of paying campaign staff to monitor ballot counting past Election Day constitutes a concrete harm. He also warned that counting late ballots can undercut a candidate’s vote share, even in races with large margins. Clement further argued that a candidate’s margin of victory should not preclude standing — that even those with slim prospects must be able to challenge election rules.

Justice Sonia Sotomayor pushed back, emphasizing that federal courts are generally reserved for plaintiffs who can show a “concrete” injury. Meanwhile, Justice Neil Gorsuch countered that using viability or vote share as a gatekeeping measure undermines the principle that even fringe candidates deserve equal standing under the law. Bost’s electoral position — he has held Illinois’s 12th District seat since 2015 and won reelection in 2024 by an overwhelming margin — factored into the discussion, but the Court wrestled with whether that history should bear on his ability to sue.

In defense, Illinois Solicitor General Jane Notz argued that neither the prospect of receiving more votes nor a campaign’s incidental expenses give rise to standing. She maintained that the mail-in rule regulates voters, not candidates, and cautioned that permitting challenges from any disappointed contender would flood courts with litigants disputing harmless election rules. When Justices questioned her reliance on Bost’s experience and knowledge of electoral trends, Notz acknowledged that treating experienced and inexperienced candidates differently would be problematic. Justice Alito asked bluntly whether a candidate’s personal background should determine access to courts, while Justice Kagan noted that requiring viability evidence or polling would unfairly disadvantage newcomers.

Justice Ketanji Brown Jackson further warned that adopting a “margin” test for standing could invite countless post-election disputes from losing candidates demanding tweaks to their margins. Notz argued that other legal avenues — such as ballot access rules or campaign finance restrictions — might offer clearer standards for who may challenge election law. She also cautioned that giving all candidates standing to sue could divert election administrators’ attention toward defending policy disputes rather than running elections.

The Supreme Court is expected to issue its ruling by next June. A decision in Bost’s favor would allow his suit to proceed in lower courts, possibly bringing the constitutionality—or at least the legality—of Illinois’ delayed ballot counting window into full judicial scrutiny.