The primary driver behind the 87.5% market-implied probability that the Supreme Court will not accept an AI copyright case before 2027 is the timeline of the sole federal appellate ruling to date. On September 29, 2026, the Third Circuit affirmed in *Thomson Reuters v. ROSS Intelligence* that using copyrighted Westlaw headnotes to train a competing legal-research AI tool did not qualify as fair use, distinguishing it from generative large language model cases. ROSS indicated plans to seek en banc review, which under Supreme Court rules would likely push any certiorari petition into early 2027. Broader multidistrict litigation involving OpenAI, Microsoft, Meta, and others remains in district-court discovery or early appeals with no circuit split or final judgments positioned for expedited Supreme Court review. Traders view the compressed window through 2026 as insufficient for the Court to grant certiorari on this novel intersection of copyright, AI training data, and fair use.