The Copyright Act of 1976 stipulates that a plaintiff must file an infringement suit “within three years after the claim accrued.” For many years, courts have disagreed over when that three-year clock actually starts ticking.
Some courts, including some Circuit Courts of Appeal, have held it starts running when the alleged infringement occurred and that suits filed three or more years after that time are not valid. Other courts have held that the statute of limitations only start running when the plaintiff discovers, or reasonably could have discovered, the infringement, even if it occurred more than three years prior — an interpretation known as the “discovery rule.”