The statute of limitations, with respect to false marking claims, is five years – for you obsessive-compulsive personalities, it’s set forth at 28 USC §2462. Suit is barred in respect of any act occurring outside the statute period. The critical question – especially if you’re a “marking troll” – is "when does the statute of limitations begin to run?"
Does it begin, for example, when the particular production run began, or when the false marking first occurred? Well, ponder no more, a court has provided the answer. (Seirus Innovative Accessories, Inc. v. Cabela’s, Inc.)