But there's a six-year statute of limitations - a patent owner can sue [EDIT: for damages] for pre-expiration infringement up to six years after the infringemen

But there's a six-year statute of limitations - a patent owner can sue [EDIT: for damages] for pre-expiration infringement up to six years after the infringement. (There may be potential wrinkles in the analysis if the infringement was an on-going one.) EDIT: What the patent owner can't do after expiration is get an injunction against further infringement.