Takeaway: You must mark your products to recover past damages from an infringer.
Federal patent law allows for the recovery of up to six years of past damages in a patent infringement action. To be eligible for past damages, a patentee, or a patentee’s licensee, must mark its products with the words “patented” or “pat.”, followed by either the patent number or an internet address where the applicable patent numbers may be found. These long standing principles were recently reaffirmed by the Federal Circuit Court of Appeals in Arctic Cat Inc. v. Bombardier Recreational Products Inc., Case No. 17-1475 (Feb. 2020) (denying patentee recovery for past infringing sales where patentee’s licensee failed to mark the patented product).
Patentees must ensure proper marking. Proper marking provides constructive notice to consumers and competitors of the existence of a patent, and is often an important issue in patent infringement actions. A failure to mark a patented product limits a patentee to damages only for sales that occur after an infringer has actual notice of the patent. Actual notice typically occurs upon receipt by an infringer of a cease and desist letter or the date a suit is filed. Relying upon actual notice, while sufficient for injunctive actions, typically precludes a patentee from any meaningful recovery of money damages.
At Cislo & Thomas, in a recent matter we were able to prevent a threatened patent infringement action where investigation revealed that the patentee’s subsidiary failed to mark the patented products and therefore precluded the patentee from recovering money damages for the alleged infringer’s past sales.