Labeling a patented product with a patent number is called “patent marking.” There is no requirement to mark your patented products, however, failure to mark can limit the amount of money (damages) you would be awarded in a lawsuit for patent infringement. You can seek damages for up to six years of infringement prior to filing a lawsuit, but only if the accused infringer knew about your patent. This knowledge requirement can be met by actual notice (e.g., notifying the infringer), or constructive notice by marking your products. See 35 U.S.C. 287(a). So, marking your products can significantly increase the amount of damages you may be entitled to by allowing you to seek pre-suit damages from all infringers, whether or not they actually knew about your patents.
Patent marking can also provide other benefits – it can help prevent copycats and unnecessary lawsuits by notifying competitors of your patent coverage and it can be used as a marketing tool by sending a signal to customers that your products are innovative.
How to Mark
You can mark your products by labeling the product itself with the word “Patent” or “Pat.” followed by the patent number(s) or a URL to a free-to-access webpage where the patent numbers are listed. The benefit of using a webpage is ease of revision -- as new patents are granted and older patents expire, only the webpage needs to be updated rather than the actual products and/or packaging. You should mark substantially all of your products, not just some of them, and the marking should be substantially continuous over the life of the product and patent. Also, if you license any of your patents, you should ensure your licensees are correctly marking the licensed products.
Federal Patent Law provides a cause of action against bad actors that intentionally falsely mark unpatented products as patented in order to gain an unfair advantage in the marketplace. See 35 U.S.C. 292. False marking is generally not something that companies that are making their best effort to correctly mark products should be concerned about. For example, a company will not be liable for false marking for continuing to mark a product with a patent number of an expired patent. A company should, however, periodically review its patent portfolio and current products and update its patent marking as needed.