What Happened
Patent law has a simple rule: if you sell patented products, mark them with the patent number. If you don't, you can't recover damages for infringement that occurred before you gave actual notice to the infringer. That could mean losing years of damages.
Why It Matters
Here's the math: You sue for patent infringement. The infringement started five years ago. But you never marked your products, and you never sent a cease-and-desist letter until filing suit. Your damages are limited to the period from filing forward—maybe a few months. The prior five years? Gone.
Marking doesn't have to be complicated. Put "Pat." or "Patent" followed by the patent number on the product or packaging. Or use "virtual marking"—put a website URL on the product and list your patents on that website. Virtual marking is easier to update when patents expire or new ones issue.
The rule applies to licensees too. If you license your patents, make sure your licensees mark products. Their marking benefits you and provides constructive notice to the industry.
What You Should Know
If you sell patented products, implement a marking program. Mark everything. Use virtual marking for flexibility. Update markings when patents expire. Audit your program regularly.
If you license patents, include marking requirements in your agreements. Monitor compliance. Require reporting.
If you're enforcing patents, document when you started marking and when you gave actual notice. Your damages period depends on it.
Marking is simple but often overlooked. Don't let this basic step cost you significant damages.