To avoid damaging your patent rights, mark your products with patent numbers. The law (35 USC 287) covers devices but not methods, so marking software is a bit tricky.
You probably have noticed many products marked with the word “US patent,” followed by a list of patent numbers. These numbers are usually written in small type somewhere on the product or its packaging. If you (as a patent holder) are planning to start producing your own patented products, what happens if you don’t include this marking?
It is hard to tell what is and isn’t patented. So Congress passed Federal law 35 USC 287 to protect the public from accidental patent infringement. 35 USC 287 holds that absent such marking, your ability to recover past damages from an infringer can be minimal. For example, you can only claim losses back to the time (presumably after suitable claim chart analysis), that you first sent a notice letter to the infringer.
Not good. Someone may have been infringing for years before you first detected a problem. To more fully recover your losses, you need to mark your products.
The law covers patent licensees as well.
This law also covers your patent licensees. The problem is that patent licensees often forget to include these markings. So remember to include a marking requirement in your license negotiations. Otherwise, your licensee could end up accidentally damaging your rights. See, for example, Federal Circuit Decision 2019-1080, “Arctic Cat v. Bombardier Recreational Products.”
Online marking can be OK.
Although traditionally, you had to mark the product itself, a few years ago, it became OK just to use “virtual marking.” Here, just marking “patent or pat,” followed by a publically accessible web page address, is enough. Virtual marking has advantages, but make sure the web page is actually “up.”
To prevent inadvertent loss of rights, it may seem safer to always err on the side of marking, but don’t overdo it. There is a different law, 35 USC 292, designed to protect the public against false patent marking. So the general rule of thumb is to try to provide adequate patent notice, but avoid being deceptive.
35 USC 287 has some “bugs” and “features.”
Bugs: Untended consequence — the law favors patent trolls! A patent holder who doesn’t produce anything (and hence has nothing to mark) can still recover past damages from up to six years earlier.
Features: Because it is hard to affix a mark to a method, 35 USC 287 generally doesn’t apply to methods patents.
But what about software and software implemented inventions? Software patents often contain a mixture of methods claims and device claims. However, software typically runs on (or is stored in) some sort of physical object. So is software covered by 35 USC 287 or not? If so, what to mark, and how to mark it? What about websites and apps?
The courts have not been consistent here, and the law is still evolving. However, a fair number of court cases have required marking. You should assume that patent marking is likely needed, and then examine legal aspects as they apply to the specifics of your situation.