[mullingitover]

I'd really like to see a cite for this claim. I looked and could find zero reference to a patent holder's responsibility to enforce in order to maintain a patent's validity. AFAIK a patent holder is free to enforce their patent as they see fit, just as a copyright holder can. Otherwise there could be no such thing as a purely defensive patent, no?

Edit: Here we go[1]. So a patent holder can lose their ability to collect damages if they notify an infringer of their infringement but then fail to take action against that particular infringer within a certain period. There's no damage to the patent merely because of selective (or absence of) enforcement.

[1] http://www.lawabel.com/patent-damages-laches-and-equitable-e...

[pyre]

I didn't meant that it would make legal action impossible, but that it might affect the outcome. E.g.:

- You collect a super small licensing fee from one entity and are attempting to extract a super large settlement from another.

- You (provably in court) know that Apple is infringing, but only decide to pursue action against Microsoft. This could affect, for example, you damage claims (i.e. your claims that MS owes you 'back dated' licensing fees).