(credit: US Patent and Trademark Office)

One of the oldest and most profitable patent trolls, Uniloc, has been shot down. Its US Patent No. 5,490,216, which claims to own the concept of "product activation" in software, had all claims ruled invalid by the Patent Trademark and Appeals Board (PTAB).

The process through which PTAB eliminated the patent is called an "inter partes reexam," or IPR....