The following is excerpted from a July 6, 2011 post by Jason Witten at his Intellectual Property Solicitor blog:
The USPTO recently released statistics on patent reexaminations going back to 1982 [through March 31, 2011].
Interestingly, in the last 30 years there have only been 11,415 reexamination petitions. Compared to the number of patents issued every year (this year more than 200,000), that isn’t a very large number. Of these, about 2/3 have been filed by third parties against their opponents, and about 1/3 of the patents reexamined were known to be in litigation.
Notably, though, while there were only 187 petitions in 1982, there were 780 last year, and that represented about a 20% increase over just the year before. So they seem to be on the rise. I think the following statistics explain why:
– 66% of the patents have had their claims changed; and
– 11% have had their claims completely cancelled, thus killing the patent.
You can read the full post and view the stats via the link available here.