1. ... The fact remains that one of the best bets for having a patent invalidated is published
prior art that is not already cited in the patent.

2. The Richter Scale - Intellectual Property, Part 2

Once an application has been filed, a patent examiner reviews it to see if it might conflict with some "prior art". Prior art refers to other patents and published materials on the topic a patent is being sought for, as well as other products that may clearly have implemented the technology prior to the filing date of the application. There is usually at least one request by the PTO to the filer to make a change in the application because of one or several claims being too broad.

If you are threatened by patent infringement, you don't have a whole lot of choices (as the final scenario in my first IP column a couple of weeks ago indicated). Other than being able to convince the PTO to reexamine a patent (which requires lots of published prior art), the only other way to fight a patent, once it's been granted, is by spending lots of money in the courts, in addition to producing prior art (published or internal) which may help invalidate the patent.



3. ...If it is published prior art,
you can't patent it.

csf.colorado.edu/archive/2001/energy/msg00825.html