[Guvante]

Showing a patent clerk prior art is much easier than showing prior art in a courtroom.

For instance at the minimum you need to bring in an expert witness to explain the prior art. Then you have to contend with the fact that they will bring in their own expert witness to explain how your example is bogus and you both get to cross-examine. etc. etc.

[lisper]

Anyone can file a request for re-examination with the PTO.

http://www.uspto.gov/patents/stats/Reexamination_Information...