Simply, one can invalidate a patent if you can demonstrate that "prior art" existed. The only problem with that is that the burden of proof falls on you. Have your legal team examine the patent and the prior art and then with their approval you can "infringe". If the patent holder sues, you can reply with the prior art. Then it becomes a problem for the patent holder to prove the diferences from teh prior art. This happens all the time. Hans Mellberg __________________________________________________ Do You Yahoo!? Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu