How to invalidate a patent?
When a patent is issued, there is a presumption that the patent satisfies the requirements that the invention is new and unobvious. However, a granted patent is not an absolute decree that the patent is valid. In fact, because of the sheer bulk of patent applications that the USPTO receives combined with the difficulty in locating prior art, the chance is high that many patents should not have been issued. If a patent infringement lawsuit is initiated against an infringer, a typical defense is that the patent is invalid and if proven then the patent owner cannot recover for infringement on that patent.
