An accused infringer can plead many defenses such as patent invalidation, inequitable conduct, patent misuse, anti-trust and equitable estoppel. In patent infringement cases, parties often raise the defense of patent invalidity due to inequitable conduct by the patentee. Inequitable conduct is defined as a failure to disclose material information, or submission of false material information, with an intent to deceive, and those two elements, materiality and intent, must be proven by clear and convincing evidence.
After the accused infringer defendant has established threshold findings of materiality and intent, the court applies a balancing test in which the court weighs the materiality of the prior art and evidence of the applicant's intent to deceive the PTO to determine whether there was inequitable conduct.
The infringer, when he knew of the opponent patent protection, investigated the scope of the patent and formed a good faith belief that it was invalid or that it was not infringed. Defendant immediate action on infringement suit is to challenge the validity of patent by identifying close prior art against claims.
We focus on identifying relevant excerpts from the prior art which anticipates the asserted patent or renders it obviousness.