The defense of misconduct infringement

In American patent infringement litigation, misconduct is one of the defenses of the accused infringer to the infringement charge. If the court finds that any claim has related misconduct, it may decide that the whole patent, even the whole patent family, is unenforceable. Even if the patent is valid and the infringement is established, the court will not support the patentee's claim.

The burden of proof to prove misconduct lies with the accused infringer. To prove the existence of improper behavior, the accused infringer must prove (1) that the patent applicant (or agent) has not disclosed important material information or submitted false material information to the Patent Office, and (2) these behaviors are aimed at deceiving and misleading the Patent Office. Because these are heavy burdens of proof, the respondent's lawyer should carefully check and read all relevant documents and statements of the patent applicant and his agent during the patent application process, that is, patent books, the evolution of claims, correspondence and statements with the patent office, and relevant published prior art. Should focus on finding inconsistent or misleading words and deeds of the applicant or agent.