Inequitable conduct

In United States patent law, a claim of inequitable conduct is a defense to allegations of patent infringement. Even in an instance when a valid patent suffers infringement, a court ruling on an allegation of infringement may exercise its power of equitable discretion not to enforce the patent if the patentee (the patent owner) has engaged in inequitable conduct.

Inequitable conduct occurs when a patent applicant breaches the applicant's duty of candor and good faith to the US Patent and Trademark Office while applying for a patent. This breach can include:

See Therasense, Inc. v. Becton. A reference is material if "there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent."

The party asking the court to decline to enforce the patent, usually the alleged infringer, bears the burden of proving inequitable conduct to the court. The moving party must show by clear and convincing evidence that the patentee intentionally withheld or misrepresented information, and that the information was material. Proven inequitable conduct in any claim can expose the entire patent to unenforceability.

The U.S. Patent and Trademark Office's Rule 56 explains that patents are "[A]ffected with a public interest. The public interest is best served, and the most effective patent examination occurs when, at the time an application is being examined, the Office is aware of and evaluates the teachings of all information material to patentability." Accordingly, each individual person "associated with the filing and prosecution of a patent application has a duty of candor and good faith in dealing with the Office, which includes a duty to disclose to the Office all information known to that individual to be material to patentability."

The unclean hands cases of Keystone Driller v. General Excavator, Hazel-Atlas v. Hartford, and Precision v. Automotive formed the basis for the doctrine of inequitable conduct that developed and evolved over time.

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Wikipedia