Can some claims in a patent remain valid if inequitable conduct is found?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

No, according to MPEP 2016, if inequitable conduct is found, it affects all claims in the patent. The MPEP cites the case J. P. Stevens & Co. v. Lex Tex Ltd., which states:

“Once a court concludes that inequitable conduct occurred, all the claims — not just the particular claims in which the inequitable conduct is directly connected — are unenforceable.”

This principle is often referred to as an “all or nothing proposition,” meaning that partial unenforceability is not an option when inequitable conduct is found.