Can a patent with prolix claims be invalidated after issuance?

Yes, a patent with prolix claims can potentially be invalidated after issuance, particularly on grounds of indefiniteness under 35 U.S.C. 112(b). While the MPEP 2173.05(m) guidance on prolix claims is primarily for examiners during prosecution, the underlying principle of claim clarity remains relevant post-issuance.

In post-grant proceedings or litigation, if a court determines that the prolix nature of the claims renders them indefinite to the point where “the metes and bounds of the claimed subject matter cannot be determined,” the patent could be found invalid. This aligns with the Supreme Court’s decision in Nautilus, Inc. v. Biosig Instruments, Inc., which held that a patent is invalid for indefiniteness if its claims, read in light of the specification and prosecution history, fail to inform those skilled in the art about the scope of the invention with reasonable certainty.

It’s important to note that the threshold for invalidating an issued patent is generally higher than for rejecting a claim during examination. However, excessively prolix claims that obscure the invention’s scope can still pose a significant risk to the patent’s validity.

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Topics: MPEP 2100 - Patentability, MPEP 2173.05(M) - Prolix, Patent Law, Patent Procedure
Tags: indefiniteness, Patent Invalidation, Patent Litigation, post-grant proceedings, Prolix Claims