How does the Tarczy-Hornoch case relate to the “Mere Function of Machine” rule?

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.

The Tarczy-Hornoch case is a significant legal precedent that established the “Mere Function of Machine” rule in patent law. According to MPEP 2173.05(v):

“In re Tarczy-Hornoch, 397 F.2d 856, 158 USPQ 141 (CCPA 1968). The court in Tarczy-Hornoch held that a process claim, otherwise patentable, should not be rejected merely because the application of which it is a part discloses an apparatus which will inherently carry out the recited steps.”

This case established that process claims should be evaluated on their own merits, regardless of whether a disclosed apparatus would inherently perform the claimed steps. This ruling protects inventors from having their process claims unfairly rejected based solely on the functionality of a related machine or apparatus.