Addressing the best mode defense for possibly the last time in view of the America Invents Act of 2011 (AIA), the U.S. Court of Appeals for the Federal Circuit found that the best mode was not concealed if it was within the scope of knowledge of a person having ordinary skill in the art.  Joy Mining Machinery v. Cincinnati Mine Machinery, Case No. 12-1153 (Fed. Cir., Nov. 8, 2012) (Prost, J.) (nonprecedential).

Joy Mining Machinery (Joy MM) alleged that a mining machine used by Cincinnati Mine Machinery (CMM) infringed a patent owned by Joy MM, which claimed a chain and flight assembly that included a drive pin retaining means.  The patent only disclosed welding as a mechanism to implement the drive pin retaining means.  As a result, CMM asserted in its defense that Joy MM concealed press-fitting as the best mode for implementing the drive pin retaining means.  Press-fitting, however, was known to those of skill in the art to be a substitute for welding at the time of the invention, and neither party disagreed on this point. 

The Federal Circuit stated that to establish that the claims failed the best mode requirement, CMM must prove by clear and convincing evidence that the inventor of the patent concealed a best mode of practicing his claimed invention from the public.  The Federal Circuit noted that concealing a best mode of the invention turns on whether the inventor’s disclosure is adequate to enable one of ordinary skill in the art to practice the best mode of the invention.  Since there was no genuine dispute that one of ordinary skill in the art had the requisite knowledge necessary to use press-fitting to implement the drive pin retaining means, the Federal Circuit found that CMM could not prove that omission of press-fitting from the written description of the patent constituted concealment of the best mode.  Accordingly, the Federal Circuit reversed district court’s ruling that granted summary judgment to CMM for failure to satisfy the best mode requirement. 

Practice Note:  Since the new AIA prevents a post grant action that would challenge a patent as invalid or unenforceable based upon failure to disclose the best mode, this decision would have little or no impact on future patent cases.