Best Mode Defense’s Last Stand

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 Cir., Nov. 8, 2012) (Prost, J.) (nonprecedential).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