In re Foster, 438 F.2d 1011, 169 U.S.P.Q. (BNA) 99 (C.C.P.A. 1971) (full-text).
Factual Background Edit
The invention presented was a mathematical method for correcting distortion in seismograms, and a digital computer was disclosed as a possible mode of practice. The Patent Office raised Section 101 objections because the "signals" alone could be read on visible patterns, which might be subjected to manual manipulation (human implementation), rather than limited to machine implementation.
C.C.P.A. Court Proceedings Edit
The court felt had been answered in In re Musgrave and In re Mahony. Other method claims were held patentable over the contention that their "means-plus-function" language encompassed a human being as the means or a part of the means.
By contrast, the claims"electrical signals" were found to read only on machine implementations of the process, since the signals in those claims were limited to a form recognized in the art as limited to machine implementation.