Citation Edit

In re Christensen, 478 F.2d 1392, 178 U.S.P.Q. (BNA) 35 (C.C.P.A. 1973) (full-text).

Factual Background Edit

The invention related to a method of determining the porosity of subsurface geological formations and centered on a mathematical technique for processing the results of physical measurements. Exercise of the mathematical technique constituted the last step in process claims otherwise limited to physical measuring operations. No machine implementation of the mathematical formula was disclosed.[1]

C.C.P.A. Proceedings Edit

While the C.C.P.A. was clearly of the opinion that the issue decided by the U.S. Supreme Court in Benson was narrowly drawn, it determined that in the Christensen claim reciting a new invention the “point of novelty” was a mathematical equation. Such an equation, the C.C.P.A. held, is not patentable. The steps involving establishing values for the variable steps which were not novel were not sufficient to render the invention patentable.

In a method claim in which the point of novelty is a mathematical equation to be solved as the final step of the method, a statutory method? We follow the Supreme Court in concluding that the answer is in the negative.[2]

Discussion Edit

But that was an unnecessarily broad reading of the Benson opinion, which had stressed the fact that the applicant's claims were "so abstract and sweeping as to cover both known and unknown uses of the BCD to pure binary conversion.”[3] The Christensen claims, on the other hand, were limited to the use of the formula in a porosity determining process and thus could not "preempt" unknown uses of the formula.[4] This was to be the broadest reading of Benson by the C.C.P.A.

Judge Rich, who had authored the first Benson opinion,[5] upholding Claim 13 on the very basis on which it was rejected by the Supreme Court, "reluctantly" concurred in the Christensen outcome: "I have no more doubt it is a 'process' within the meaning of §101 than I had about Benson's process; but on that point I seem to have been reversed."[6] Although he disagreed with its relevance to Section 101, he clearly recognized that the Supreme Court's decision turned on its perception of the "scope" and "breadth" of the Benson process claims.[7]


  1. Id. at 1392-93, 178 U.S.P.Q. (BNA) at 36-37.
  2. Id. at 1394, 178 U.S.P.Q. (BNA) at 37.
  3. 409 U.S. at 69, 175 U.S.P.Q. (BNA) at 675.
  4. 478 F.2d at 1392-93, 178 U.S.P.Q. (BNA) at 37-38.
  5. In re Benson, 441 F.2d 682, 169 U.S.P.Q. (BNA) 548 (C.C.P.A. 1971)(full-text), rev’d sub nom. Gottschalk v, Benson, 409 U.S. 63, 175 U.S.P.Q. (BNA) 673 (1972)(full-text).
  6. 478 F.2d at 1396, 178 U.S.P.Q. (BNA) at 39 (Rich, J., concurring).
  7. Id. at 1395-96, 178 U.S.P.Q. (BNA) at 38-39 (Rich, J., concurring).

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