In re Abele and Marshall, 1982
In the History of Software Patents, this is an often cited case. This invention related to image processing particularly as applied to computerized axial tomography or CAT scans. Specifically, the invention was directed to an improvement in computed tomography whereby the exposure to X-ray is reduced while the reliability of the produced image is improved.
The Examiner at the U.S. Patent and Trademark Office rejected the claims on appeal under the authority of Parker v. Flook. The examiner construed Flook as mandating the following test:
Taking each claim as a whole, it is assumed, for analysis purposes only, that any mathematical calculation in the claim is part of the prior art. If what is left is new and unobvious, then the claim, taken as a whole, protects more than a mathematical calculation and it is deemed statutory. But if the remainder of the claim is not novel nor unobvious, then the claim, taken as a whole, merely seeks to protect the mathematical calculation and, as such, does not comprise statutory subject matter.
Applying the above test, the examiner determined that, apart from the mathematical calculations, the remaining steps were well known or were “merely a necessary antecedent step to provide values for solving the mathematical equations,” and, thus, were directed to nonstatutory subject matter.
The Board of Patent Appeals and Interferences did not address the examiner’s contentions, relying instead of In re Freeman, as modified by In re Walter. The board affirmed the rejection as follows:
When the claims are analyzed in [the manner dictated by Walter], it is manifest that the mathematical algorithm is not implemented in a manner to define structural relationships between physical elements in the apparatus claims or to refine or limit claim steps in the process claims. The claims do no more than present and solve a mathematical algorithm and are manifestly nonstatutory.
The United States Court of Customs and Patent Appeals noted that in the Walter case, the claims were directed to a process6 for correlating and cross-correlating signals. All of the claims steps were algorithm steps for performing the correlation or cross-correlation. There were no limitations in the claims, other than a field of use set forth in the preamble of the claims which stated that the algorithm was for use in connection with seismic surveying. The court concluded that the claims were directed to claiming only the algorithm, were not applied in any manner to any process steps, and were, therefore, directed to nonstatutory subject matter.
The court stated that Walter should be read as requiring no more than that the algorithm be “applied in any manner to physical elements or process steps,” provided that its application is circumscribed by more than a field of use limitation or non-essential post-solution activity. Thus, if the claim would be “otherwise statutory,” albeit inoperative or less useful without the algorithm, the claim likewise presents statutory subject matter when the algorithm is included. This broad reading of Walter is in accord with the Supreme Court decisions.
The court went on to say that the goal is to answer the question “What did applicants invent?” If the claimed invention is a mathematical algorithm, it is improper subject matter for patent protection, whereas if the claimed invention is an application of the algorithm, §101 will not bar the grant of a patent.
In answering that question, each invention must be evaluated as claimed; yet semantogenic considerations preclude a determination based solely on words appearing in the claims. In the final analysis under §101, the claimed invention, as a whole, must be evaluated for what it is.
Applying this test, the court noted that each of the independent claims and, necessarily, each of the dependent claims, included the limitation “calculating * * * the difference” either as a step in a process or as a means in an apparatus. Accordingly, all of the claims may be directed to nonstatutory subject matter as each presents a mathematical formula or a sequence of mathematical operations.
The court then turned to the second part of the analysis to determine whether what is claimed is a statutory process or apparatus or a nonstatutory algorithm.
The court contrasted the two broadest process claims, claims 5 and 6:
5. A method of displaying data in a field comprising the steps of
calculating the difference between the local value of the data at a data point in the field and the average value of the data in a region of the field which surrounds said point for each point in said field, and
displaying the value of said difference as a signed gray scale at a point in a picture which corresponds to said data point.
6. The method of claim 5 wherein said data is X-ray attenuation data produced in a two dimensional field by a computed tomography scanner.
The court concluded that claim 5 is directed solely to the mathematical algorithm portion of appellants’ invention and is, thus, not statutory subject matter under § 101. The court reached the opposite conclusion with respect to claim 6.
The method of claim 6, unlike that of claim 5, requires “X-ray attenuation data.” The specification indicates that such attenuation data is available only when an X-ray beam is produced by a CAT scanner, passed through an object, and detected upon its exit. Only after these steps have been completed is the algorithm performed, and the resultant modified data displayed in the required format.
Absent the algorithm, the production, detection and display steps would still be present and would result in a conventional CAT-scan process. Accordingly, production and detection cannot be considered mere antecedent steps to obtain values for solving the algorithm.
Other claims were analyzed in a similar manner.