View source for Case 10: Diamond v. Diehr (1981)

Diamond and his crew filed a petition for a patent which would mold raw rubber into precise shapes. This process had been difficult in the past because of the uncertainty surrounding the proper curing time. This uncertainty stemmed from the fact that determining the temperature inside the molding press was problematic. The cure time is related to the temperature by a known mathematical formula; the respondents developed a system by which the temperature inside the press was continuously fed into a computer program that would automatically open the press at the right time. They were at first denied a patent, but the court later held that they were in fact entitled to a patent.

This case cited the Cochrane case, which defined a process as "an act, or a series of acts, performed upon the subject-matter to be transformed and reduced to a different state or thing. If new and useful, it is just as patentable as is a piece of machinery .... The machinery pointed out as suitable to perform the process may or may not be new or patentable." In this case, the respondents claimed that the constant monitoring of the temperature, the continuous recalculation of the cure time, and the signaling of the opening device were all new. The patent examiner deemed the application unpatentable due to its use of a mathematical formula. The process includes installing rubber in the press and closing the press, both of which were necessary aspects of the art. This leaves only the computer formula and the electronic signal. The examiner believed that this part of the process was nonstatutory subject matter and could not be patented.

This assessment is incorrect. Just because a computer is involved does not mean the subject isn't patentable. Furthermore, the respondents were not looking to patent a mathematical formula; rather, they sought to use a mathematical formula in conjunction with other steps to solve a problem which had existed in the process of making rubber; they were using the formula as a tool to improve an existing method. In Benson, the mathematical formula was solely for use in a digital computer, and the Court treated it as a fundamental law of nature. Likewise in Parker, the claim was not for a greater process of determining values or gathering data, but solely for a mathematical formula for an "alarm limit." Thus, this claim was not patentable. In the current case, the patent is not only for the mathematical formula, but for all the other steps taken in the process.

The thrust of this ruling is that the components of a patent must be considered as a whole. One cannot separate into old and new parts and ignore the old stuff. Indeed, this method would preclude large numbers of patentable processes where the individual parts are well known and not new. However, questions of novelty are a separate matter from questions of patentable subject matter. Under 101, the claims above are patentable. In other cases, a mathematical formula may not be patented, whether it is a general formula or specified to a particular technological function. In addition, the presence of meaningless steps after the use of the formula does not make it patentable.