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Mayo v. Prometheus: Implications for the Patent Eligibility of Computer-implemented Technologies

June 15, 2012

How to distinguish patent eligible subject matter from laws of nature, natural phenomena, and abstract ideas that are not patent eligible, continues to be a hot topic in both Canada and the United States. In November of 2011, the Federal Court of Appeal in Canada decided, (see Canadian Patent Office Allows "1-Click" Patent for more detail) rejecting the approach taken by the Commissioner of Patents in finding that a patent application for purchasing items over the Internet using a single-action, was an unpatentable business method. More recently, in its unanimous decision in Mayo v. Prometheus (Prometheus) of March 20, 2012, the United States Supreme Court considered how to distinguish applications of laws of nature that are patent eligible, from those that are not. Although Prometheus concerned the validity of a claim in the medical field, the case has implications to claim validity in other fields (such as computer-implemented technologies), where courts also struggle with this distinction.

The Prometheus claims defined a relationship between the concentration of a metabolite in the blood and the likelihood that drug dosage would be ineffective or toxic. The Court called this relationship a law of nature, and noted that patent claims that cover the use of a natural law too broadly pre-empt the use of that natural law. Thus, to be patent eligible, a process claim that covers the use of a natural law must also recite other elements or a combination of elements, sufficient to ensure that the claimed invention amounts to significantly more than the natural law itself. In Prometheus, the claims recited steps or elements (administering the drug and determining the relevant level of the metabolite) in addition to the law of nature. However, these steps added nothing of significance to the natural laws themselves. Thus, the claims did not define a patent eligible process. (See Determining Patentable Subject Matter in the United States and Canada for more detail.)

When are additional steps significant enough to render an application of the law of nature, abstract principle or mathematical formula patent eligible? Prometheus provides two ways to assess significance. First, the claim must not pre-empt or monopolize the law of nature. That is, the additional elements added to the claim must narrow the scope of the claim sufficiently to avoid monpolizing the law of nature. Second, the additional elements must not be merely routine and conventional (i.e., well-understood in the relevant skilled community) such that when viewed as a whole, the additional elements add nothing significant beyond the sum of their parts taken separately. According to the Court, the additional elements failed to be significant in both respects.

Regarding the natural laws recited in the Prometheus claims, the Court noted that “[a]nyone who wants to make use of these laws must first administer a thiopurine drug and measure the resulting metabolite concentrations, and so the combination amounts to nothing significantly more than an instruction to doctors to apply the applicable laws when treating their patients.” The Court also held that “the claims inform a relevant audience about laws of nature; any additional steps claimed [apart from the natural laws themselves] consist of well-understood, routine, conventional activity already engaged in by the scientific community, and, those steps, when viewed as a whole, add nothing significant beyond the sum of their parts taken separately.”

Many inventions rely on computers that have been programed according to mathematical formulae to execute series of steps. If the inventiveness of these inventions lies entirely in the mathematical formulae, and not in the well-understood and routine steps of programming computers according to the mathematical formulae, then the validity of patent claims to these kinds of inventions may be suspect under the second test described above. On the other hand, say that the additional steps recited in the method, although perhaps conventional, also narrow the claim sufficiently so that others are free to use the mathematical formulae, even free to program computer processors according to the mathematical formulae, provided these others do not also implement the additional steps recited in the method.

In Prometheus, the Court quoted with approval its finding in Diamond v Diehr (Diehr), that "an application of the law of nature or mathematical formula to a known structure or process may well be deserving of patent protection." In that case, the process claimed defined a method for molding raw, uncured rubber into various cured molded products. The steps claimed included "installing rubber in a press, closing the mold, constantly determining the temperature of the mold, constantly recalculating the appropriate cure time through the use of the formula and a digital computer, and automatically opening the press at the proper time." The Court in Diehr found this method to be patent eligible. According to the Court in Prometheus, Diehr nowhere suggested that all these steps, or at least the combination of those steps, were in context obvious, already in use, or purely conventional. Also, the Court in Diehr found that the patent applicants “do not seek to patent a mathematical formula. Instead, they seek patent protection for a process of curing synthetic rubber. Their process admittedly employs a well-known mathematical equation, but they do not seek to pre-empt the use of that equation. Rather, they seek only to foreclose from others the use of that equation in conjunction with all of the other steps in their claimed process." Thus, the additional steps recited in the Diehr claims were “significant” in that they changed the character of what was claimed from mathematical formula to a process for curing rubber.

Applying Diehr, patent claims for computer-implemented inventions should be worded to claim an invention that is not a mere application of a mathematical formula or an abstract idea, but instead can be characterized as something significantly more. How to achieve this will vary from invention to invention. Prometheus, however, warns of the risk of patent claim invalidity, if a court concludes that the claim pre-empts the use of the mathematical formula, in that the additional elements recited by the claim must be implemented to apply the mathematical formula.

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Ian McMillan Ian McMillan
B.Sc. (Math & Eng.), LL.B., LL.M.
905.817.6103  email Ian McMillan