The Supreme Court and the Law of Nature Exclusion

In its March 20, 2012 opinion in Mayo Collaborative Services v. Prometheus Labs, Inc., the Supreme Court unanimously invalidated Prometheus’ patent claims based on the “law of nature exclusion,” explaining that routine, conventional activity cannot make natural correlations patent-eligible. 566 U.S. __. (2012).

Background on Section 101

Patent-eligibility is a threshold inquiry separate from novelty or innovation. Defined by Section 101 of the patent code, patent-eligible subject matter encompasses new processes, machines, manufactures, and compositions of matter. Specifically excluded from patent-eligibility, however, are laws of nature, physical phenomena, and abstract ideas.

In practice, challenging a patent based on (lack of) patent-eligibility may be easier than establishing patent invalidity based on other grounds. Lack of novelty, for example, may require extensive and costly searches, as well as expert reports/testimony, regarding obscure nuances of complex technologies. Because an inquiry into patent-eligibility does not require such evidence, patent infringement cases may be disposed of at an early stage of litigation by reference to patent-eligibility.

Conversely, patentees may be more likely to appeal adverse decisions related to patent-eligibility, because of the implications of such decisions may have on the ability to obtain patents on whole categories of subject matter. As a result, the issue of patent-eligibility has been revisited numerous times over the past several years. See Bilski v. Kappos, 130 S. Ct. 3218 (2010); Ass’n for Molecular Pathology v. U.S. Patent & Trademark Office, 653 F.3d 1329 (Fed. Cir. 2011); Classen Immunotherapies, Inc. v. Biogen Idec, 659 F.3d 1057 (Fed. Cir. 2011); Ultramercial, LLC v. Hulu, LLC, 657 F.3d 1323 (Fed. Cir. 2011).

Prometheus patent

In the present case, Prometheus markets a series of diagnostic tests covered by patent claims that essentially recite administering a thiopurine drug to an autoimmune patient and then determining a level of drug metabolites in the patient, which may be used by a doctor to judge whether the drug dosage is appropriate. Mayo claims that the claimed process attempts to monopolizes natural laws and natural phenomena, and is therefore not patent-eligible.

The Federal Circuit had upheld the Prometheus patent, finding that the drug administration and metabolite determination steps were transformative, which indicates that the process was not purely mental, abstract, nor a law of nature.

Law of Nature

On appeal before the Supreme Court, the issue was how to distinguish unpatentable laws of nature from patent-eligible applications of such laws. Allowing patents on laws of nature, natural phenomena, or abstract ideas would result in the monopolization of the basic tools of scientific and technological work, whereas “too broad an interpretation of this exclusionary principle could eviscerate patent law . . . [f]or all inventions at some level embody, use, reflect, rest upon, or apply laws of nature, natural phenomena, or abstract ideas.” Mayo, No. 10-1150, slip op. at 2.

In its opinion, the Supreme Court reversed the Federal Circuit, finding that the Prometheus process was not patent-eligible, because it failed to transform “unpatentable natural laws into patent-eligible applications of those laws.” Id. at 3. In particular, the relationship between drug metabolite levels and efficacy was determined to be a natural law, since the “relation itself exists in principle apart from any human action.” Id. at 8.

In analyzing the other steps (drug administration and metabolite determination), the Supreme Court notes that these “additional steps consist of well understood, routine, conventional activity already engaged in by the scientific community.” Id. at 11. For example, the purpose of the drug administration step was to trigger a manifestation of a natural law in a particular patient. Id. at 8. Further, the determining step was found to be “set forth in highly general language covering all processes that make use of the correlations.” Id. at 18. “[S]ince they are steps that must be taken in order to apply the laws in question, the effect is simply to tell doctors to apply the law somehow.” Id. at 13.


This decision may have implications for other patents in the medical and diagnostic fields, as well as those relying heavily on “natural correlations.” The Myriad case, for example, concerning the patent-eligibility of genes will likely be remanded to the Federal Circuit for reconsideration in light of this decision. While that case concerns a composition of matter (isolated DNA for breast cancer), patent challengers may now be able to argue that the correlation between DNA and breast cancer is a law of nature and that the isolated nature of the claimed DNA results from “well understood, routine, conventional activity already engaged in by the scientific community.”

The Supreme Court notes, however, that “[w]e need not, and do not, now decide whether were the steps at issue here less conventional, these features of the claims would prove sufficient to invalidate them.” Id. at 18. One implication is that patent-eligibility may be related to the nature of the additional subject matter surrounding the natural laws or phenomena relied upon. Patent applicants may therefore consider incorporating unconventional subject matter and subject matter that may not be required to apply natural law or phenomena, as well as describing the same with some specificity.


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