The U.S. Supreme Court issued its ruling regarding the patent eligibility of medical diagnostic methods in the case of Mayo Collaborative Services v. Prometheus Laboratories (--- S.Ct. ----, 2012 WL 912952). The court reiterated its long-standing view that laws of nature are not patentable. However, the Court stated that application of a law of nature may be patentable if the relevant patent claims recite additional features that “provide practical assurance that the processes are genuine applications of those laws rather that drafting efforts designed to monopolize the correlations.” In the Prometheus case, however, the Supreme Court held that Prometheus did not claim the requisite transformation of the recited natural laws into “patent-eligible applications of those laws”.

Prometheus obtained two patents on methods for calibrating the dose of certain drugs for treating gastrointestinal disorders. The patented methods involve administering the drug and then measuring levels of a metabolite in order to optimize therapeutic efficacy. The Mayo Clinic challenged the patents, asserting that the claimed methods were not patentable subject matter because the claims patented a law of nature. The lower court agreed with the Mayo Clinic and invalidated the patents. On appeal, the Federal Circuit determined that the Prometheus claims were indeed patentable subject matter without addressing whether the disputed claims patented a law of nature.

The Court stated that the patent statutes should not be “interpreted in ways that make patent eligibility depend simply on the draftsman’s art” and thus claim “processes that too broadly preempt the use of a natural law”. Instead, claims that focus on natural laws must “contain other elements or a combination of elements . . . sufficient to ensure that the patent in practice amounts to significantly more than a patent upon the natural law itself.” What this means is that claims must clearly recite an “inventive” application or transformation of a natural law in order to be eligible for patent protection. It is unclear as to exactly what might be required in order to meet that burden. What is clear, however, is that patentees must be cognizant of the obligation to recite a clear application or transformation in any claim that refers to a “natural law”.