On March 20, 2012, the United States Supreme Court issued its ruling in Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. ___ (2012). At issue were two patents covering the use of thiopurine drugs to treat autoimmune conditions such as Crohn’s disease. The Supreme Court concluded that the claims were impermissible attempts to patent a natural law, and held the patents invalid.  

Section 101 of the Patent Act allows an inventor to obtain a patent on “any new and useful process, machine, manufacture, or composition of matter.” The Supreme Court has held that implicit in Section 101 is an exception prohibiting patents on “laws of nature, natural phenomena, and abstract ideas.” The Court frequently gives examples that a newly discovered mineral or wild plant would not be patentable, nor would Einstein’s theory of relativity or Newton’s law of gravity.

Thiopurine drugs are man-made, and when taken by a patient, the body converts them into metabolites. However, each patient metabolizes the drugs differently, so the same dose can result in different levels of metabolites in different individuals. Researchers determined that low levels of the metabolite make the treatment less effective, while high levels can be harmful or fatal. Prometheus obtained patents on this research that claimed three steps: (1) an “administering” step in which the drug is given to a patient, (2) a “determining” step in which the metabolite levels are determined, and (3) a “wherein” step that counsels doctors to increase or decrease subsequent doses based upon approximate metabolite levels. Utilizing the patents, Prometheus produced and marketed a diagnostic test for the metabolites. Mayo initially purchased and used Prometheus’s test; however, in 2004, Mayo decided to sell its own test using slightly different correlation levels.  

When sued for infringement, Mayo argued that the processes claimed by Prometheus’s patents were claims to natural phenomenon or natural laws, and therefore unpatentable. The District Court held that Mayo’s test infringed, but granted summary judgment for Mayo on the ground that the patents claimed natural laws or natural phenomenon. The Federal Circuit reversed, ruling that Prometheus’s claims were patent-eligible because they did more than merely state a natural correlation by specifying steps that resulted in a transformation of the drug into measurable metabolite levels, thus satisfying the Federal Circuit’s “machine or transformation test.”  

The Supreme Court disagreed with the Federal Circuit, and remanded, instructing the Federal Circuit to reconsider its decision in light of the Supreme Court’s Bilski decision, which held that the “machine or transformation test” was not a bright line rule but an “important and useful clue” as to patent eligibility.

The Federal Circuit reconsidered, but came to the same conclusion that “the claims do not encompass laws of nature or preempt natural correlations.” Mayo appealed once again to the Supreme Court, which granted Mayo’s petition. In its opinion, the Supreme Court held that the correlation between specific drug metabolite levels and the efficacy of the treatment was an unpatentable law of nature. According to the Court, Prometheus’s patent claims do not add enough to the recitation of the law of nature to qualify as a patentable application of it. Moreover, the fact that the human body transforms the drug into metabolites is not sufficient to make an otherwise unpatentable law of nature patentable under Section 101. The Supreme Court explained that while the machine or transformation test can be an important and useful clue, it does not trump the law of nature exclusion on patentability.  

The Supreme Court looked to some of its prior decisions that evaluated the patentability of natural laws. In Diehr, the Supreme Court held that a method for molding rubber into products through the use of a mathematical equation was eligible for a patent. Although the mathematical formula was not patentable, the application of the formula to an automated process was patentable. In contrast, the Supreme Court held that the process in Flook was not patentable because it merely recited a mathematical formula for determining alarm limits in catalytic converters, without disclosing any inventive patentable process for its use.  

The Supreme Court analogized the claims in Prometheus’s patents to the unpatentable mathematical formula in Flook. “[T]he claim simply tells doctors to: (1) measure (somehow) the current level of the relevant metabolite, (2) use particular (unpatentable) laws of nature (which the claim sets forth) to calculate the current toxicity/inefficacy limits, and (3) reconsider the drug dosage in light of the law.” This process, according to the Court, adds nothing to the claimed laws of nature other than “routine, conventional activity, previously engaged in by those in the field.”  

Acting as amicus curiae, the United States Government argued that if the process claimed by Prometheus’s patent is routine or conventional, the proper basis for invalidating the patent would be lack of novelty under Section 102 or obviousness under Section 103. The Supreme Court nonetheless rejected this argument, and in doing so may have created some overlap between Section 101 and Sections 102 and 103.

It will be interesting to see how (or if) the Federal Circuit applies its “machine or transformation test” in light of Prometheus. The Federal Circuit and the Supreme Court clearly had a different view of the effect of Bilski on the test, and Prometheus appears to marginalize the test even further. Before Bilski, the Federal Circuit used the machine or transformation test as both a necessary and sufficient condition for patentability under Section 101. After Bilski, passing the test was no longer a necessary condition for patentability, but the question of whether it was still a sufficient condition for patentability remained. The Federal Circuit’s decision on remand suggested that it continued to view the test as outcome determinative for patentability, but not for unpatentability. In Prometheus, the Supreme Court disagreed and said that the test provides no certainty either way, but only “important and useful clues.” Today, it appears that failing the test may not guarantee unpatentability, nor will passing the test guarantee patentability.