Prometheus Undone

March 23, 2012, 2:49 PM

What constitutes patentable subject matter has been a question of keen interest to the courts in recent years. The most recent chapter came on March 20, 2012 with the Supreme Courts unanimous decision in Mayo Collaborative Services v. Prometheus Laboratories, Inc.

Two well established principles of patent law are that: (1) patent law cannot be used to claim laws of nature, natural phenomena and abstract ideas; and (2) patent law can be used to claim inventive ways of applying laws of nature. Mayo examines the uneasy intersection of these two principles in the setting of a diagnostic method for determining the proper dosage of thiopurine drugs for treating autoimmune diseases.

Physicians found it difficult to determine proper dosages of drugs like thiopurine because different patients metabolized medicines at different rates. As a result, the same dosage in different people could be ineffective in one but cause side effects in another. Prometheus was the exclusive licensee of a patented method for determining the proper dosage of the drug by measuring the levels of metabolites in patients blood. It was known that the level of metabolites in blood affected the ability to metabolize a drug and thus the effectiveness of drugs. Prometheus patent taught a method for measuring metabolite levels and, based on refined measurements of the correlation, set thresholds where dosages would be either too high or too low. Mayo used a similar method and Prometheus sued. The district court held that the patent claimed an unpatentable law of nature, but the Federal Circuit reversed.

The Supreme Court agreed with the district court in deciding that the patent claimed a law of nature and nothing more, or at least not enough more. It concluded that the relationship between the concentration of metabolites in blood and a drugs effectiveness was a law of nature, and indeed one that was known. While the patent did set forth an application of the law of nature, a method for determining proper dosages based on measurements of metabolites, the method consist[ed] of well-understood, routine, conventional activity already engaged in by the scientific community; and these steps . . . are not sufficient to transform unpatentable natural correlations into patentable applications of those regularities.

The method for applying the law of nature consisted of measuring levels of metabolite, refining the measurement of the correlation and applying the results to determine when a dosage is too high or low, and adjusting the dosage accordingly. This application of the principle, it concluded, was no more than routine scientific analysis and thus was not inventive enough to be a patentable application.

The case has prompted numerous amicus briefs on both sides of the issue, focusing mostly on whether limits on the patentability of methods for applying natural laws either foreclosed the free use of natural laws by everyone or properly encouraged the more detailed understanding and application of those laws. The Courts comments on those arguments may be helpful to future applicants. First, while courts properly consider whether a method of application is transformative, transformation is only one indicator of patentability. Second, it reasoned that something is no less a law of nature because it, like the correlation between metabolites and dosage effect, is relatively narrow. Even if applying a narrowly-defined natural law may not foreclose much from the public domain, the courts are not in a good position to distinguish the importance or reach of different natural laws. It also rejected the governments argument that any method with additional steps necessarily transforms and therefore should be patentable, countering that such an expansive view would negate the broad principle that natural phenomena are in the public domain.

Chris Mugel practices intellectual property law from the Richmond, Virginia office of Kaufman & Canoles. Christopher J. Mugel