The Supreme Court Holds Diagnostic Claims Unpatentable

Craig R. Smith

On March 20, 2012, the Supreme Court delivered a unanimous opinion in Mayo v. Prometheus, a long fought case of critical importance to the diagnostic industry. The decision deals with the patentability of process claims, and in particular diagnostic claims, that rely on “laws of nature, natural phenomena, and abstract ideas.” The decision calls into question the availability of patent protection for certain, and perhaps many, diagnostic methods. The claims at issue in the case relied on a correlation between the level of a metabolite and patient outcome. The Court found the correlation to be a “law of nature” and further, that the claims amounted to an impermissible attempt to patent that law of nature.

The Court held that to be patentable a process claim must have a limitation that prevents it from (improperly) foreclosing all uses of the natural law. In practice this appears to require an additional nonroutine step, or an additional inventive concept (i.e., in addition to the reliance on a law of nature), for patentability. The decision provides that the “machine or transformation” test, which had been relied on twice by the Federal Circuit to find the same claims patentable, cannot trump the “law of nature” exclusion. The Court emphasized the importance of not allowing claims that would act to inhibit further discoveries by improperly tying up the future use of laws of nature. While some issues remain to be resolved in terms of how the USPTO and the courts will apply the decision, the patentability bar is now significantly higher for many diagnostic claims.

Laws of Nature, Without More, Are Not Eligible for Patent Protection

The issue in Prometheus was whether a method claim that draws on a “law of nature” is eligible for patent protection. Section 101 of the patent statute provides that a broad spectrum of inventions is eligible for patent protection, including “any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof.” Though undeniably broad, this spectrum is not without limits. The Supreme Court has long held that Section 101 contains an important implicit exception, namely, that “laws of nature, natural phenomena, and abstract ideas” are not patentable.

The Court has also long recognized that this exception to patent eligibility must itself be limited. All inventions, at some level, apply laws of nature, natural phenomena, or abstract ideas. Without some limitation, the exclusion would, in the Court’s words, “eviscerate” patent law. As the Court noted, its earlier decision in Diehr held that “a process is not unpatentable simply because it contains a law of nature.” Thus, the key question, as framed by the Court, was “whether the claims do significantly more than simply describe these natural relations.” In other words, “do the patent claims add enough to their statements of the correlations to … qualify as patent-eligible processes that apply natural laws?”