Alert June 24, 2015

Federal Circuit Holds Medical Diagnostic Method Patent Invalid as Claiming Ineligible Subject Matter


On June 12, 2015, the Federal Circuit, applying recent Supreme Court decisions, held the medical diagnosis method claims at issue in Ariosa v. Sequenom invalid as directed to subject matter that is not eligible for patenting. This holding calls into question many method patents relating to medical diagnostics.


In two recent cases, Mayo v. Prometheus and Alice v. CLS Bank, the Supreme Court established a two-part test for determining eligibility for patenting. In step one, the court asks whether the claim is directed to a patent-ineligible concept, such as a law of nature or an abstract idea. In step two, the court asks whether the claim includes other limitations providing an “inventive concept” such that the claim is directed to “significantly more” than the patent-ineligible concept itself.

In Mayo, the claims related to a method of optimizing therapeutic efficacy by determining the level of a particular metabolite of the drug in the subject; the level of the metabolite would indicate whether the amount of the drug to be administered should be increased or decreased. The Supreme Court held that the claims were directed to patent-ineligible laws of nature—the relationships between metabolite levels and optimal drug dosage. The Supreme Court concluded that the drug, its administration, and tests for its metabolite were all known and routine prior to the alleged invention and therefore held that the claims were invalid because they were not directed to significantly more than the patent-ineligible natural correlations between metabolite levels and drug dosages.

The Ariosa Holding

The claims at issue in Ariosa involved methods for prenatal diagnosis of a fetus by testing for a particular type of paternally inherited DNA in the mother’s blood. The Federal Circuit found the claims patent ineligible.  It reasoned that the presence of this paternally inherited fetal DNA in a maternal sample is a natural phenomenon and therefore not itself patent-eligible under the first step of the Mayo/Alice test. It also decided that  amplifying and detecting DNA are routine, conventional steps and thus did not constitute a sufficient inventive step to render the claimed methods patent eligible under the second step.

The patent holder had made two key arguments distinguishing the Ariosa claims from those at issue in Mayo, both of which the Federal Circuit found insufficient to establish patent eligibility. First, it was undisputed that it had not previously been known that this paternally inherited fetal DNA could be detected in a maternal sample and so no such testing had been done; indeed, maternal plasma had previously been “routinely discarded” when attempting to test for fetal characteristics. In Mayo, on the other hand, the administration of the drug and testing for its metabolite were both routine and conventional, with the only alleged invention being the identification of the naturally occurring correlation between metabolite levels and appropriate drug dosages. The Federal Circuit rejected this distinction as insufficient to establish patentability.  Instead, the Court concluded broadly that a method claim that “starts and ends with a naturally occurring phenomenon” fails to disclose patent eligible subject matter “if the methods themselves are conventional, routine and well understood applications in the art.” Because the techniques used in the Ariosa claims to detect and amplify DNA were not new, the Federal Circuit found the method claims ineligible for a patent.

Second, the patent holder in Ariosa argued that the method claims at issue did not preempt all uses of the particular DNA and thus did not create the preemption problem underlying the Supreme Court’s patent eligibility test. The Federal Circuit rejected this distinction as well, holding that “the absence of complete preemption does not demonstrate patent eligibility.”

Likely Impact

This decision highlights the vulnerability of diagnostic method patent claims under the Supreme Court’s broad two step test for patent eligibility. As Judge Linn noted in a concurring opinion, this case illustrates “the consequence—perhaps unintended—of [the Supreme Court’s] broad language in excluding a meritorious invention from the patent protection it deserves and should have been entitled to retain.” It may take legislative action to restore patent eligibility in the field of medical diagnostics.