Implications of the Recent Mayo Case on Patentable Subject Matter

Last December, I wrote a series of posts about what was – and remains – a hot topic in patent law:  patentable subject matter under 35 U.S.C. § 101.   The law on patentable subject matter often boils down to whether the invention is so abstract or such a product of nature that the invention is not patent eligible even if it meets the other statutory requirements of being new, not obvious and useful.  Since those posts, the Supreme Court has issued another decision further limiting patentable subject matter in Mayo Collaborative Servs. v. Prometheus Labs., Inc.  I believe that patent eligible subject matter is going to continue to be a thorny issue for many software, medical diagnostic and biotechnology inventions.  However, I believe that in the majority of cases involving mechanical devices, medical devices, and new chemical compositions, patent eligibility under § 101 is going to be a non-issue, that is most inventions in these fields will readily qualify under § 101.

In Mayo, the invention related to the discovery that a particular concentration of drug metabolites in the blood should be targeted by doctors when they prescribe a particular class of autoimmune drugs.  (A drug metabolite is a chemical formed when the body digests – i.e., metabolizes – a drug.  In the pharmaceutical industry, it is extremely common to identify metabolites and their concentrations during clinical testing).    In particular, each claim of the plaintiff’s patent included (1) an administering step that instructed a doctor to administer the drug to his patient (2) a determining step that told the doctor to measure the resulting metabolite levels in the patient’s blood and (3) a wherein step that described the target metabolite concentration and informed the doctor to adjust the patient’s dosage if the patient’s metabolite levels were outside of the target concentration.

Addressing the patent eligibility issue, the Court repeated the commonly recited proposition that laws of nature, natural phenomena and abstract ideas are not patent eligible.  The court then found that the heart of the invention — namely, the discovery of the relationship between the concentrations of certain metabolites in the blood and the likelihood that the prescribed drug dosage would prove ineffective or cause harm — was simply a law of nature.  Further, in the Court’s view, the three recited steps failed to “add enough” to render the claimed method a patent-eligible process.  The Court found that the first step referred to a pre-existing audience, namely, doctors that already administer the drugs, the second step merely told doctors to measure metabolites in the blood, and the wherein step merely informed doctors about the law of nature.  Accordingly, the Court held that the claimed process was not patent eligible.

In my view, the Mayo decision is problematic for a few reasons.  For example, while it’s easy to say that laws of nature, natural phenomena and abstract ideas are not patent eligible, it’s often difficult to apply this rule in practice and conclude when an invention “adds enough” to render a claimed method patent eligible.  Indeed, perhaps for this reason, the Federal Circuit had crafted a machine-or-transformation patent eligibility test in which a claimed process was generally patent-eligible if it was implemented with a machine or transformed matter, and patent ineligible if it was not implemented with a machine or transformed matter.  Additionally, in my view, the proper way to strike down the patent in Mayo was on obviousness grounds.  It has been known for decades that it’s important to measure drug metabolite levels and at the time of the invention at issue in Mayo, scientists knew that the metabolites at issue were correlated with drug safety and effectiveness.  Though the particular target levels were not known, the methods to test metabolite levels were old and there was clearly a motivation to use these known methods to find the target levels.

It goes without saying that how the lower courts will apply Mayo will be important for companies in the software, diagnostic and biotechnology industries.


This article is for general information only. The information presented should not be construed to be formal legal advice nor the formation of a lawyer/client relationship.

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Shane Cortesi

Shane Cortesi

Shane Cortesi is a Nashville-based attorney who advises inventors, artists, and entrepreneurs on protecting and licensing their inventions, artwork, and other intellectual property. A 2005 graduate of The George Washington University Law School, Shane also holds a Master’s in Biotechnology from Northwestern University and a Bachelor’s in Zoology from Miami University.

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