The Wisdom of Athena: Justices Criticize Current State of Patent Eligibility for Diagnostic Methods

By David Forman and James Carlson


Some of the most difficult problems in patent law today concern what can be patented.  Patent-eligible subject matter is defined in 35 USC § 101, but the Supreme Court has added some exceptions for abstract ideas, laws of nature, and natural phenomena.  These have led to controversy and uncertainty about what inventions can be protected by patents.  This is starkly illustrated by medical diagnostic methods.  In a recent Federal Circuit decision denying a petition for rehearing en banc[1], all twelve of the Federal Circuit judges agreed that claims to the diagnostic method on appeal ought to be eligible for patentability, yet the patent was found to be invalid as unpatentable under current law.

The patent at issue claimed a method for diagnosing the neuromuscular disease myasthenia gravis by detecting a particular type of autoantibody that was not previously recognized as being correlated with that disease.  In litigation the patent was held to be invalid as unpatentable under the authority of Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. 66 (2012).  In Mayo the Supreme Court found a claimed diagnostic test, directed to the relationship between the concentration of metabolites in the blood and the likelihood that a drug dose will be ineffective, to be merely an unpatentable law of nature.  The court ruled that a claim involving the use of a natural law is unpatentable unless it also contains an “inventive concept,” which must involve more than performance of well-understood, routine, and conventional activities, so that it amounts to “significantly more” than a patent upon the natural law itself.  So far, every patent on a diagnostic method that has reached the Federal Circuit has failed this test for patentability.

And this was the fate of the diagnostic method patent in Athena Diagnostics, Inc. et al. v. Mayo Collaborative Services, LLC.  After a district court found the patent invalid under Mayo, a three-judge panel of the Federal Circuit affirmed for the same reason.  A request to rehear the case en banc led to a uniquely interesting result.  Although rehearing was denied by a vote of 7 to 5, every single judge expressed concern with the current state of the law regarding diagnostic methods, all agreeing that diagnostic method claims should be patent-eligible.

The judges filed eight separate opinions.  Four suggested that some diagnostic methods should be patent-eligible, but that their hands were tied by the Supreme Court Mayo decision.  For example, Judge Hughes wrote that “this is not a problem that we can solve.  As an inferior appellate court, we are bound by the Supreme Court.  I, for one, would welcome further explication of eligibility standards in the area of diagnostics patents.”  Several judges expressed concern that the test for analyzing claims under Mayo (i.e., if a claim involves a law of nature then the remaining elements of the claim must provide an “inventive step”) is in conflict with the principle that a claim must be considered as a whole rather than dissected into its elements.

Four other opinions dissented, arguing that the case should be reheard en banc.  They point out that methods for diagnosing medical conditions are the kind of inventions the patent system should protect—expensive, unpredictable research and development that people pursue in the hope that if they discover something of great medical value, then they will be rewarded for that successful effort with a patent.  They emphasize the vital importance of diagnostic methods to modern medicine.  They suggest that although Mayo has resulted in an apparent per se rule that diagnostic methods are unpatentable, this is too broad a reading of Mayo and that Athena’s claims should be patentable.

The Athena decision illustrates many problems associated with existing 35 U.S.C. § 101 case law.  Critics of the patent system are using the Mayo/Alice framework to address very different issues than what the original statute and the Supreme Court’s decisions were originally intended to address.   For example, Judge Dyk warns that “the doctrines of novelty under § 102, obviousness under § 103, and enablement and written description under § 112 cannot adequately guard against the dangers of overclaiming,” and in turn praises the Mayo/Alice framework for screening out claims that he believes should be patent ineligible.

In contrast to Judge Dyk’s position, Judge O’Malley pointed out that in the past the patent system was seriously hampered when validity was determined by a requirement that a claim must show “invention,” a criterion that was unclear and unmeasurable.   Congress eliminated this problem by entirely abolishing the “invention requirement” and replacing it with 35 USC § 103.  Mayo has restored the abrogated “invention requirement” through the undefined baffling “inventive concept” requirement.

Judge Moore’s dissent is especially enlightening.  Where the majority believes Mayo has implemented a per se rule against diagnostic methods, Judge Moore argues to the contrary.  Judge Moore reiterates the cautionary words of the Mayo opinion that “too broad an interpretation of this exclusionary principle could eviscerate patent law” and subsequently notes that this very thing has happened.  Judge Moore openly contends that the Federal Circuit has “misread Mayo and how it fits within the framework of the judicially-created exceptions to § 101 for laws of nature, natural phenomena, and abstract ideas.”

All of the judges agreed that further guidance is needed from either the Supreme Court or Congress.  Until then it appears that all claims to diagnostic methods will continue to be found to be unpatentable.


[1] Athena Diagnostics, Inc. et al. v. Mayo Collaborative Services, LLC, No. 2017-2508

(July 3, 2019).