A Glimmer of Hope for Diagnostic Patents (or Perhaps Just a Shimmering Mirage)

March 19, 2018

In the recent, nonprecedential Exergen opinion, a panel of the Federal Circuit considered the subject matter eligibility of a diagnostic method patent claim.  The majority found a diagnostic method to be directed to patent-eligible subject matter, notwithstanding the Supreme Court’s decision in Mayo and the Federal Circuit’s subsequent decision in Ariosa

A representative method claim recited:

A method of detecting human body temperature comprising making at least three radiation readings per second while moving a radiation detector to scan across a region of skin over an artery to electronically determine a body temperature approximation, distinct from skin surface temperature.

The patent in Exergen was based on the discovery of a mathematical relationship between the skin temperature near a patient’s artery, ambient temperature, and core body temperature.  The majority (Judges Moore and Bryson) found that the method claim involved a natural law, but that the steps of the method claim involved an inventive concept that transformed the claim into patent-eligible subject matter. 

The majority asserted that the Exergen claim was different from that in Mayo, where metabolite levels in the blood were measured using methods that “were well known in the art” and “well-understood, routine, conventional activity,” and Ariosa, where fetal DNA in a mother’s blood was measured using methods that were “conventional, routine and well understood.”  In Exergen:

Following years and millions of dollars of testing and development, the inventor determined for the first time the coefficient representing the relationship between temporal-arterial temperature and core body temperature and incorporated that discovery into [a known but] unconventional method of temperature measurement.

That is, the majority appeared to find that the Exergen method was patent-eligible because the newly discovered mathematical relationship was applied in a detecting device in which it had never been applied before. 

The dissent (Judge Hughes) was unable to find light between the outcome commanded by Ariosa and the facts in Exergen.  The dissent noted:

[In Ariosa] the patentee argued its claimed methods of amplifying and detecting paternal cffDNA in maternal plasma supplied an inventive concept because such methods had never been used on maternal plasma samples… Although the claimed methods solved a novel problem, using conventional techniques for a new purpose did not supply an inventive concept that amounted to significantly more than the natural phenomenon to which the claims were directed.

The majority’s argument that the facts in Exergen can be distinguished from Ariosa seems strained – as the dissent points out.  However, this decision may signal a latent belief on the Federal Circuit that Mayo did not require the result in Ariosa – i.e., there may be some contexts in which new discoveries can be applied using known technologies without necessarily being “well-understood, routine, conventional activity previously engaged in by scientists in the field.” 

Exergen Corp. v. Kaz USA, Inc., Nos. 2016-2315, -2341 (Fed. Cir. March 8, 2018)
Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012)
Ariosa Diagnostics, Inc. v. Sequenom, Inc., 788 F.3d 1371 (Fed. Cir. 2015)