On June 12 2015 the Federal Circuit issued an opinion holding that claims directed to a method of detecting paternally inherited cell-free foetal DNA (cffDNA) in maternal plasma or serum were not patent-eligible subject matter under 35 USC § 101.(1)

The opinion for the court was written by Judge Reyna, who was joined by Judge Wallach; Judge Linn wrote a concurring opinion. The underlying subject matter related to a method of amplifying and detecting paternal cffDNA, which is cell-free foetal DNA found in maternal plasma or serum. Detection is useful to determine foetal characteristics, such as gender. Thus, for example, claim 1 was directed to a detection method that comprised the steps of amplifying a paternally inherited nucleic acid from a serum or plasma sample and detecting the presence of the nucleic acid in the sample.

The court evaluated the patent eligibility of the claims using the two-part test set forth in Mayo Collaborative Services v Prometheus Labs, Inc.(2) The court first noted that it was undisputed that the existence of cffDNA in maternal blood is a natural phenomenon. It further noted that the method at issue started with cffDNA taken from a sample of maternal plasma or serum, a natural phenomenon, and ended with paternally inherited cffDNA, also a natural phenomenon. Thus, the court found the claims to be directed to a naturally occurring phenomenon. In support of this conclusion, the court noted that the patent's description of the invention itself stated that the inventors "have demonstrated that foetal DNA is present in maternal plasma and serum", which "may be a useful source of material" for diagnosis. Having found the claims directed to a natural phenomenon, the court then held that the additional process steps in the claims merely employed conventional methods, which the applicant admitted were "a matter of routine for one skilled in the art". Although the court acknowledged that the claimed methods were a significant contribution to science, it concluded that the claims were not patent eligible because they simply applied conventional steps to detect a naturally occurring phenomenon. Even a positive and valuable contribution to science, the court noted, can fall short of being statutory subject matter.

The court also addressed the issue of pre-emption, stating that simply demonstrating the lack of complete pre-emption by pointing to alternative methods of using a natural phenomenon at the centre of a patent claim does not render the claims patent eligible. Linn concurred in the opinion, stating that he was bound by the "sweeping language" of the Mayo two-part test, noting that the Supreme Court's dismissal in Mayo of conventional post-solution steps left no room to distinguish between instances where claimed conventional steps were already being performed and those where they were not – such as in this case.

For further information on this topic please contact Robert H Fischer or Sean Hyberg at Fitzpatrick, Cella, Harper & Scinto by telephone (+1 212 218 2100) or email (rfischer@fchs.com or shyberg@fchs.com). The Fitzpatrick, Cella, Harper & Scinto website can be accessed at www.fitzpatrickcella.com.


(1) Ariosa Diagnostics, Inc v Sequenom, Inc Nos 2014-1139, 2014-1144 (June 12 2015).

(2) 566 US __, 132 S Ct 1289 (2012).

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