"Breakthrough" diagnostic invention deemed unpatentable - where is US patent law heading?

A non-invasive prenatal diagnostic test was recently held to be unpatentable in the US because the Federal Court judges considered the diagnostic test to be a mere natural phenomenon, despite acknowledging that the invention was a “breakthrough” and made “a positive and valuable contribution to science”.  The Ariosa v Sequenom1  decision is just one of several recent decisions concerning the issue as to what type of subject matter is eligible for patent protection.  Future developments on this case are likely to play a key role in shaping the US patent office’s assessment of life science inventions.


What kind of inventions can be patented? “[A]nything under the sun made by man” used to be the mantra of US patent practice regarding patent eligibility of inventions.  However, as previously explained here2, several recent Supreme Court decisions have dramatically altered the way in which the patent eligibility of certain inventions is assessed under US patent practice.  

In the life-sciences field, key decisions include Association for Molecular Pathology v. Myriad Genetics, Inc. (2013)3; and Mayo Collaborative Services v. Prometheus Laboratories, Inc. (2012) (“Mayo”)4.  These decisions prompted the US Patent and Trademark Office (USPTO) to publish in March 2014 new guidance for examination of the subject matter eligibility of claims reciting or involving abstract ideas, natural phenomena or natural products.  The guidance was revised in December 2014 and again in July 2015, including some examples intended to illustrate how to assess patent eligibility. The relevant materials may be accessed here5

Whilst containing some guidance and examples on the assessment of inventions pertaining to “products of nature”, the December 2014 guidance curiously provided very little information regarding the patent eligibility of diagnostic methods.  The July 2015 guidance was expected to fill this void, but it was silent on this point and did in fact not contain any examples pertaining to the life sciences.  

However, the patent eligibility of diagnostic methods was recently considered by the Federal Circuit in Ariosa Diagnostics, Inc. v. Sequenom, Inc. (Fed. Cir. 2015) (“Ariosa”)1

Ariosa Diagnostics, Inc. v. Sequenom, Inc. (Fed. Cir. 2015)

In June 2015 the US Federal Circuit handed down a decision in Ariosa, which concerned the patent eligibility of diagnostic methods.  

Sequenom’s U.S. Patent No. 6,258,5406 (the ‘540 patent) relates to a pre-natal diagnostic test which allows the determination/diagnosis of certain fetal characteristics.  The test is based on the discovery that cell-free fetal DNA (cffDNA) may be detected in serum or plasma obtained from maternal blood.  Accordingly, the inventors developed a method for detecting paternally inherited cffDNA in maternal plasma or serum to determine certain fetal characteristics, such as gender.  A key advantage of this test over previous tests (which involved invasive and therefore risky procedures such as amniocentesis or chorionic villus sampling) is that it is non-invasive, so it has been hailed a “breakthrough”. 

Some of the key claims of the ‘540 patent read as follows:
1. A method for detecting a paternally inherited nucleic acid of fetal origin performed on a maternal serum or plasma sample from a pregnant female, which method comprises:
amplifying a paternally inherited nucleic acid from the serum or plasma sample, and
detecting the presence of a paternally inherited nucleic acid of fetal origin in the sample.

25. A method for performing a prenatal diagnosis on a maternal blood sample, which method comprises:
obtaining a non-cellular fraction of the blood sample,
amplifying a paternally inherited nucleic acid from the non-cellular fraction,
and performing nucleic acid analysis on the amplified nucleic acid to detect paternally inherited fetal nucleic acid.

Sequenom alleged infringement of its ‘540 patent by Ariosa, which led to a counterclaim of invalidity that was first heard by the U.S. District Court for the Northern District of California, which found the claims to be patent ineligible. In June 2015, the Federal Circuit affirmed the decision of the lower court.   

The Federal Circuit court followed the test set out by the U.S. Supreme Court in Mayo, and reasoned that the claims of the ’540 patent are nothing more than the detection of a natural phenomenon, i.e., the presence of cffDNA in maternal plasma and serum, in combination with well understood, routine, and conventional activity, such as detecting the cffDNA by polymerase chain reaction (PCR).

Interestingly, the judgement includes an opinion by Judge Linn, in which he heavily criticises the Mayo test, arguing that the language of the test is too broad.  He makes it clear that his decision in Ariosa would have been different, had he not been “bound by the sweeping language” of the Mayo test.  In what could be interpreted as a plea for a change in the law, he concludes that the Ariosa case “represents the consequence -- perhaps unintended -- of that broad language in excluding a meritorious invention from the patent protection it deserves and should have been entitled to retain."


The Ariosa decision seems to set the bar for patent eligibility higher than ever.  Judge Linn felt that the Mayo test is too broad, but that he was forced to apply it to Ariosa.  However, it could be argued that in Ariosa the court did in fact apply Mayo too broadly, rather than taking the opportunity to interpret Mayo more narrowly.  

In Ariosa, the court broke down the claims into several elements, determining cffDNA to be a natural phenomenon and its detection to be a routine step.  What the court failed to do is to consider the claimed invention as a whole.  Prior to the invention, DNA detection such as PCR on maternal plasma or serum was not carried out.  Whilst a DNA detection step per se is conventional, it was not in any way conventional to apply it to maternal plasma or serum.    

If Ariosa is followed, then it is difficult to see how any inventions in the medical diagnostics field could be patent eligible in the US, unless they involve a non-conventional detection method (such as detection via a novel antibody).  


Although the Ariosa decision issued before the July 2015 guidance was published, the guidance did not comment on this decision, other than pointing out that it might be subject to further judicial developments.  
Sequenom have signalled that they will not give up without a fight.  They have asked for reconsideration of this case by the Federal Circuit  en banc (by all of the judges of the Federal Circuit).  In a move that illustrates how strongly the industry yearns for clarification of the law, twelve groups have separately filed amici briefs (which is information filed by someone who is not a party to the proceedings) in support of Sequenom’s petition for reconsideration en banc.  A decision as to whether the case will be heard is expected later this year, and we will keep you informed of further developments.  


1)  Ariosa Diagnostics, Inc. v. Sequenom, Inc. (Fed. Cir. 2015)

2)   Encouraging new guidance on the patentability of nature-based products in the US

3) Association for Molecular Pathology v. Myriad Genetics, Inc. (2013)

4) Mayo Collaborative Services v. Prometheus Laboratories, Inc. (2012)

5) 2014 Interim Guidance on Subject Matter Eligibility, including July 2015 update

6) US 6,258,540

Barbara Rigby, Associate