A Diagnostic Patent Is Found Patent Eligible At the Federal Circuit

August 4, 2020

In March the Federal Circuit reversed a lower court decision finding Illumina’s patents (U.S.Ps. 9,580,751 and 9,738,931) for diagnosing Down’s Syndrome to be patent ineligible, 952 F.3d 1367 (Fed. Cir. 2020). On August 3, the Federal Circuit denied a petition for rehearing and rehearing enbanc but did issue a new decision adding the term “human-engineered” in several portions of the opinion discussing the separation of fetal DNA from maternal DNA which the inventors had discovered were of different sizes, fetal cell DNA is shorter than the maternal DNA. The inventors recognized that the DNA to be analyzed for genetic aberrations was that of the fetus. The problem was to isolate the small amount of fetal DNA from the maternal DNA so the fetal DNA could be analyzed for genetic aberrations. Prior to the invention there was no known way to distinguish and separate maternal DNA from the tiny fraction of fetal DNA present. The inventors found that by selectively removing DNA having more than 500 or 300 base pairs they could produce a sample where the fetal DNA content in the sample would be enriched and analyzed. The following claim is exemplary:

1. A method for preparing a deoxyribonucleic acid (DNA) fraction from a pregnant human female useful for analyzing a genetic locus involved in a fetal chromosomal aberration, comprising:

(a) extracting DNA from a substantially cell-free sample of blood plasma or blood serum of a pregnant human female to obtain extracellular circulatory fetal and maternal DNA fragments;

(b) producing a fraction of the DNA extracted in (a) by:

(i) size discrimination of extracellular circulatory DNA fragments, and

(ii) selectively removing the DNA fragments greater than approximately 500 base pairs,

wherein the DNA fraction after (b) comprises a plurality of genetic loci of the extracellular circulatory fetal and maternal DNA; and

(c) analyzing a genetic locus in the fraction of DNA produced in (b).

The natural phenomenon according to the dissent was the size difference between maternal DNA and fetal DNA. However, the size difference is not claimed, but is used in the claim to as part of a method preparing DNA fractions from a mother for analysis. Until the inventors discovered the natural phenomenon, it had not been possible to separate fetal and maternal DNA in the sample. The inventors did not claim the size difference but used to prepare a sample for analysis. This use was recognized by the majority as being patent eligible under the Supreme Court decision, citing Diamond v. Diehr, 450 U.S. 175, 185 (1981). The Court went further and noted that the admonishment by the Supreme Court in Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66, 70 (2012) that too broad an interpretation of the 35 U.S.C. § 101 exceptions “could eviscerate patent law.” 

The dissent focused myopically on the discovery of the size difference between maternal DNA and fetal DNA and not on the claim language. The claim does not seek to claim the size of fetal DNA, it uses the size of the fetal DNA to allow for its enrichment in the sample. The use of a natural as being patentable was sanctioned by the Supreme Court in O’Reilly v. Morse, 56 U.S. 62 (1853). In Morse the Court sanctioned the use of the natural law of electromagnetism to send telegrams. As in Morse, here the patent does not claim the natural law to preempt all uses of the DNA size difference but claims a specific use of the difference.


The Federal Circuit is emphasizing that to be patent eligible a claim must use the natural law and not claim it.