On 13 June 2013, in an opinion authored by Justice Clarence Thomas in Association for MolecularPathology v. Myriad Genetics, Inc., 133 S. Ct. 2107 (2013), the U.S. Supreme Court struck down nine different claims in three patents owned by Myriad Genetics. These composition claims were all drawn to isolated DNA coding for the BRCA1 and/or the BRCA2 genes which are useful in identifying a woman's risk for breast cancer. The Court, in discussing its decision, recognized that each member of the three-member Federal Circuit panel had filed separate opinions as to the question of patent eligibility. 
The unanimous opinion of the Supreme Court quoted extensively from the recent Mayo decision, and confirmed that laws of nature and natural phenomena still constitute exceptions to the generally broad classifications of inventions that qualify for protection under the U.S. patent laws. The opinion furtherexpressed concern that granting patents on such inventions might inhibit innovation and research. 
On the other hand, the Court acknowledged that the proscription against patents on naturally occurring things would be problematic if applied too broadly. The Court also affirmed that "patent protection strikes a delicate balance" between incentives for innovation and patent owner rights. 
The precedent relied on by the Court included a number of earlier cases which involved compositions that included bacteria. The opinion noted that what Myriad had actually achieved was more of a discovery than
an invention, at least with respect to Myriad's composition claims for the isolated BRCA1 and BRCA2 naturally occurring DNA. 
When considering the argument that an isolated DNA segment is different from a natural segment in that its bonds to the rest of the molecule have been severed, the Court found that Myriad's claims were not
expressed in terms of a chemical composition, and contained no limitations directed to how the isolated segment would be chemically different from the naturally occurring segment. 
The fact that cDNA is not naturally occurring, and when synthesized is distinct from the DNA from which it was derived, convinced the Court that cDNA was patent-eligible. 
The Court also highlighted as “important” a few points not implicated by its opinion, including method claims and new applications of knowledge about such naturally occurring genes. Finally, the Court clarified that, “Scientific alteration of the genetic code presents a different inquiry, and we express no opinion about the application of [the law on statutory subject matter] to such endeavors.” 
Practitioners may hereafter accept it as settled law in the U.S. that a composition claim directed to an isolated, naturally occurring DNA segment falls outside the bounds of inventions on which a patent may be granted, and so must look to more creative ways of claiming practical applications of such inventions. 
Looking back on other recent cases dealing with patent eligibility, such as Bilski v. Kappos and Mayo v.Prometheus, the Myriad decision can be seen as another move by the Supreme Court to rein in the Federal Circuit's interpretation of the bounds of patent eligibility. A copy of the opinion is available at