On August 16, the United States Court of Appeals for the Federal Circuit (the “USCAFC”) rendered its decision in the Myriad case1 after the case was remanded back to it by the U.S. Supreme Court for re-determination in light of that court’s recent decision in Mayo Collaborative Services v. Prometheus, Inc. (“Mayo”).2  In the Myriad decision, the court concluded that human-made compositions of matter, such as isolated DNA molecules, as well as screening methods incorporating such human-made compositions of matter are patent-eligible subject matter. It also affirmed the District Court’s finding that Myriad’s diagnostic methods involved only abstract mental steps and therefore were not eligible for patent protection. This much-awaited decision provides additional guidance to patent owners and applicants on the eligibility of biological products and personalized medicine claims in the United States.

Amongst other issues, the USCAFC was asked to determine if fifteen claims from seven patents3 assigned to Myriad were drawn to eligible subject matter. In particular, the claims at issue fell into three categories: compositions of matter (isolated DNA); diagnostic methods; and screening methods. Prior to addressing each claim category, the court reviewed the law relating to patentable subject matter as set out in § 101 of the Patent Laws.4 The court noted that while § 101 has been construed broadly, it is not unlimited and excludes, on a judicial basis, laws of nature, natural phenomena and abstract ideas.5 The court was also careful to note that issues other than eligible subject matter, such as claim breadth, novelty and obviousness, were not before it and therefore not considered.6

Composition of matter: isolated DNA molecules

The court first addressed whether isolated DNA molecules are eligible for patent protection. This portion of the decision was split, with two members of the court, in separate reasons, finding that the claimed isolated DNA molecules did constitute patent-eligible subject matter and a third member of the court, in a dissenting opinion, finding that the isolated DNA molecules did not constitute patentable subject matter.

Writing for the court, Circuit Judge Lourie found that isolated DNA molecules are not found in nature, but rather are “a product of human ingenuity”7 markedly different from the DNA found in nature.8 The court also held that a composition of matter is not a law of nature per se9 even though any and all human-made compositions of matter do follow a law of nature.10 Finally, the majority pointed to the United States Patent and Trademark Office’s (the USPTO’s) long-standing practice of granting patents for isolated DNA molecules, the resultant “settled expectation” of the biotechnology community, and the associated adverse effects on innovation that a holding of ineligibility might cause, as a basis to hold that any exception to eligibility for isolated DNA must come from Congress and not the courts.11 

Diagnostic methods: methods of comparing and analyzing DNA sequences for determining disease susceptibility

As previously articulated in the Mayo Supreme Court decision, diagnostic methods encompass natural laws and, in order to be considered patent eligible, must claim more than the natural law and its application.12  The diagnostic claims in issue claimed methods of “comparing” or “analyzing” certain gene sequences with a view to identifying a pre-disposition to cancer. The court unanimously held that the diagnostic method claims in issue were not directed to patent-eligible subject matter. Relying on the Supreme Court’s ruling in Mayo and Bilski, the court held that since the diagnostic claims solely comprised abstract mental steps (either comparing or analyzing the sequences of the genes), they were not directed to patent-eligible subject matter.13  The court noted that an abstract idea (such as a comparing step) may be present in a patent-eligible process, but that a process solely relying on an abstract idea cannot be considered patent eligible.14 The court further noted that the diagnostic claims failed to recite physical embodiments (e.g., sample processing, sequencing, etc.) that may have been useful in supporting patent eligibility.15

Screening methods: methods for screening potential cancer therapeutics

Finally, the court unanimously determined that a claimed screening method incorporating patent-eligible DNA molecules (expressed by transgenic host cells) was eligible for patent protection. The court distinguished the claim in issue from those considered by the Supreme Court in Mayo, and held that by requiring a human-made transgenic host cell (expressing the human-made DNA molecule) the claim claimed more than mere abstract mental steps or the simple application of a law of nature and therefore was directed to patent-eligible subject matter.16 Although the claim included abstract mental steps, it was still based on the use of a patent-eligible composition of matter (e.g., non-naturally occurring transformed cell).17 The court indicated that the transformed human-made nature of the underlying subject matter rendered the claimed subject matter eligible for patent protection.18


This decision confirms the USPTO’s long-standing practice of granting patents for human-made DNA preparations and may support the patentability of other biotechnology inventions such as bacterial enzymes, plant-derived biologics and other industrially and medically useful substances. The court affirmed that care should be taken not to read into the Patent Laws limitations and conditions on patentability not expressed by Congress. Finally, if necessary, it is the role of Congress, not the courts, to overturn the USPTO’s long-standing practice in favour of a rule treating isolated DNA differently from other compositions of matter.