Diagnostic Method Claim in the US

(By George Wu) Another important case concerning biotechnology was decided last year at the US Supreme Court: Mayo Collaborative Servs. v. Prometheus Laboratories, Inc., 132 S. Ct. 1289 (2012)

Prometheus Laboratories (“Prometheus”) had obtained a patent for a method of determining the optimal dosage of the drug thiopurine, which is used to treat auto-immune disorders.  The use of thiopurine in the treatment of disease was not a new discovery, but the use of the drug had been made difficult by the fact that thiopurine is metabolized at different rate in different people.  Accordingly, the same dosage could be too low to be efficacious in one patient, while too high and toxic in another patient.  Prometheus made the discovery that by assaying for the metabolites of thiopurine, the rate of metabolism could be determined and the dosage could be adjusted according to the patient.

Right away, Prometheus sought and received a patent for the process.  Prometheus then started to market a Thiopurine Metabolites Test, which the Mayo Clinic (“Mayo”) initially purchased and utilized.  However, in 2004, Mayo decided to start making and selling its own test relying on a slightly modified patented process.

Accordingly, on June 15, 2004, Prometheus initiated legal action against Mayo for patent infringement in the United States District Court for the Southern District of California.  The District Court found that Mayo’s test was an infringement on the Prometheus patent.  However, the District Court granted summary judgment in favor of Mayo, deciding that Prometheus’ patent claims were unpatentable due to the fact that they cover natural phenomena.  The District Court asserted that the inventors did not “create” the correlation between the rates of metabolites of the thiopurine and the effective dosage of thiopurine.  The District Court further declared that the correlation was based on a natural body process that exists in the patient population, and thus, the process that Prometheus had discovered was the work of nature.

Prometheus then appealed to the Court of Appeals for the Federal Circuit.  The Federal Circuit reversed the decision by the District Court by applying the definitive machine-or-transformation test.  The Federal Circuit considered the steps of administering thiopurine and drawing blood to measure the metabolites are both related to the physical transformation of the human body, and thus, the process is patentable under the machine-or-transformation test.  However, soon after this decision, the Supreme Court in the decision in Bilski v. Kappos, 130 S. Ct. 3218 (2010), ruled that the machine-or-transformation test was not definitive.  The Supreme Court granted certiorari and vacated the Federal Circuit decision.  The case was then remanded to the Federal Circuit in light of the Bilski.

On remand, the Federal Circuit again held that the method claims for Prometheus were patentable.  The Federal Circuit considered that even if the machine-or-transformation was no longer an exclusive test, but it still served as an important clue, and that the physical transformations occurring in the human body makes the claims patent eligible.

After the decision by the Federal Circuit, Mayo again appealed and was granted certiorari by the Supreme Court.  The Supreme Court reversed holding that the method claims in the Prometheus patents effectively claimed the underlying laws of nature themselves, and thus, they are not patent eligible.  Thus, in order to be patent eligible, a method claim that applies natural laws must comprise additional elements other than what were well-understood, routine, and conventional activities.

Central to the Supreme Court’s deliberation was whether Prometheus added enough elements to their correlative effect in their method claims to qualify as patent eligible processes that apply natural laws.  The Court concluded that they had not.

In conclusion, a law of nature is not patentable as a process.  The application of that newly discovered law is also normally unpatentable if the application merely relies on elements already known in the art.  Lastly, the application of the law must be significant, but not too broadly so as to preempt use of the nature law.

If you have any questions about this article or any issues regarding intellectual property protection in the United States, please feel free to contact me atgeorge.wu@huschblackwell.com.

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