Mayo v. Prometheus Laboratories, Inc

One must do more than simply describe a multi-step application of an unpatentable law of nature to transform it into a patent-eligible application of such a law.

Respondent owned a patented process under 35 U.S.C. § 101 that helped doctors determine whether a given dosage level of thiopurine drugs was too low or too high. Petitioner also developed a diagnostic test that measured the dosage level of thiopurine drugs and Respondent sued for infringement of its two patents. The district court granted a motion for summary judgment in favor of Petitioner, finding Respondent’s process patent invalid because the test merely applied laws of nature. After applying a “machine or transformation test” to determine that Respondent had “transformed” the natural law by utilizing a three-step process, the Court of Appeals for the Federal Circuit reversed.

The Supreme Court reversed the Federal Circuit Court and held that Respondent’s process is not patentable subject matter under § 101 because the additional steps added nothing specific to the laws of nature other than what was well-understood, routine, conventional activity, already known by those engaged in this field. The claimed processes of correlating metabolites with drug efficacy are not patentable without adding features to assure the processes were genuine applications of natural laws rather than an effort to monopolize correlative laws of nature. Simply altering conventional steps to the laws of nature in a highly general manner could not make those steps patentable.