U.S. courts and the U.S. Patent and Trademark Office have been wrestling with the fundamental question of what is and is not eligible subject matter for a patent in the United States. 35 U.S.C. § 101 serves as the statutory threshold for eligibility, but various Supreme Court decisions in the past decade have severely limited patentable subject matter. Under the Mayo/Alice framework, courts first ask if the subject matter of an invention is directed to ineligible subject matter; if so, courts then look for an application that transforms the invention into patent eligible subject matter.

The Court of Appeals for the Federal Circuit has recently taken a broad interpretive view of Mayo/Alice as it relates to diagnostic method patents. This year, the Federal Circuit has signaled a willingness to find valid diagnostic method claims that recite a practical application of diagnostic test results in addition to ineligible, Mayo-like diagnostic observations. In Vanda Pharma v. West-Ward Pharma (2018)), the claims at issue are directed to an application of the results of diagnostic testing. Shortly following Vanda, the USPTO released guidance suggesting diagnostic method patents may be salvaged by including ‘‘apply it’’ language to diagnostic results.

Here, we explore the evolving law of § 101 eligibility of diagnostic method claims in light of Vanda. We also highlight indicia that congressional action on subject matter eligibility may be forthcoming.

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