MX: Patentability of Medical Method Patents After Bilski

Posted by Heather Thompson on November 24, 2010

The Supreme Court’s decision in Bilski vs Kappos rejects the Federal Circuit’s machine-or-transformation test as the exclusive test for patentability. How will the decision affect patentability determinations for medical methods?

The Supreme Court’s much anticipated decision in Bilski vs Kappos, issued on June 28, 2010, is read as rejecting the Federal Circuit’s machine-or-transformation test as the exclusive test for patentability for methods. Many in the medical device field now wonder how the decision affects patentability determinations for medical methods, and in particular diagnostic methods and methods of treatment.

Medical Methods Under the Federal Circuit’s Machine-or-Transformation Test

Under the formerly exclusive machine-or-transformation test, for a method to be patentable under 35 USC § 101, the Federal Circuit required that a method either be tied to a particular machine or apparatus, or transform a particular article into a different state or thing. Medical methods involving the use of a particular medical device or apparatus easily satisfied the machine prong of the Federal Circuit’s exclusive machine-or-transformation test; however, courts seem to have more difficulty in applying the transformation prong to medical methods lacking such a device. Medical methods lacking a device typically include methods of treatment and diagnosis, often involving method steps such as administering a drug, testing, gathering, and correlating data, or manipulating tissue.

Before the Bilski decision, the boundaries of the transformation prong of the test as applied in the general life science field were bracketed by two decisions of the Federal Circuit: Prometheus vs Mayo, 581 F.3d 1336 (Fed. Cir. 2009) and Classen vs Biogen, 304 Fed. Appx. 866 (Fed. Cir. 2008) (unpublished). In Prometheus, the Federal Circuit effectively considered the diagnostic method as part of an overall method of treatment, and held that methods of treatment “are always transformative when a defined group of drugs is administered to the body.” Specifically, the Federal Circuit found that physical changes in drug metabolites and manipulation of a sample were transformative, thus patentable under § 101. In Classen, the Federal Circuit affirmed a lower court ruling that a broad method of determining the effectiveness of an immunization schedule by immunizing a treatment group and comparing the immunized treatment group with a control group did not meet either the machine or transformation requirements, thus was not patentable under §101.

The Supreme Court’s Rejection of the Federal Circuit’s Machine-or-Transformation Test As an Exclusive Test

In Bilski, the Supreme Court held that the machine-or-transformation test was inappropriate as an exclusive test for determining patentable subject matter. The Court noted that the Patent Act was intended to encompass “new and unforeseen inventions” that may not satisfy the dated requirements of the exclusive machine-or-transformation, which may be more aptly applied to inventions of the Industrial Age. The Bilski Court further noted that “new technologies may call for new inquiries,” even referencing “advanced diagnostic medicine techniques” as one such technology. Although the Court declined to expand specifically on the patentability of such techniques, the context can be read to support the possibility that medical diagnostic techniques that do not survive the machine-or-transformation test may still constitute patentable subject matter. The Court held the machine-or-transformation test may be an important indicator of patentable subject matter; however, the Court explicitly recognized that methods not satisfying the machine-or-transformation test might still be patentable, while further reiterating that methods directed solely to abstract ideas were not patentable under § 101.

The Supreme Court remanded both Classen and Prometheus back to the Federal Circuit in light of Bilski. However, there is no indication in Bilski that methods of treatment should not continue to be considered “transformative” in nature. If anything, the decisions on remand might clarify the boundary of what is considered not patentable subject matter for being drawn to an abstract idea.

PTO Response To Bilski

On July 27, 2010, the PTO issued the Interim Guidance for Determining Subject Matter Eligibility for Process Claims in View of Bilski vs Kappos, superseding all conflicting previous guidance on determining patentable subject matter under § 101 (available at The guidance requires the examiner to establish a prima facie case of patent-ineligibility and provide clear rationale in support of such a determination. The PTO guidelines also adopted the following four nonexclusive factors for an examiner to consider when determining patent eligibility of method claims as follows:1

  • “Whether the method involves or is executed by a particular machine or apparatus.”
  • “Whether performance of the claimed method results in or otherwise involves a transformation of a particular article.”
  • “Whether performance of the claimed method involves an application of a law of nature, even in the absence of a particular machine, apparatus or transformation.”
  • “Whether a general concept (which could also be recognized in such terms as a principle, theory, plan or scheme) is involved in executing the steps of the method.”

While the involvement of a machine, transformation, or application weighs in favor of patent-eligibility, the presence of a general concept may be a clue that the claim is drawn to an abstract idea and weighs against patent-eligibility. The guidelines further instruct examiners to consider the claim as a whole and that if the presence of a machine, transformation, or application in a claim is merely an extrasolution activity or contributes only nominally or insignificantly to the execution of the claimed method, such a finding weighs against patent-eligibility. The guidelines appear to move away from using the Federal Circuit’s machine-or-transformation test as a threshold for determining patentability by seemingly placing the four factors on equal footing, while reinforcing the concept that a method cannot solely be drawn to an abstract idea in the description of each factor.

Application of Bilski To Medical Method Claims

According to the PTO’s guidelines, the machine-or-transformation test is no longer a threshold test. In applying the PTO’s four factors, though, the machine and transformation factors may be clearer and more-predictably applied than the application and general concept factors. Thus, it may still be advantageous for methods of treatment and diagnostic methods to include features that satisfy the machine or transformation factors. Accordingly, when drafting medical method claims that lack a specialized therapeutic or diagnostic device, applicants should consider including claims directed to methods of treatment and emphasizing the transformational aspects of the method.

Transformational aspects that may be incorporated into at least some of the claims may involve physical acts that do not solely rely on natural phenomena or abstract principles, and that are dependent on or responsive to more general concepts or information. For example, one such physical act may include a treatment-related step taken in light of diagnostic information, such as “providing a warning,” “altering a therapy,” or even “providing the output so as to allow a therapy to be altered.” Applicants should also consider including steps that highlight the method’s transformative aspects and remove the method from a series of abstract mental steps or observations. Of course, all the claim elements will need to be adequately supported by the specification. The requirements for enforcing the patent against potential infringers should also be considered when drafting medical treatment or diagnosis patents, so that the claim language is tailored for the nature of the relevant market and products being protected.

Additionally, even in the absence of a particular machine or transformation, claims may still be patentable as long as they are not solely drawn to an abstract idea. Thus, clear indicators that the method involves a particular medical indication and is not solely directed to a general concept or an abstract idea can reinforce claim patentability. For broad diagnostic patents, such indicators may include identifying a patient’s particular medical condition or prescribing a specific treatment regimen. Medical treatment claims may also, for example, include tissue-response clauses, optionally with varying levels of specificity as to the therapeutic results, from quite broad (“…applying the energy to remodel tissue,” or “inhibiting a deleterious tissue response by…”) to much more specific (“…wherein the RF energy vaporizes the target tissue”). Support and enforcement issues should again be carefully considered in selecting claim language.


1. Interim Guidance for Determining Subject Matter Eligibility for Process Claims in View of Bilski v. Kappos, 75 Fed. Reg. 43,922, 43,925 (July 27, 2010).

Ken Shurtz is an associate at Townsend in the Palo Alto–CA office. He can be contacted at Mark Barrish is a partner in Townsend’s Palo Alto office and leads the firm’s medical and surgical devices group. He can be contacted at

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