American Journal of Law & Medicine

Prometheus and Bilski: pushing the bounds of patentable subject matter in medical diagnostic techniques with the machine-or-transformation test.

If nature has made any one thing less susceptible than all others of exclusive property, it is the action of the thinking power called an idea, which an individual may exclusively possess as long as he keeps it to himself; but the moment it is divulged, it forces itself into the possession of every one, and the receiver cannot dispossess himself of it. (1)


Patent law has come a long way from the bare assertion that "[i]t is self-evident that thought is not patentable." (2) The Federal Circuit recently upheld the patentability of a process for calibrating drug dosages that incorporates a mental step as one of its components. (3) However, the degree to which patent law will tolerate the presence of mental steps historically has fluctuated, and it is now being challenged by several recent lawsuits involving patents that incorporate these steps to varying degrees. A recent spate of opinions from both the Federal Circuit and the Supreme Court has pushed to the forefront a revived debate over what types of applications incorporating mental steps should be recognized as patentable subject matter. The nature of the patents at issue in these cases has complicated the task of delineating a coherent rule for the subject matter doctrine, when the applications attempt to reserve exclusive rights for inventions in a controversial and rapidly-developing field of medicine: diagnostic techniques.

To find the proper place for medical diagnostic techniques in the subject matter doctrine, it is crucial to underscore that the underlying tenets of the patent law and the practice of medicine often push in different, and sometimes contradictory, ways. For example, a patent provides its holder with the exclusive rights to an invention for a period of twenty years. (4) Medical ethics, however, stress the need to openly share discoveries and advances in the field to provide the best care to patients as soon as possible. (5) Thus, although patent law, through various requirements, such as enablement, (6) allows persons skilled in the art to learn the new claimed technology, others must either abstain from using that technology for twenty years, pay a license fee, or risk an infringement suit. For physicians, who have an ethical obligation to act in the best interests of their patients, this result forces them either to forego utilizing possibly life-saving treatment to the detriment of their patients, or to face potentially substantial financial consequences in the form of licensing fees or damages.

In contrast to this tension between medicine and patent law, a patent's exclusivity provides inventors with a strong incentive to research and develop new technology, which in turn benefits the medical community, most notably by improving the quality of available medical care. Yet this incentive, however strong it may be, does not justify a boundless expansion of the patent property right:

   [M]edical associations recognize that healthcare-related patents
   can enhance the provision of high-quality and cost-effective
   medical care. The financial incentive that patents offer supports
   the expensive and uncertain research required to identify, test,
   and gain approval for new pharmaceutical products, medical devices,
   diagnostic testing kits, and so forth. In this respect, the patent
   system has served patients and the medical profession well.

   Patents on basic scientific principles underlying medical care,
   however, do not have these salutary effects. Such patents raise
   ethical concerns for physicians, threaten to stifle innovation and
   raise the costs of medical treatment, and erode the quality of
   patient care by limiting the knowledge physicians may use to
   diagnose and treat their patients. (7)

The deleterious effects of patenting basic scientific principles animate the primary concerns in the recent litigation over patentable subject matter. In particular, the medical community has closely watched case law development regarding medical diagnostic techniques involving certain "correlation" claims, which some argue encompass nothing more than basic scientific principles. For example, in Prometheus Laboratories, Inc. v. Mayo Collaborative Services, the patents at issue involved a process for correlating levels of certain metabolites resulting from administering thiopurine drugs to a patient with potential toxicity in that patient. (8) This relationship was important because it allowed physicians to identify patients who might have particularly adverse reactions to certain levels of thiopurine drugs, whereas lacking prior medical knowledge on proper dosage levels caused doctors to cautiously prescribe low doses out of toxicity concerns. (9)

Whether this type of correlation process is eligible for patent protection impacts both present-day use of diagnostics and future expansion in personalized medicine. (10) A number of medical associations, writing as amici in Prometheus, described the field of personalized medicine as the following:

   Personalized medicine ... aims to achieve optimal medical
   outcomes by helping physicians and patients choose the disease
   management approaches likely to work best in the context of a
   patient's genetic and environmental profile. Such approaches may
   include genetic screening programs that more precisely diagnose
   diseases and their sub-types, or help physicians select the type
   and dose of medication best suited to a certain group of
   patients. (11)

The recent debate concerns a particular aspect of personalized medicine--process claims involving correlation--and not the patentability of products, such as the drugs themselves or new diagnostic testing kits. (12) With this specific frame of reference in mind, the impacts that Prometheus will have on pharmacogenetics--a field involving the study of genetic variation to determine individual drug responses--become readily apparent. (13) If correlation steps such as those at issue in Prometheus are unpatentable, future inventions involving correlations of particular genetic sequences to certain drug responses potentially face a higher hurdle in obtaining patent protection. This uncertainty, in turn, poses the risk of a decreased financial reward for research that in some cases costs hundreds of millions of dollars and spans over a decade. (14)

To help understand the viability of patenting diagnostic claims, this note will extensively analyze the Federal Circuit's treatment of the process patents at issue in Prometheus. The machine-or-transformation test will provide both an analytic framework to dissecting these claims and a means to discuss various other rules applicable to the subject matter doctrine, such as the fundamental principles limitation. Ultimately, this note concludes that diagnostic techniques have properly emerged from the recent line of subject matter challenges as a viable candidate for patentability, despite the historical hesitancy to afford protection to claims incorporating mental steps.

Part II of this note begins with a basic background of patentable subject matter and some of its historical justifications. Part III discusses limits to this doctrine that are pertinent to diagnostics, including the fundamental principles limitation and the mental steps doctrine. Part IV provides an introduction to the machine-or-transformation test as background to this note's main focus in Part V on the application of this test to the process patents in Prometheus. This analysis will facilitate an understanding of the particular claims at issue in Prometheus, how they relate to the subject matter doctrine generally, and how similar diagnostic claims might be reviewed by courts for patentability. Part VI will discuss the Supreme Court's most current statement of the subject matter doctrine in Bilski v. Kappos. (15) Finally, part VII will offer closing remarks on how Bilski might affect the Federal Circuit's consideration of Prometheus on remand, in addition to some of the policy considerations at stake for future diagnostic claims.


A patent gives its holder the right to "exclude others from making, using, offering for sale, or selling the invention." (16) Patent law must balance, inter alia, two policy concerns: being expansive enough to provide inventors the incentive to create, and being restrictive enough to ensure that innovation is not handcuffed by patent rights. (17) The Constitution delegates the task of achieving this delicate balance to Congress, (18) which has established a statutory scheme with several basic requirements to obtain a patent: the invention must be useful, (19) novel, (20) non-obvious, (21) sufficiently described and enabled, (22) and of a kind eligible for patent protection. (23) This final requirement is referred to as "patentable subject matter."

As originally governed by the Patent Act of 1793, patentable subject matter included "any new and useful art, machine, manufacture or composition of matter, or any new and useful improvement." (24) In 1952, Congress enacted the current subject matter provision, [section] 101, changing the 1793 standard by replacing "art" with "process." (25) Section 100(b) of the Patent Act defines "process" as a "process, art or method, and includes a new use of a known process, machine, manufacture, composition of matter, or material." (26) Further, the Supreme Court has defined "process" as "an act, or a series of acts, performed upon the subject-matter to be transformed and reduced to a different state or thing." (27)

In discussing [section] 101, the Supreme Court has stated that its four categories (process, machine, manufacture, and composition of matter) encompass "anything under the sun that is made by man." (28) Also, the text of [section] 101 states that "any" patent falling within one of these categories satisfies the subject matter requirement. (29) The Supreme Court's gloss and the text of 101, coupled with the fact that the four categories themselves are extremely broad, require close judicial scrutiny of patent applications to define a scope for subject matter that will both encourage innovation yet preserve essential tools of creation for future inventors. The following section describes some of the basic rules courts have fashioned in attempting to strike this balance, particularly with respect to what constitutes a "process" under [section] 101.



One of the earliest and most elemental limits on the subject matter doctrine is that fundamental principles are unpatentable. (30) An early Supreme Court case stated that "a principle is not patentable. A principle, in the abstract, is a fundamental truth; an original cause; a motive; these cannot be patented, as no one can claim in either of them an exclusive right." (31) The Court in Diamond v. Chakrabarty further elaborated that "laws of nature, physical phenomena, and abstract ideas" are three categories of subject matter that fall outside the protections of [section] 101. (32) Thus "Einstein could not patent his celebrated law that E = [mc.sup.2]; nor could Newton have patented the law of gravity. Such discoveries are 'manifestations of ... nature, free to all men and reserved exclusively to none.'" (33)

The generally accepted justification for this doctrine is to keep the basic means of scientific research available. (34) The Constitution mandates that patents should "promote the Progress of Science and useful Arts." (35) Fundamental principles do not receive protection because they are "part of the storehouse of knowledge of all men," (36) a source of common knowledge from which future inventors may draw. (37) Laws of nature and physical phenomena are not patentable because they occur within nature, and hence humans cannot "invent" them. (38) Finally, "abstract ideas constitute disembodied concepts or truths which are not 'useful' from a practical standpoint standing alone, i.e., they are not 'useful' until reduced to some practical application." (39)

A famous early case illustrating this limitation on patentable subject matter is O'Reilly v. Morse, in which the Supreme Court considered the patentability of Samuel Morse's electromagnetic telegraph. (40) The Court evaluated, among other things, the patent's eighth claim, which began as follows: "Eighth. I do not propose to limit myself to the specific machinery or parts of machinery described in the foregoing specification and claims; the essence of my invention being the use of the motive power of the electric or galvanic current, which I call electro-magnetism...." (41) This claim encompassed "the exclusive right to every improvement where the motive power is the electric or galvanic current, and the result is the marking or printing of intelligible characters, signs, or letters at a distance." (42) The Court held that the eighth claim was invalid, as it would inhibit the "onward march of science" and could be infringed even if a later invention did not fall within the patent's specifications. (43) While the Court found that the claims describing particular implementations of Morse's new technology were patentable, (44) the eighth claim removed the basic idea of communicating characters through electromagnetism from the common "storehouse" of ideas, encompassing a fundamental principle outside the reach of patent law's protections.

Although the exclusion of fundamental principles serves as a basic and well-established limit on patentable subject matter, the outer limits of this doctrine still remain unclear. (45) For example, some view the prohibited categories (laws of nature, physical phenomena, and abstract ideas) as reflecting a preference for applied research, while others see them as expressing other doctrines of patent law, such as novelty, as opposed to acting as independent limitations. (46) Despite this confusion, the exclusion of fundamental principles has spurred the adoption of several secondary rules, the most relevant here being the "mental steps" doctrine. (47)


The mental steps doctrine was initially developed by courts in the 1940s, and, as its name implies, served to exclude mental steps from patentable subject matter. (48) It was grounded in the "principle that a scientific concept or mere idea cannot be the subject of a valid patent." (49) Mental steps may be seen as falling within two of Chakrabarty's prohibited categories: human thought is an "abstract idea," and "the physiological processes involving neurons, neural networks, and electrical and neurochemical signals by which thoughts are generated within the brain are 'physical phenomena." (50) Courts applied the doctrine usually to inventions of mathematical formulae or computation methods; courts also applied the doctrine to claims in which a mathematical computation or mental operation was the sole novel element. (51) However, judicial decisions under the doctrine were inconsistent, as the definition of what constituted a mental step varied from case to case. (52)

In the 1970s, courts began rejecting the mental steps doctrine, (53) and today it is widely viewed as defunct. (54) The Supreme Court has never directly addressed the mental steps doctrine, although it has listed mental processes as unpatentable in Gottschalk v. Benson: "Phenomena of nature, though just discovered, mental processes, and abstract intellectual concepts are not patentable, as they are the basic tools of scientific and technological work." (55) While it is clear that patents may not be issued that entirely depend on mental processes, (56) mental steps have been accepted as components of patents with increasing frequency. For example, the USPTO has rejected the mental steps doctrine. (57) Also, the Federal Circuit now holds that the presence of a mental step in a patent is not determinative of patentability. (58)


As the mental steps doctrine declined, the Supreme Court developed another standard for patentable subject matter in 1972 known as the "machine or apparatus" test. (59) In Gottschalk v. Benson, the Court held that a mathematical formula that converted binary-coded decimal numerals into pure binary numerals was not patentable, as it had no substantial practical application except in connection with a digital computer. (60) The Court stated that a process is patentable if (1) it is "tied to a particular machine or apparatus" (61) or (2) it brings about a "[t]ransformation and reduction of an article 'to a different state or thing. …

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