Today the U.S. Supreme Court issued its much-awaited decision in Mayo Collaborative Services v. Prometheus Laboratories, Inc. The Court unanimously held that claims on methods of determining whether drug dosing levels should be increased or decreased based on levels of a metabolite in a patient’s bloodstream were not patent-eligible. According to the Court, the claims sought to monopolize a law of nature and their inclusion of additional steps reciting “well-understood, routine, conventional activity previously engaged in by researchers in the field” did not render them patentable. In the Court’s view, “upholding the patents would risk disproportionately tying up the use of the underlying natural laws, inhibiting their use in the making of further discoveries.” The Court’s decision may have wide-ranging implications for the validity and scope of method patents in a variety of fields, including software, business methods, health care and biotechnology.

The Supreme Court’s Historical Difficulty Defining the Scope of Patent-Eligible Subject Matter Under Section 101 of the Patent Act

Section 101 of the Patent Act of 1952, 35 U.S.C. § 101, directs the U.S. Patent and Trademark Office (PTO) to issue patents to “[w]hoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof.” The Supreme Court has long recognized an implicit exception, however: laws of nature, natural phenomena and abstract ideas are not patentable.

For example, in O’Reilly v. Morse, 56 U.S. 62 (1854), the Court rejected as unpatentable Samuel Morse’s claim to “the use of the motive power of the electric or galvanic current … for making or printing intelligible characters, letters, or signs, at any distances.” The Court expressed concern that “some future inventor … may discover a mode of writing or printing at a distance by means of the electric or galvanic current, without using any part of the process or combination set forth in the plaintiff’s specification. … But yet if it is covered by this patent the inventor could not use it, nor the public have the benefit of it without the permission of this patentee.”

In the last 40 years, the Supreme Court has taken an increasing interest in patent-eligibility issues due to the increase in patent applications covering software, business methods and biotechnology. In Gottschalk v. Benson, 409 U.S. 63 (1972), the Court addressed the patentability of a software process using a mathematical algorithm to convert binary numbers from one encoding scheme to another. Although such a conversion could be used in a variety of practical computer applications, the claims were not limited to any particular application. The claims did recite the use of a hardware element (a reentrant shift register), but the Court nevertheless held that the claims were directed to an abstract idea and therefore were not patentable. According to the Court, “[t]he mathematical formula involved here has no substantial practical application except in connection with a digital computer, which means that if [patentability] is affirmed, the patent would wholly pre-empt the mathematical formula and in practical effect would be a patent on the algorithm itself.”

The Court took up the issue again six years later in Parker v. Flook, 437 U.S. 584 (1978). The process claims there involved a practical software application of a mathematical formula (updating the value of an alarm limit for ending a chemical reaction), but the only novel feature of the process was the specific manner in which the alarm limit was calculated. The Court found the claims unpatentable, characterizing the issue as “whether the identification of a limited category of useful, though conventional, post-solution applications of such a formula makes respondent’s method eligible for patent protection.” The Court concluded that the claims were not patentable because the post-solution activity of updating an alarm limit for use in regulating a chemical reaction was not novel. The Court thus appeared to hold that the novel use of a piece of knowledge (there the formula embodied in the software) as part of a practical application did not render that use patentable. Rather, the practical application itself had to be novel.

The Court limited the reach of Flook three years later in Diamond v. Dehr, 450 U.S. 175 (1981). The claims in Diehr applied a known mathematical equation to software for controlling an automated rubber curing process. The calculation used in Diehr’s process of curing rubber had been well known in the art, but using a computer to perform the calculation ensured that an accurate, current value was always available. In finding the claims patentable, the Court reasoned that Benson and Flook merely restated long-settled doctrine that laws of nature, natural phenomena and abstract ideas are not statutory subject matter and had not created any new doctrine related to mathematical algorithms or software. The Court also criticized the Flook analysis, suggesting that it was inappropriate to dissect claims into old and new elements and then ignore the presence of the old elements in the analysis. In addition, the Court stated that the novelty of any element in a process has no bearing on whether the subject matter is within the scope of the patent laws. Although the Court reaffirmed that abstract mathematical formulas are not patentable, it also reiterated that claims incorporating a particular formula can be patentable if they are directed to a practical application: “when a claim containing a mathematical formula implements or applies that formula in a structure or process which, when considered as a whole, is performing a function which the patent laws were designed to protect (e.g., transforming or reducing an article to a different state or thing), then the claim satisfies the requirements of § 101.”

The Gottschalk-Flook-Diehr trilogy left the law in disarray. Nevertheless, for the next 19 years the Court declined to take any cases involving patentable subject matter. In 2006, the Court appeared ready to take on the issue when it granted certiorari in Laboratory Corporation of America Holdings v. Metabolite Laboratories, which involved the patentability of a process of using a test to measure the level of the amino acid homocysteine in a body fluid and then determining, based the homocysteine level, whether a vitamin deficiency was likely. The Court dismissed the writ of certiorari as improvidently granted, however. Justice Breyer’s dissent, joined by two other justices, argued that the case was fit for review, that the public interest implications of Section 101 argued for “clarifying the law in this area sooner rather than later” and that LabCorp’s process was unpatentable because it was “no more than an instruction to read some numbers in light of medical knowledge.”

The Court finally revisited the matter in Bilski v. Kappos, 130 S. Ct. 3218 (2010), but its fractured, narrow opinion did little to clear up the law. In Bilski, an applicant sought a patent on a method for hedging the risk of providing a commodity by using a combination of fixed supply contracts and futures contracts determined by a set of mathematical techniques and formulas. Both the claims and the application as a whole failed to mention any particular machines used to perform the methods or any particular ways in which such machines could be programmed and used to perform them. After the PTO rejected the claims as lacking patent-eligible subject matter, Bilski appealed to the Federal Circuit.

In an en banc decision, the Federal Circuit distilled a “machine-or-transformation” test from the Supreme Court’s earlier decisions regarding Section 101. According to the majority, a method or process is eligible for patent protection only if “(1) it is tied to a particular machine or apparatus, or (2) it transforms a particular article into a different state or thing.” Applying that test, the Federal Circuit found Bilski’s claims unpatentable. The claims failed to recite performance by a particular machine, and the court held that data about financial transactions are neither physical objects or substances themselves nor “representative” of any physical object or substance.

The Supreme Court granted review and affirmed the rejection of the claims, but it declined to endorse the “machine-or-transformation” test. According to the majority, that test was “a useful and important clue, an investigative tool, for determining whether some claimed inventions are processes under § 101,” but it was “not the sole test for deciding whether an invention is a patent-eligible ‘process.’” The Court split as to the patentability of business method patents in general, with a 5-4 majority holding that some business methods may be patentable. But the Justices unanimously agreed that Bilski’s claims were unpatentable under Section 101 because he merely claimed the abstract concept of hedging risk in commodities markets in a particular mathematical way.

The Factual and Procedural Background of Prometheus

The patents at issue in Prometheus concerned the use of thiopurine drugs in the treatment of autoimmune diseases such as Crohn’s disease and ulcerative colitis. According to the patents, doctors faced a difficulty in determining whether a given dose of 6-mercaptopurine (6-MP) for a particular patient was too high (risking harmful side effects) or too low (and therefore ineffective). The patentees, who were two doctors from a hospital in Montreal, claimed to have invented a method for optimizing dosage of a thiopurine drug allowing a clinician to determine a clinically effective dosage without unnecessary risk of harm to the patient.

The claimed methods covered a diagnostic test based on the correlation between levels of particular metabolites of thiopurine compounds in the patient’s blood and the likelihood that treatment would either cause harm or be ineffective. Previous studies cited to the PTO during prosecution of the patents suggested that the measurement of 6-thioguanine (6-TG) and 6-methyl-mercaptopurine (6-MMP) in the patient’s blood could be used to predict clinical efficacy and tolerance for the administration of 6-MP, but those studies did not define the precise correlation between metabolite levels and likely harm or ineffectiveness. The two Canadian researchers identified those correlations with more precision and sought patent protection for their findings. The issued claims involved the steps of administering a thiopurine drug (such as 6-MP) to a patient, and determining the level of a metabolite (such as 6-TG or 6-MMP) in the patient, “wherein [a level of the metabolite below a certain level] indicates a need to increase the amount of said drug subsequently administered to said subject, and wherein [a level of the metabolite above a certain level] indicates a need to decrease the amount of said drug subsequently administered to said subject.”

Prometheus Laboratories, the exclusive licensee of the patents, sold diagnostic tests that embodied the patented claims. The Mayo Clinic initially purchased those tests from Prometheus, but then developed and used its own test, also based on a correlation between metabolite levels and toxicity. Prometheus then sued Mayo for patent infringement.

The district court found that Mayo’s test infringed, but held that the claims were unpatentable under Section 101. According to the district court, the claims effectively covered the correlation between metabolite levels and therapeutic efficacy or toxicity because the final “wherein” step was only a “mental step” and the correlations resulted from a natural body process.

On appeal, the Federal Circuit reversed. 581 F.3d 1336 (2009). Without the benefit of the Supreme Court’s decision in Bilski, the panel found that the steps of (1) administering a drug to a patient, and (2) determining the resulting metabolite level satisfied its “machine-or-transformation” test. The panel found that the “transformation” prong was satisfied both by the transformation of the patient’s body following the administration of thiopurine drugs and by various chemical and physical changes of the drugs’ metabolites that enable concentrations to be determined. The panel accepted Prometheus’s argument that the various methods of manipulating patient blood samples to determine the levels of metabolites present in the subject, such as the high-pressure liquid chromatography (HPLC) specified in some dependent claims, necessarily “transformed” the patient’s blood. The panel further reasoned that the “administering” and “determining” steps were more than “mere data-gathering” and thus rendered the claims patent-eligible.

Mayo then sought review by the Supreme Court, which granted certiorari, vacated, and remanded for reconsideration in light of the Supreme Court’s decision in Bilski that the machine-or-transformation test was not the sole test for determining the patent-eligibility of process claims. On remand, the Federal Circuit again held that Prometheus’s claims recited patentable subject matter under Section 101. 628 F.3d 1347 (2010). The panel noted that although the Supreme Court did not endorse the “machine-or-transformation” test as the sole test for patentability, the Court did not disavow that test either. The panel reaffirmed its earlier reasoning that the “transformations” of the thiopurine drugs and the patient’s blood rendered Prometheus’s claims patent-eligible. The panel also reaffirmed its view that the sequence of steps in Prometheus’s method claims would not preempt all use of the identified correlation between metabolite levels and toxicity or clinical efficacy.

The Supreme Court’s Decision

The Supreme Court again granted certiorari, and a unanimous Court has now reversed the Federal Circuit’s judgment and held that Prometheus’s claims were unpatentable under Section 101. Justice Breyer, who dissented in LabCorp, wrote for all nine Justices. The Court read its cases to warn “against interpreting patent statutes in ways that make patent eligibility ‘depend simply on the draftsman’s art’ without reference to the ‘principles underlying the prohibition against patents for [natural laws].’” The question, according to the Court, was whether Prometheus’s claims added “enough to their statements of the correlations to allow the processes they describe to qualify as patent-eligible processes that apply natural laws.” The Court held that they did not, reasoning that “the steps in the claimed processes (apart from the natural laws themselves) involve well-understood, routine, conventional activity previously engaged in by researchers in the field” and that “upholding the patents would risk disproportionately tying up the use of the underlying natural laws, inhibiting their use in the making of further discoveries.”

As a basic principle, the Court held that a process “reciting a law of nature” is not patent-eligible “unless that process has additional features that provide practical assurance that the process is more than a drafting effort designed to monopolize the law of nature itself.” In this case, the Court reasoned that the “administering” step of the claims simply referred to a preexisting audience: doctors who treat patients with certain diseases with thiopurine drugs. The “wherein” clauses, according to the Court, merely told doctors to take the relevant natural laws into account when treating patients. And the “determining” step just told doctors to determine levels of the relevant metabolites, which the Court deemed “well-understood, routine, conventional activity previously engaged by scientists who work in the field.” The Court reiterated its previous holdings that conventional or obvious pre- or post-solution activity cannot transform an unpatentable law of nature into a patentable application of such a law. The Court further concluded that taking the claimed steps as a whole added nothing significant to the sum of the parts taken separately.

The Court then focused on its precedents (primarily Diehr and Flook) and concluded that they supported the same result. The Court further expressed concern that “patent law not inhibit further discovery by improperly tying up the future use of laws of nature.” In its view, the claims “threaten[ed] to inhibit the development of more refined treatment recommendations (like that embodied in Mayo’s test), that combine Prometheus’ correlations with later discovered features of metabolites, human physiology or individual patient characteristics.”

The Court also dismissed the Federal Circuit’s reliance on the “machine-or-transformation” test. The first “transformation” (the chemical interaction between the patient’s body and the thiopurine drugs) merely defined the context in which Prometheus’ patented correlation applied, rather than the process itself. The Court reasoned that the second “transformation” (the physical manipulation involved in determining metabolite levels) could be satisfied without transforming the blood if an appropriate method were developed in the future. As in Bilski, the Court did not disavow the “machine-or-transformation” test, noting again that the test is an “important and useful clue” regarding patentability under Section 101, but it clarified that the test does not trump the “law of nature” exclusion.

The Court further held that it did not matter whether the law of nature claimed in a patent was a narrow principle or a broad one. The Court noted that its concern was “a relative one: how much future innovation is foreclosed relative to the contribution of the inventor.” Observing that “courts and judges are not institutionally well-suited to make the kinds of judgments necessary to distinguish among different laws of nature,” the Court reaffirmed the bright-line rule against patenting any law of nature.

The Court also addressed the overlap between Section 101 and the more frequently litigated validity provisions of the Patent Act, Sections 102 (anticipation), 103 (obviousness) and 112 (written description and enablement). The Court rejected the Solicitor General’s argument for the federal government that “virtually any step beyond a statement of a law of nature itself should transform an unpatentable law of nature into a potentially patentable application sufficient to satisfy § 101’s demands.” The government had argued that the application of Sections 102, 103 and 112 could address the Court’s concerns about overly broad patents preempting entire fields of discovery. In particular, the government argued that claims encompassing known scientific principles would be likely to fail under Section 102 for lack of novelty. But the Court disagreed, stating that the government’s proposal “would make the ‘law of nature’ exception to § 101 patentability a dead letter.” According to the Court, the government’s approach would create excessive uncertainty and would be either over- or underinclusive. A newly discovered law of nature might be novel and nonobvious but nevertheless clearly excluded by Section 101. Conversely, treating all laws of nature as prior art might “make all inventions unpatentable because all inventions can be reduced to their underlying principles of nature which, once known, make their implementation obvious.”

The Court briefly addressed the large number of amicus curiae briefs filed on behalf of both parties. Amici on behalf of Prometheus argued that limiting patents on diagnostic methods would interfere with diagnostic research. Amici on behalf of Mayo, such as the American Medical Association and a variety of health care providers, countered that allowing broad claims covering natural responses to illness and medical treatment would put off limits critical scientific data needed to provide sound medical care. Ultimately, the Court declined to wade into the debate, finding no reason to depart from what it viewed as established principles of patent law and noting that Congress may adopt more finely tailored rules if it desires.

The Court did not specifically address whether the more specific limits in some of the dependent claims, such as the use of HPLC to “determine” the concentration of thiopurine metabolites, were sufficient to satisfy Section 101. Nevertheless, the Court’s unqualified conclusion that “the patent claims at issue effectively claim the underlying laws of nature” and “are consequently invalid” indicates that those claims also have been rejected. The Court’s opinion also did not clarify whether narrower, more detailed claims might have survived. For example, it is unclear whether claims would have been upheld if they had been directed to a method of treating Crohn’s disease comprising administering a specific drug, determining metabolite levels (via HPLC or another specified means) and adjusting the dosage based on the metabolite levels.

The Future

The Court’s critical discussion of creative drafting efforts may suggest that it would not look favorably on efforts to distinguish Prometheus simply by adding steps. On the other hand, a patent owner could argue that the additional steps would make the claims a patentable application of a law of nature rather than an attempt to monopolize it, much like the method for determining the time to open a rubber press in Diehr. Moreover, narrower claims limited to a particular method for applying a known principle may satisfy the Court’s longstanding concerns about a patentee preempting a field of invention much larger than his or her own discovery.

At minimum, Prometheus is likely to make Section 101 an increasingly useful tool for an accused infringer to attack process patents—particularly those covering diagnostic methods. In addition, even if a process patent asserted in litigation is not invalidated under Prometheus, an accused infringer could invoke the Court’s preemption concerns to argue for a narrower claim scope closer to the embodiments disclosed by the patentee. Because the Court’s opinion leaves much to be clarified, the real impact of Prometheus will be seen in future PTO and Federal Circuit decisions. At its narrowest, the case could be read to affect particular, unusual claims that make the mistake of claiming a known, conventional step that only takes place in a doctor’s head. Read more broadly, Prometheus could call into question a wide range of method patents. Time will tell.

© 2012 Perkins Coie LLP