October 17, 2019

October 17, 2019

Subscribe to Latest Legal News and Analysis

October 16, 2019

Subscribe to Latest Legal News and Analysis

October 15, 2019

Subscribe to Latest Legal News and Analysis

Supreme Court Rules in Prometheus: Patent Claims Must Recite “Significantly More” than a Law of Nature

In a move that could have a significant impact on the fields of personalized medicine and medical diagnostics, the Supreme Court of the United States recently held claims to a blood test were invalid because they did not define patent-eligible subject matter.

Speaking through Justice Breyer, a unanimous Supreme Court of the United States has brought the closely watched Mayo Collaborative Services v. Prometheus Laboratories, Inc., Case No. 1150 (Supreme Court March 20, 2012), to a close, reversing the U.S. Court of Appeals for the Federal Circuit and holding that the claims directed to a blood-testing method are invalid because they do not define patent-eligible subject matter.  Starting from the venerable premise that laws of nature, natural phenomenon and abstract ideas are not patentable, the Supreme Court explained that in order to transform an unpatentable law of nature into a patent-eligible method, the claims must do more than simply recite the law of nature while adding the words “apply it.”  Rather, the scope of the claims must be limited by a “particular inventive application of the [natural] law.”  In this instance, the Supreme Court concluded the claims embody natural relations, but fail to do “significantly more than simply describe … [the] natural relations,” and do not “add enough to their statements of the correlations to allow the processes they describe to qualify as patent-eligible processes that apply natural laws” (emphasis in original). 

This decision may have substantial implications for the fields of personalized medicine and medical diagnostics, potentially affecting their business models


Prometheus sells diagnostic tests covered by two patents and, for a time, Mayo purchased these tests from Prometheus.  In 2004, however, Mayo began to use and sell its own version of the test.  The district court found Mayo’s test to infringe, but ultimately found the patents to be invalid on the grounds that it was drawn to subject matter ineligible for patenting under 35 USC § 101. 

On appeal, the Federal Circuit reversed the District Court’s holding, finding that the claims were patentable because they recited steps that met the Federal Circuit’s “machine or transformation” test.  Mayo appealed to the Supreme Court, which granted cert but then vacated the Federal Circuit’s holding and remanded the case for reconsideration in light of its then recent holding in In re Bilski.  In Bilski, the Supreme Court held that the “machine or transformation” test was not the definitive test for patentable subject matter, but merely an informative tool for determining the patentability of subject matter within the context of a more holistic approach. 

On remand, the Federal Circuit again found the claims to recite patentable subject matter.  Mayo appealed (for a second time) to the Supreme Court.

Claims Must Recite “Significantly More” than a Law of Nature

The claims recite methods physicians may use to determine if a patient’s administered dose of a thiopurine drug is too low and thus ineffective, or too high and thus potentially toxic.  Because different patients metabolize drugs differently, it is not always easy for a physician to initially prescribe the correct dose.  Claim 1 of the Mayo patent is exemplary and states:

  1. A method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder, comprising:
    (a)  administering a drug providing 6-thioguanine to a subject having said immune-mediated gastrointestinal disorder; and
    (b)  determining the level of 6-thioguanine in said subject having said immune-mediated gastrointestinal disorder,
                            wherein the level of 6-thioguanine less than about 230 pmol per 8x108 red blood cells indicates a need to increase the amount of said drug subsequently administered to said subject and
                            wherein the level of 6-thioguanine greater than about 400 pmol per 8x108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.

As viewed by the Supreme Court, this claim essentially recites a two-step method.  An “administering” step, in which a drug is administered in any possible way, and a “determining” step, in which levels of a metabolite of the drug are measured, again in any possible way.  The claim concludes with “wherein” clauses that do not recite an actual step of modifying the dosage level, but merely specify observation of certain metabolite levels “indicates a need” to either increase or decrease the dosage of the drug during the administering step.  In other words, the claims do not require dose modification to occur, but merely describe what a treating physician might learn from observing the metabolite levels.

The Supreme Court concluded the claims do not sufficiently transform a natural law, i.e., the correlation between a metabolite level and the need to increase or decrease drug dose, into a patent-eligible application of the law because “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.”  As Justice Breyer explained, “If a law of nature is not patentable, then neither is a process reciting a law of nature, 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.”

The Supreme Court analyzed whether the claims include the requisite “additional features” by examining each part of the claim individually and the claim as a whole.  The court found the steps of the claim “simply tell doctors to gather data from which they may draw an inference in light of the correlations,” and ultimately concluded “the steps are not sufficient to transform unpatentable natural correlations into patentable applications … .”

In particular, the Supreme Court found “the ‘administering’ step simply refers to the relevant audience, namely doctors who treat patients with certain diseases with thiopurine drugs.”  In the court’s view, this step fails to add anything beyond a mere application of the law of nature because the step is not novel or inventive, as doctors have “used thiopurine drugs to treat patients suffering from autoimmune disorders long before anyone asserted these claims.”

Similarly, the Supreme Court found the “determining” step involves “methods for determining metabolite levels [that were] well known in the art,” and so “this step tells doctors to engage in well-understood, routine, conventional activity previously engaged in by scientists who work in the field.”  The court also concluded “the ‘wherein’ clauses simply tell a doctor about the relevant natural laws, at most adding a suggestion that he should take those laws into account when treating his patient.”

Finally, even when considered as a whole, the Supreme Court found the claims failed to constitute patentable subject matter.  Justice Breyer explained, “the claims inform a relevant audience about certain laws of nature; any additional steps consist of well-understood, routine, conventional activity already engaged in by the scientific community; and those steps, when viewed as a whole, add nothing significant beyond the sum of their parts taken separately.”

In sum, the Supreme Court explained that, when a patent claim involves reliance on a natural law or correlation, the claim must contain “significantly more” than that natural law alone.  Prometheus’ claims fail in this regard because the claimed method steps “add nothing specific to the laws of nature other than what is well-understood, routine, conventional activity, previously engaged in by those in the field.”  The court concluded that the claims simply “tell doctors to apply the law somehow when treating their patients.”

Patent Claims Cannot Monopolize Laws of Nature

A theme running through Justice Breyer’s opinion is the policy concern that the “patent law not inhibit further discovery by improperly tying up the future use of laws of nature.”  The Supreme Court acknowledged that, on one hand, discovery of new natural laws is important and should be encouraged.  On the other hand, however, “those laws and principles, considered generally, are ‘the basic tools of scientific and technological work,’” and denying the scientific community access to those tools will stifle future innovation (quoting Gottschalk v. Benson, 409 U. S. 63 (1972)). 

The Supreme Court reviewed several amici curiae on both sides of the issue, and ultimately concluded “the underlying functional concern here is a relative one: how much future innovation is foreclosed relative to the contribution of the inventor.”  In Prometheus, the Supreme Court found the claims tip the balance too far in the direction of stifling innovation by tying “up the doctor’s subsequent treatment decision whether that treatment does, or does not, change in light of the inference he has drawn using the correlations.”

The Future of Diagnostic Claims

Notably, however, the Supreme Court did not completely shut the door on all claims involving laws of nature.  It confirmed that claims to novel compositions or methods of treatment will still constitute patentable subject matter, even if they involve laws of nature.  Indeed, the court contrasted two prior Supreme Court cases relating to the patentability of claims involving laws of nature, Diamond v. Diehr, 450 U.S. 175 (1981) (upholding claims involving natural laws) and Parker v. Flook, 437 U.S. 854 (1978) (invalidating claims involving natural laws).  The Supreme Court likened Prometheus to Flook, stating the claims in both cases simply recited laws of nature and instructions to apply those laws in known, conventional ways.

The Supreme Court in Diehr, however, found the law of nature in the claims did not stand alone, but that there were additional elements that transformed the claim into a patentable application of the law of nature.  Notably, the Prometheus Supreme Court commented nothing suggested that these additional elements, or at least the combination of the additional elements, “were in context, obvious, already in use, or purely conventional.”

The Supreme Court did not address whether the Prometheus claims might be patent eligible if the administering, and determining steps were less conventional.  However, the opinion suggests that inclusion of novel and inventive additional features in the Prometheus claims might have transformed them into a patentable application of the natural law.

35 USC § 101 Should Not Be Conflated with Other Patentability Provisions

In its amicus brief, the U.S. Government argued that almost any step beyond a simple recitation of the law of nature should suffice to meet the § 101 standard, and that other sections of the code (e.g., 35 USC §§ 102, 103 and 112) are sufficient to screen claims for patentability.  The Supreme Court rejected this argument, noting that such an approach “would make the ‘law of nature’ exception to 35 USC §101 patentability a dead letter.” 

While acknowledging that sometimes the §§ 101 and 102 inquiries “sometimes overlap,” the Supreme Court concludes the inquiries are different, “[a]nd to shift the patent eligibility inquiry entirely to these later sections risks creating significantly greater legal uncertainty, while assuming that those sections can do work that they are not equipped to do.”

The Supreme Court expressly declined the invitation of the U.S. Government to simply discount or ignore a law of nature, to the extent it is recited in a claim, when evaluating novelty (§ 102) or obviousness (§ 103) as a whole, or when evaluating compliance with § 112, noting that such an approach would “not [be] consistent with prior law;” citing to Bilski, Diehr, Flook and Benson.

Practice Notes

Prometheus may have a significant effect on the fields of personalized medicine and medical diagnostics.  While Prometheus does not create a blanket rule that claims that rely upon natural correlations or other laws of nature are not patentable, it does provide guidance that is useful for determining whether claims might fail under § 101.  Patent owners and licensees may wish to review and analyze their claims in view of Prometheus, and might consider taking actions (e.g., through reexamination or reissues) to address any perceived weaknesses.

Prometheus shows there are no absolute bright line rules for determining patent-eligible subject matter under § 101.  While the precise claim language is important for determining whether claims are patent eligible, the Supreme Court expressed concern with too-clever practitioners trying to draft around the § 101 requirement, stating that patent eligibility should not “depend simply on the draftsman’s art.”  Thus, the particular law of nature, the method steps in applying the law of nature, and the scope and field of the claim are all relevant factors that should be considered when determining whether claims define patent eligible subject matter.  At a minimum, claims drafters should parse out the law of nature in the claim from the other claim language, and ensure the other claim language constitutes substantial additional features that go beyond a mere instruction to apply the law of nature.  What is not absolutely clear from the Prometheus decision is what type of language will or will not suffice to meet this standard. 

© 2019 McDermott Will & Emery


About this Author

K. Nicole Clouse, McDermott Will Emery law Firm, Intellectual Property Attorney

K. Nicole Clouse, Ph.D., is an associate in the law firm of McDermott Will & Emery LLP and is based in the Firm’s Boston office.  She focuses her practice on patent preparation, prosecution and portfolio management in the life sciences industry.  Nicole also assists with the preparation of patentability, freedom to operate, validity and infringement opinions and advises litigation teams on technical scientific matters.  She has worked with a wide variety of clients, including...

William Gaede, Life Sciences Attorney, McDermott Law Firm

William (Bill) Gaede is a partner in the law firm of McDermott Will & Emery LLP and is based in the Firm’s Silicon Valley office. Bill co-chairs the Firm’s Life Sciences & Medical Devices group and is a member of the Firm’s Personalized Medicine Team. He also serves as hiring partner for the Silicon Valley office.