Prometheus fails to steal fire from the Gods

Author: Jonathan Moss (Hogarth Chambers)

Mayo Collaborative Services v Prometheus Laboratories (US Supreme Court), 566 U.S. __ (2012), 20 March 2012

Journal of Intellectual Property Law & Practice (2012) doi: 10.1093/jiplp/jps086, first published online: June 15, 2012

The US Supreme Court has held that a medical process involving the determination of metabolite levels in relation to the toxicity or efficacy of a drug is unpatentable on the grounds that it amounts to patenting a law of nature.

Legal context

Under section 101 of the US Patent Act, ‘whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent’. This positive definition of what constitutes patentable subject matter differs from the position in Europe, where art 52 of the EPC defines patentability in the negative.

Nevertheless, the US Supreme Court has previously decided that ‘laws of nature, natural phenomena, and abstract ideas’ are non-patentable subject matter under s 101. To move an invention from being classed as a law of nature into patent-eligible subject matter, the patent must limit its reach to a particular inventive application of the law. The US Supreme Court visited this dividing line in this case in relation to medical diagnostics.


Prometheus is the sole and exclusive licensee of the two patents at issue. These patents cover the use of thiopurine drugs to treat certain autoimmune diseases. The problem to which the patent is addressed is that different people metabolize thiopurine to different extents. Thus, depending on this rate of metabolization, the provision of further doses to a patient may have an effect ranging from being too low and therefore having no medical effect, to too high which can be toxic.

The patents claimed a set of processes by which a doctor (1) administered the drug, (2) determined the metabolite levels in the blood, and (3) a ‘wherein’ step which described the likely effects of a dose and respectively indicated a need to increase or decrease the dosage.

The District Court at first instance held that the patent was invalid on the grounds that the processes claimed were natural laws or phenomena, ie the correlations between thiopurine metabolite levels and the toxicity/efficacy of thiopurine drugs. The Court of Appeals for the Federal Circuit (CAFC) reversed this decision, essentially on the grounds that, by limiting the application to use in and on the human body, the patent claims were confined to definite bounds and thus in compliance with section 101.

The CAFC based this decision on the ‘machine or transformation test’. The Supreme Court had recently held in Bilski that the ‘machine or transformation test’ was not a definitive test for patent eligibility and after Bilski had remanded the Prometheus case for reconsideration. The CAFC reaffirmed its earlier decision.


The decision of the Supreme Court was unanimous (9–0), with the opinion of the court being written by Justice Breyer. The court regarded the key question as being ‘whether the claims do significantly more than simply describe these natural relations’.

Having held that the relationship between thiopurine metabolite levels and the likelihood that it either causes harm or is medically beneficial was merely a natural phenomenon or law, the court proceeded to find that the additional features did not stop the claims from monopolizing a law of nature. The court viewed the discovery of this metabolic relationship as akin to Newton's laws of gravity or E = mc2.

The court stated that ‘the steps in the claimed processes (apart from the natural laws themselves) involve well-understood, routine, conventional activity engaged in by researchers in the field’. While this conclusion is not controversial, it appears that, in coming to its conclusion under s 101, the court factored in questions of obviousness and novelty. Such questions are arguably not relevant under s 101 because they are addressed by other provisions of the Patent Act (eg, s 103 deals with obviousness). Even though the court made heavy reference to its previously decided case law, the court did not rely on legal analysis alone. A facet of US Supreme Court jurisprudence is that the court often makes recourse to wider policy issues, and in this case the court relied on the underlying justification for the granting of patent monopolies. The court recognized that rewarding those who discover ‘new’ laws of nature might encourage people to discover them in the first place. However, the court also recognized the flip side of this, which is that scientific laws and principles are the ‘basic tools’ of scientific research, meaning that future research might be inhibited if a patent is granted.

Practical significance

The case has caused a stir among certain parts of the medical research and patent communities on the ground that it appears that diagnostic medicine treatments are now going to be inherently difficult to patent. Indeed, by comparing medical drug relationships (which differ from person to person) to overarching laws of science (such as the laws of gravity which have the same effect on everybody), the court has failed to make clear where exactly the line between law of nature and medical scientific advancement is to be drawn. This leads to considerable uncertainty over similar medical advancements as, in the medical field, a new ‘discovery’ is often the very thing that ends up being embodied in a patent and subsequently put in a drug. Questions therefore arise as to what extent this area of the medical market is now going to be protected by patent law. Significantly, this case may finally preclude any chance of patenting DNA or gene sequences.

While the court could arguably be criticized for bringing in questions of obviousness to patent eligibility, this criticism can be counterbalanced by the court considering the larger picture of scientific advancement in the field being potentially inhibited. This broader consideration of the impact of the decision is to be welcomed, as it is often a factor that can get overlooked when a strict statute and case law analysis is followed. Whether they got the answer to this question of inhibition in the relevant field correct is another matter.

As an increasing number of patent cases have reached the US Supreme Court in recent years, these decisions, along with the recent US patent legislation, mean that US patent law is undergoing a significant shift. Following this decision it appears that the US will no longer be as permissive in the granting of patents as it once was. As the US is arguably the world's leading centre for scientific innovation, changes in policy in the US will certainly have an impact on companies all around the world.

Another issue arising out of this case, which is relevant for European patent lawyers and attorneys, is the difference of opinion between the CAFC and the Supreme Court. The CAFC has special jurisdiction to hear patent cases in the US, and a number of the judges on it are specialist patent judges. This has led some commentators to complain that, because of their lack of relevant experience, the Supreme Court should defer more often to those courts with specialist patent backgrounds. Such a call will almost certainly be ignored, but it does demonstrate the tensions that can arise if the European system moves towards allowing the Court of Justice of the European Union to hear patent cases.

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