By: Audrey A. Millemann


The Supreme Court, in a very thoroughly written decision, Mayo Collaborative Services v. Prometheus Laboratories, Inc., 132 S. Ct. 1289 (March 20, 2012), has reiterated that laws of nature are not patentable.


The patent laws define patentable subject matter as “any new and useful process, machine, manufacture, or composition of matter.”  35 U.S.C. §101.  In a long line of cases going back to the mid-1800s, however, the Supreme Court has upheld an exception to patentable subject matter for “laws of nature, natural phenomena, and abstract ideas.”  Thus, while pretty much anything is patent-eligible, laws of nature (along with mental processes and abstract ideas) are not.


As the Supreme Court explained in Prometheus, there is a tension between these two positions.  On the one hand, granting patents that cover laws of nature, mental processes, or abstract ideas is likely to inhibit innovation by limiting the tools used in scientific research.  On the other hand, if this exception is strictly interpreted, no patent could be granted because all inventions are based in some way on a law of nature or abstract idea.  Thus, a new application of a law of nature might be patent-eligible, but it must also be more than the application of the law to a specific technology.


In Prometheus, the plaintiff was the exclusive licensee of two patents.  The patents claimed a method of “optimizing therapeutic efficacy” for treating certain autoimmune gastrointestinal diseases.  In the prior art, compounds known as thiopurines were used to treat these types of diseases.  The prior art recognized that thiopurines are metabolized differently by different patients and that the presence of specific metabolites in the blood- stream was correlated with the probability that the dose of thiopurine would be too high and cause harm or too low to be effective.


The inventors discovered the particular levels of the metabolites that were linked to the harm or ineffectiveness of thiopurines.  The patents claimed a method which required administering the thiopurine to provide the metabolite and determining the level of the metabolite in the blood stream.  The claims did not require that the person performing the method (the treating physician) actually increase or decrease the dose of thiopurine. 


Prometheus sold a diagnostic test kit used in performing the claimed method.  The defendant Mayo purchased and used the kits until 2004, when it decided to make and sell its own test kit. 


Prometheus sued Mayo for patent infringement.  The district court held that Mayo’s test kits infringed Prometheus’ patent, but granted summary judgment for Mayo on the grounds that the subject matter of the patent’s claims was a natural law or phenomenon.  The court held that the correlation between the metabolite levels and the harm or ineffectiveness of the thiopurine was a natural phenomenon, and that, therefore, the patent was invalid. 


Two trips through the Federal Circuit Court of Appeals and two trips to the Supreme Court led to the decision by the Supreme Court on March 20, 2012. 


The Supreme Court agreed with the district court that the correlations claimed by the patents were laws of nature.  The Court found that the correlations exist regardless of human action; they are a result of how the human body metabolizes thiopurines, and are, as such, a natural process.  Id.  at 1297. 


The Court explained that laws of nature are not patentable, nor are processes that describe such laws unless the process has “additional features.”  The Court stated, at 1297:


“[The process must have] additional features that provide practical assurance that the process is more than a drafting effort designed to monopolize the law of nature itself.  A patent, for example, could not simply recite a law of nature and then add the instruction ‘apply the law.’  Einstein, we assume, could not have patented his famous law by claiming a process consisting of simply telling linear accelerator operators to refer to the law to determine how much energy an amount of mass has produced (or vice versa).”


The Court analyzed the steps of the claims and found them to be nothing more than what the prior art had described.  The Court stated, at 1298:


“To put the matter more succinctly, 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…”


The Court reviewed its precedents in detail, emphasizing that its decision in Prometheus was consistent with those cases.  In Diamond v. Diehr, 450 U.S. 175 (1981), the Court had held that a process for molding uncured rubber was patentable, even though it used a mathematical equation, because the process included the additional steps of monitoring the temperature and triggering a mold to open at a certain time.  These steps were not conventional, known, or previously in use.  In Parker v. Flook, 437 U.S. 584 (1978), the Court had held that a process for adjusting “alarm limits” in the catalytic conversion of hydrocarbons was unpatentable because the process used a mathematical formula and did not have any steps limiting the claim to a specific application.  In comparison, the Court found that Prometheus’ argument for the patentability of its claims was not as strong as that in Diamond v. Diehr and was as weak as that in Parker v. Flook. 


The Court also addressed its concern that “patent law not inhibit further discovery by improperly tying up the future use of laws of nature.”  Id. at 1301The Court cautioned that the grant of patents for applications of laws of nature might well hinder future innovation.  Id. at 1301.  This is especially true if the claimed process is really just an instruction to apply the law of nature. Id.  The risk, the Court explained, is that such a patent would cover far more than what the inventor invented and would preclude innovation in areas which are not justified.  Id. at 1301-02.  Even though the law of nature in Prometheus’ claims was a narrow one, the Court held that the claims would foreclose too much of the field in the future. 


The Court considered and dismissed several arguments made by Prometheus and others.  First, the Federal Circuit had found the claims patentable based on the machine or transformation test, finding that the human body and the blood were transformed by the process.  The Court held that the machine or transformation test did not “trump the law of nature exclusion.” Id.  at 1303. 


Second, the Government argued that a process should be patentable if it includes any step applying a law of nature, and that the requirements of novelty and nonobviousness would be sufficient to determine patentability.  The Court held that the case law establishing the exception to patentable subject matter under §101 for laws of nature was binding precedent, and that the question of patentable subject matter was and should be a separate issue from the requirements of novelty and nonobviousness. Id.  at 1303-04.


Lastly, the Court agreed with many amici, including the American Medical Association and other medical groups, that finding Prometheus’ claims patentable would inhibit the ability of physicians and medical researchers to provide the best care to patients and to advance their field.   Id. at 1304.