Section 101 of the Patent Act defines patentable subject matter. The statute says the following:

“Whoever invents or discovers any new and useful process, machine, manufacture, or composition or matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.” 35 U.S.C. 101

In a recently handed down decision  ”Mayo v. Prometheus Laboratories” the US Supreme Court has again taken center stage and emphasized  its view that “laws of nature” and “basic tools of scientific and technological work” are not covered by the above statute and thus are not subject to protection as a patent.

The patent at issue in Prometheus related to the use of “thiopurine” drugs in the treatment of autoimmune diseases such as Crohn’s disease. When a patient ingests the drug, the body metabolizes it in the bloodstream. Because different people metabolize the drug differently, the same dose of the drug affects different people differently, and it has been difficult for doctors to determine whether a particular dose is too low and thus ineffective or too high risking harmful side effects. The patents to Prometheus (US Patent No: 6,355,623 and US Patent No. 6,680,302) covered findings that concentrations in the patient’s blood of the metabolite beyond a certain level indicated that the dosage is too high. The claim at issue was the following:

“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 8×108 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 8×108 red blood cells indicates a need to decrease the amount of said drug subsequently administered to said subject.”

The US Supreme Court held that the patent set forth laws of nature – namely, relationships between concentrations of certain metabolites in the blood and the likelihood that dosage of a thiopruine drug will prove ineffective or cause harm. The relationship according to the court is a consequence of the ways in which thiopruine compounds are metabolized by the body -entirely natural processes. According to the court, the “wherein” clause simply tells a doctor about the relevant natural laws, at most adding a suggestion that he should take those laws into account when treating his patient much like Einstein telling linear accelerator operators about his basic law and then trusting them to use it where relevant. In addition, the other steps were already well known in the art (i.e., administering the drug and determining metabolites in the blood). The court stated that the claim is much like a prior claimed process (Flook) held unpatentable which provided a method for adjusting “alarm limits” in the catalytic conversion of hydrocarbons.

In Flook, certain operating conditions (such as temperature, pressure, and flow rates), which are continuously monitored during the conversion process, signal inefficiency or danger when they exceed certain “alarm limits”. The claimed process amounted to an improved system for updating those alarm limits through the steps of (1) measuring the current level of the variable (e.g., the temperature) using an apparently novel mathematical algorithm to calculate the current alarm limits and (3) adjusting the system to reflect the new alarm-limit values”) The Court pointed out that the basic mathematical equation, like a law of nature, was not patentable, and it characterized the claimed process as doing nothing other than “providing a unpatentable formula for computing an updated alarm limit”. The Supreme Court analigized the Prometheus claims to Flook by stating that the claims at issue present a case for patentability that is no stronger than Flook. “Beyond picking out the relevant audience, namely those who adminsiter doses of thiopurine drugs, the claim simply tells doctors to: (1) measure the current level of the relevant metabolite, (2) use particular (unpatentable) law of nature to calculate the current toxicity/inefficacy limts and (3) reconsider the drug dosage in light of the law.” According to the Court, “these instructions 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. And since they are steps that must be taken in order to apply the laws in question, the effect is simply to tell doctors to apply the  law somehow when treating their patients”.

A possible criticism of the Court’s opinion is the question “What is not a law of nature?”  Is not everything that occurs in the real world a law of nature? Clearly, knowing a lower limit where a drug is ineffective and thus dosage should be increased and an upper limit where dosage to be increased is something that doctors might want to know and will not discover on their own. Without patents to protect the disccovery of such a relationship, will future inventors have any incentive to discover such relationships?

For purposes of the inventor, the more relevant question is how should process patents be written in the future in order to avoid the patent being held invalid as not covering patentable subject matter?  Unfortunately, the Supreme Court decision does not leave much guidance in this respect.

The Supreme Court does give some hints as to what may be patentable by pointing to cases where such process patents were held to be patentable. For example, the Court point to a prior decision (Dierh) where a process used a known mathematical equation (the Arrhenius equation) to determine when (depending upon the temperature inside a mold, the time the rubber had been in the mold, and the thickness of the rubber) to open a press. That patent claim consisted of the steps of : (1) continuously  monitering the temperature on the inside of the mold (2) feeding the resulting numbers into a computer, which would use the Arrhenius equation to continuously recalculate the mold-opening time , and (3) configuring the computer so that at the appropriate moment it would signal a device to open the press.”

While the Court in Diehr held that the basic mathematical equation, like a law of nature, was not patentable, it found the overall process patent eligible because of the way the additional steps of the process integrated the equation into the process as a whole. Those steps included “installing rubber in a press, closing the mold, constantly determining the temperature of the mold, constantly recalculating the appropriate cure time through the use of the formula and a digital computer, and automatically opening the press at the proper time” Importantly, the court noted importantly that in Dierh, the Court nowhere suggested that all these steps, or at least the combination of those steps, were in context obvious, already in use, or purely conventional unlike the steps in Prometheus. The Court further noted that patentees did not seek to pre-empt the use of the equation, but sought only to foreclose from others the use of that equation in conjunction with all of the other steps in their claimed process. These other steps apparently added to the formula something that in terms of patent law’s objective had significance – they transformed the process into an inventive application of the formula. This last point — tying up a field (i.e., tying up a doctor’s subsequent treatment decision whether that treatment does, or does not, change in light of the inference he has drawn using the correlations in the patent) seemed to be what bothered the Court the most as to the claims. The Court stated that they threaten to inhibit the development of more refined treatment recommendations that combine these correlations with later discovered features of metabolites, human physiology or individual patient characteristics.

In conclusion, steps like “determining” which set forth broad language covering conventional or known processes which may preempt future scientific discovery relating to such processes is probably something to try to avoid when drafting process claims. Other than this, each case must be decided based on its own facts, and the likelihood of mixed ad hoc application by the courts to these facts are likely to increase as a result of the decision by the Supreme Court.