The US patent laws say that one may obtain a patent for a new and useful process, machine, manufacture, or composition of matter. But "laws of nature, natural phenomena, and abstract ideas" are not patentable, according to the US Supreme Court in Mayo v. Prometheus. At first glance, that seems to make sense, but on further reflection, it may not in the context of medical diagnostic methods.

In Mayo, the patent covered a process that enabled doctors who use a particular drug to treat patients with an autoimmune disease to determine whether a dosage was too low or high. The patent claimed: A method of optimizing therapeutic efficacy for treatment of an immune-mediated gastrointestinal disorder, comprising:

  1. administering a drug providing 6-thioguanine to a subject having said immune-mediated gastrointestinal disorder; and
  2. 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."

The Mayo court observed that "all inventions at some level embody, use, reflect, rest upon, or apply laws of nature, natural phenomena, or abstract ideas." However, the Court also observed that "to transform an unpatentable law of nature into a patent-eligible application of such a law, one must do more than simply state the law of nature while adding the words apply it.'" More specifically, according to the Court, "[p]urely conventional or obvious' [pre]solution activity' is normally not sufficient to transform an unpatentable law of nature into a patent eligible application of such a law. . . . And, "the prohibition against patenting abstract ideas 'cannot be circumvented by' . . . adding 'insignificant post-solution activity.'"

The Court viewed the Mayo patent claims as ones where they "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." With that interpretation of the claims, it would be difficult to argue that the patent was not valid.

Nevertheless, "friends of the court" filed briefs that argued that denying patent coverage here would impede future discoveries in diagnostic research. Others argued a contrary position, stating that allowing patent coverage would impede the use of scientific data. Whether either of the above arguments is valid, the Supreme Court did give hints as to what might make a diagnostic patent valid. The Court referred to a prior decision that found a patent valid and which related to a method of molding raw rubber. The method used a known mathematical equation to "determine when (depending upon the temperature inside the mold, the time the rubber had been in the mold, and the thickness of the rubber) to open the press." The patented steps included: "(1) continuously monitoring the temperature on the inside of the mold, (2) feeding the resulting numbers into a computer, which would use the [known] 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." According to the Mayo court, the patent was valid because "of the way the additional steps of the process integrated the equation into the process as a whole."

What the above example provides are hints to a prospective patent applicant of a diagnostic method of what needs to be present for patent validity. Of course, all patent applicants want a broad patent. But broad may be one thing and overly broad may be another. The Mayo patent may have just been overly broad, but with some "additional steps" the patent might have been saved.

For prospective patent applicants with a diagnostic method, bumping up against the prohibition of patenting a law of nature seems likely. But don't be greedy — provide some "additional steps" to your laws of nature so that the patent examiner has something to hang his/her hat on in order to grant your patent.

© Michael A. Shimokaji 2013

The contents of this article represent the opinions of the author and not those of the author's law firm or clients.

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