Diagnostic Methods as a Category of Patent-Ineligible Subject Matter

By: Angeline Premraj


The authority to grant to patents arises from Article Eight of the United States Constitution. Specifically, Clause Eight grants Congress the power to “promote the Progress of Science and useful Arts, by securing for limited Times to Authors and inventors the exclusive right to their respective Writings and Discoveries.” Through this clause, Congress is empowered by the Constitution to grant copyrights and patents. Under this authority, Congress has enacted and promulgated various statutes in furtherance of promoting the progress of science and the useful arts. One such statute is 35 U.S.C. § 101, whose interpretation has been embroiled in controversy over the past decade. The statute delineates the types of subject matter that are patentable. Section 101 renders patentable “any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof.”

Laws of nature and natural phenomena are prima facie unpatentable. Additionally, a mathematical formula is unpatentable because it “is merely a statement of a law of nature.” Similarly, medical diagnostic processes should be deemed as a category of patent-ineligible subject matter for numerous reasons. First, courts have repeatedly struck down patent claims to medical diagnostic processes unless they include a step of actually treating the patient. Second, allowing patents of medical diagnostic processes preempts the use of cheap medical diagnostics. Third, patenting medical diagnostic methods is counterintuitive to the purpose of the patent system itself. Finally, inventors can still protect their inventions in a meaningful way even if medical diagnostic processes were deemed patent-ineligible. Thus, in order to reduce medical costs and further the goals of the patent system while still favoring the investments of the inventors, medical diagnostic processes should be deemed prima facia ineligible under 35 U.S.C. § 101.

One of the major requirements for patentability is meeting subject matter eligibility under 35 U.S.C. § 101. Under this requirement, something is patentable if it falls within one of the four statutory categories of invention: processes, machines, manufactures, and compositions of matter.  “[A] process is a mode of treatment of certain materials to produce a given result.” A machine patent covers “what a device is, not what a device does.” “A manufacture patent is for items generated via large-scale manufacturing or wholesale systems, within which they are wholly fabricated.” Lastly, compositions of matter patents are described as “all compositions of two or more substances and . . . all composite articles, whether they be the results of chemical union, or of mechanical mixture, or whether they be gases, fluids, powders or solids.” Case law has carved out judicial exceptions that do not fall within these categories, such as abstract ideas and laws of nature. Claims solely directed to these exceptions are prima facie ineligible for patents. Courts have expanded the exceptions to capture claims that are not solely directed to a pre-existing exception under the Alice/Mayo framework.

Under the Alice/Mayo framework, there are two steps to determine whether a claim is eligible to be patented under § 101. First, one must determine whether the claim is directed to a judicial exception. If it is not, then the claim is eligible under § 101. If it is directed to an exception, then one must further analyze whether the claim recites additional elements that amount to significantly more than the judicial exception, in order to rebut the presumption of unpatentability based on the exception. If the claim recites additional claim elements to elevate the claim to significantly more than the exception, then the claim is patentable. Examples of limitations that amount to significantly more than the exception include improvements to computer function, transforming an article to a different state or thing, and applying the exception with a particular machine. If the additional limitations do not elevate the claim to significantly more than the judicial exception, then the claim is not patentable. Since medical diagnostic methods often include some combination of laws of nature, abstract ideas, or natural phenomena, such methods may be directed to a judicial exception under the Alice/Mayo framework.

A pattern in recent court decisions indicates that regardless of the level of specificity with which a law of nature or abstract idea is limited, a claim may overcome the hurdle of being directed to a judicial exception by including steps or elements outside of the judicial exception that are new and useful. Often, even detailed steps of data output and presentation are not enough, but what is significantly more effective in overcoming the presumption of unpatentability than the abstract idea is applying that abstract idea or law of nature to perform something practical and tangible. For medical diagnostic processes, this amounts to a step of treatment that incorporates the diagnosed condition. Thus, ultimately, what is patented is not a medical diagnostic method, but a medical treatment method. Therefore, medical diagnostic methods should be prima facie unpatentable.

The prior art searching that the patent examiner must undergo to analyze the claim under the Berkheimer precedent further compounds patent prosecution. The examiner must ordinarily conduct a review—called the prior art search—of all publications that could have disclosed the claimed invention in order to determine whether the subject matter is novel and non-obvious. Under post-Berkheimer analysis, questions of whether something is routine and conventional in the field are questions of fact that must be supported by prior art evidencing their routineness, which cuts against patentability. Thus, the examiner must determine whether prior art supports the routineness of claim elements, in addition to prior art searching for novelty and non-obviousness and conducting the basic subject matter eligibility analysis under the Alice/Mayo framework. Therefore, in the pursuit of efficiency at the United States Patent and Trademark Office (USPTO), diagnostic methods should categorically be classified as prima facie unpatentable.

Also, allowing inventors to patent medical diagnostic processes is counter to the purpose of the patent system itself. The goal of the patent system is to provide the inventor with a temporary monopoly for his or her investment of time and effort in exchange for the publicizing of important scientific knowledge for further innovation and technological development. Patenting medical diagnostic methods counteracts this goal because inventors can essentially continue their monopoly by adding a more specific limitation to their next patent. This stifles development because inventors are not motivated to create new ideas if they can extend their monopoly by adding insignificant limitations.

For example, consider a diagnostic method patent that is granted with a claim comprising A and B. An individual is precluded from practicing the medical diagnostic method comprising A and B for the life of the patent. Near the end of the patent’s life, the inventor is entitled to another, new patent for a diagnostic method comprising A, B, and C, so long as C is sufficiently inventive over the prior art such that the combination of A, B, and C would not have been obvious to one of ordinary skill in the art at the time of filing. Now, even after the end of the lifetime of the patent comprising A and B, the individual is still precluded from practicing the method comprising A and B because it is encompassed by the newly patented method, which still comprises the original elements of A and B, in addition to the new element, C.

This practice, known commonly as evergreening, is a problem among patents in general, but is particularly problematic for medical diagnostic processes. Specifically, even if the individual wants to practice the cheaper, older method of diagnosing a medical condition, he or she is prevented from doing so by the effective extension of the original patent’s term by the addition of a new limitation. Thus, the patenting of medical diagnostic methods prevents access to cheaper, yet still effective, methods of medical diagnosis.

Even if diagnostic method claims are deemed prima facia ineligible, as I argue they should be, inventors can still protect their inventions using alternate methods. One way to do this is by including a narrowing limitation in the claim that includes a step of treatment or therapy based on the diagnosed condition. As discussed above, this effectively makes the claim one of treating a condition and not detecting it, but the inventor’s core invention is still protected by patent with the addition of a relatively insignificant limitation.

Another way to protect the invention is to claim the specific device that is applying the diagnostic method rather than the method itself. Since the addition of the device adds specific structural limitations, it is less likely that the claim as a whole will still be deemed to be directed to an abstract idea or a law of nature.

One additional way to protect the inventor’s hard work is by considering copyright protection in lieu of patent protection. This technique is more applicable than patenting for diagnostic methods implemented on a computer where the true invention lies in the programming itself. By protecting the software that the inventor invested time and effort into, the intellectual property protection services both the inventor and the public. Additionally, the duration of copyright protection is longer than patent protection. Also, acquiring copyright protection precludes the use of the software in any type of computer, which gives the protection a larger breadth than trying to claim it within a specific diagnostic structure in a patent.

Ultimately, it would be more beneficial to designate medical diagnostic processes as a category of patent-ineligible inventions. This designation would improve the timing and efficiency of prosecuting a patent application based on patterns in case law, while still allowing inventors to protect their inventions in alternate ways. Finally, such a designation would promote the goals of the patent system by encouraging useful innovation in the medical field.


AngelinePremrajHeadshotAbout the Author: Angeline Premraj is a rising third-year law student at Cornell Law School and Note Editor for the Cornell Journal of Law and Public Policy. She earned her B.S. and M.S. in Biomedical Engineering from The Catholic University of America and is interested in policy issues relating to intellectual property law. This summer, she will be working at Finnegan, Henderson, Farabow, Garrett & Dunner LLP in Washington, D.C.


Suggested Citation: Angeline Premraj, Diagnostic Methods as a Category of Patent-Ineligible Subject Matter, Cornell J.L. & Pub. Pol’y, The Issue Spotter, (June 22, 2020), http://jlpp.org/blogzine/diagnostic-methods-as-a-category-of-patent-ineligible-subject-matter/.