Certain medical treatment methods occupy a unique position in U.S. patent law. Methods for medical treatment of human or animals, including surgery and other therapies as well as diagnostic tests, are patentable in the same way and under the same rules that other processes are patentable. In 1996, however, Congress, at the request of the House of Delegates of the American Medical Association and others, changed U.S. patent law so as to limit the ability of the owners of patents on certain medical procedures to enforce those patents when the medical procedures are practiced by medical practitioners. Thus, while the procedures are still patentable, they are not protected by the patents, in that the patentees cannot prevent certain medical practitioners from practicing them.
A new subsection (c) was added to 35 U.S.C. 287, that exempts from the definition of "patent infringement" a medical practitioner's performance of a medical activity on a human or a laboratory animal [35 U.S.C 287(c)]. The new subsection contains exemptions which effectively limit the term "medical activity" to surgical procedures or diagnostic procedures not involving drugs or reagents. For example, a medical activity does not include the use of a patented machine, manufacture or composition of matter, or the patented use of a composition of matter.
In the light of this change in U.S. patent law, the inventor(s) of a medical treatment method must, at a minimum, take care in how the method is claimed. If the effects of 35 U.S.C 287(c) cannot be avoided, the inventor(s) must decide whether to pursue patent protection of the procedure.