In the most straightforward case of infringement of a method patent, all of the required steps of the claim are performed by the same actor. For example, a patent directed to a semiconductor fabrication process might require the separate steps of forming several layers, and each of those steps might be performed by a foundry that is manufacturing semiconductors. In that case, the foundry would be a direct infringer under 35 U.S.C. §271(a). In another example, a patent might be directed to a method of performing a certain surgical procedure, and each of the steps might be performed by physicians who conducted the procedure on their patients. Once again, each of the individual physicians would be a direct infringer.
Because it is not always practicable or desirable to enforce a patent against direct infringers, however, U.S. patent law also allows a patent owner to sue indirect infringers in certain circumstances. In the second situation given above, for example, the patent might be owned by the manufacturer of a piece of high-tech equipment that can be used to conduct the surgical procedure. As a practical matter, it would not be possible for the manufacturer to individually sue all of the physicians conducting the procedure, and even if it were possible, the manufacturer understandably might not wish to do so, given that the physicians are probably customers or potential customers. More likely, the manufacturer would want to enforce its patent against another manufacturer who makes competing equipment. Depending on a number of factors, including, among other things, the specifics of the patent and the structure and operation of the accused equipment, the patent owner might be able to succeed in doing so. Specifically, if the competitor encourages its customer physicians to use its equipment in an infringing manner and possesses a requisite level of intent that their customer physicians infringe, it would be liable for induced infringement under 35 U.S.C. §271(b).
