About: Reverse doctrine of equivalents

The reverse doctrine of equivalents is a legal doctrine of United States patent law, according to which a device that appears to literally infringe a patent claim, by including elements or limitations that correspond to each element or limitation of the patent claim, nonetheless does not infringe the patent, because the accused device operates on a different principle. That is, "it performs the same or a similar function in a substantially different way." It has been said that "the purpose of the 'reverse' doctrine is to prevent unwarranted extension of the claims beyond a fair scope of the patentee's invention."