Infringement Under the Doctrine of Equivalents Law and Legal Definition

Doctrine of Equivalents is an equitable concept employed to prevent someone from getting the benefit of the invention by making a minor change that avoids literal infringement. Under the Doctrine of Equivalents, one infringes a claim where every element of the claim is expressly satisfied by a device, process, or composition of matter.

To prove infringement under the doctrine of equivalents, the patent holder must show that the accused device contains each limitation of the claim or its equivalent; an element in an accused product is equivalent to a claim limitation if the differences between the two are insubstantial to one of ordinary skill in the art. [Pactiv Corp. v. S.C. Johnson & Son, Inc., 2000 U.S. Dist. LEXIS 18877 (N.D. Ill. Nov. 27, 2000)].