What is Doctrine of Equivalents?
While there are multiple ways to skin a cat (see discussion on indirect infringement and direct infringement here), patent infringement can occur in two forms. The first is literal infringement. Literal infringement is when every aspect of the claim is being infringed upon in much the same way the claim was written. The second one, more complex, is an infringement under the doctrine of equivalents. Under this doctrine, the patentee can argue infringement even if each and every claim element of the patent is not completely or identically present in the infringed invention. The purpose of the doctrine is to ensure that the infringer does not benefit from minor or insubstantial changes that may escape literal infringement.