The doctrine of equivalents arises in the context of an infringement action. If an accused product or process does not literally infringe a patented invention, the accused product or process may be found to infringe under the doctrine of equivalents. The essential objective inquiry is: “Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?” Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17, 41 USPQ2d 1865, 1875 (1997). In determining equivalence, “[a]n analysis of the role played by each element in the context of the specific patent claim will thus inform the inquiry as to whether a substitute element matches the function, way, and result of the claimed element, or whether the substitute plays a role substantially different from the claimed element.” 41 USPQ2d at 1875.
35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, permit means- (or step-) plus-function limitations in claims to combinations, “with the proviso that application of the broad literal language of such claims must be limited to only those means that are ‘equivalent’ to the actual means shown in the patent specification. This is an application of the doctrine of equivalents in a restrictive role, narrowing the application of broad literal claim elements.” 41 USPQ2d at 1870. Accordingly, decisions involving the doctrine of equivalents should be considered, but should not unduly influence a determination under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, during ex parte examination. See MPEP § 2183.