The Supreme Court of the United States held that the doctrine of equivalents is not inconsistent with the Patent Act; that the doctrine of equivalents is to be applied to individual elements of a patent claim as opposed to the invention as a whole; that prosecution history estoppel applies to all changes made to an application during prosecution in the form of a rebuttable presumption against the patentee that can be overcome with a sufficient showing that the change was not relevant to patentability.
Warner-Jenkinson Co., Inc. v. Hilton Davis Chem. Co., 117 S. Ct. 1040 (1997).
Charles H. Dougherty Jr.,
Patent Law - Infringement - Doctrine of Equivalents - Prosecution History Estoppel,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol36/iss1/10