Cite as: 520 U. S. 17 (1997)
Opinion of the Court
Justice Thomas delivered the opinion of the Court.
Nearly 50 years ago, this Court in Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U. S. 605 (1950), set out the modern contours of what is known in patent law as the "doctrine of equivalents." Under this doctrine, a product or process that does not literally infringe upon the express terms of a patent claim may nonetheless be found to infringe if there is "equivalence" between the elements of the accused product or process and the claimed elements of the patented invention. Id., at 609. Petitioner, which was found to have infringed upon respondent's patent under the doctrine of equivalents, invites us to speak the death of that doctrine. We decline that invitation. The significant disagreement within the Court of Appeals for the Federal Circuit concerning the application of Graver Tank suggests, however, that the doctrine is not free from confusion. We therefore will endeavor to clarify the proper scope of the doctrine.
I
The essential facts of this case are few. Petitioner Warner-Jenkinson Co. and respondent Hilton Davis Chemical Co. manufacture dyes. Impurities in those dyes must be removed. Hilton Davis holds United States Patent No. 4,560,746 ('746 patent), which discloses an improved purification process involving "ultrafiltration." The '746 process filters impure dye through a porous membrane at certain
H. Tribe and Jonathan S. Massey; and for the Ohio State Bar Association by Eugene P. Whetzel and Albert L. Bell.
Briefs of amici curiae were filed for the American Automobile Manufacturers Association by D. Dennis Allegretti, Phillip D. Brady, and Andrew D. Koblenz; for the American Intellectual Property Law Association by Robert J. Baechtold, Stevan J. Bosses, Nicholas M. Cannella, Charles L. Gholz, and Roger W. Parkhurst; for the Chemical Manufacturers Association by Robert A. Armitage and Michael P. Walls; and for the Licensing Executive Society (U. S. A. and Canada), Inc., by Gayle Parker and James W. Gould.
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