Warner-Jenkinson Co. v. Hilton Davis Chemical Co.

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Warner-Jenkinson Company, Inc. v. Hilton Davis Chemical Co.
Argued October 15, 1996
Decided March 3, 1997
Full case nameWarner-Jenkinson Company, Incorporated, et al. v. Hilton Davis Chemical Company
Citations520 U.S. 17 (more)
117 S. Ct. 1040; 137 L. Ed. 2d 146; 1997 U.S. LEXIS 1476; 65 U.S.L.W. 4162; 41 U.S.P.Q.2d (BNA) 1865; 97 Cal. Daily Op. Service 1540; 97 Daily Journal DAR 2249; 10 Fla. L. Weekly Fed. S 321
Case history
PriorHilton Davis Chem. Co. v. Warner-Jenkinson Co., 62 F.3d 1512 (Fed. Cir. 1995); cert. granted, 516 U.S. 1145 (1996).
The Doctrine of Equivalents is consistent with the 1952 revisions to the Patent Act and patentees may attempt to prove that an amendment was not made to be limiting. Reversed and remanded.
Court membership
Chief Justice
William Rehnquist
Associate Justices
John P. Stevens · Sandra Day O'Connor
Antonin Scalia · Anthony Kennedy
David Souter · Clarence Thomas
Ruth Bader Ginsburg · Stephen Breyer
Case opinions
MajorityThomas, joined by unanimous
ConcurrenceGinsburg, joined by Kennedy
Laws applied
Patent Act of 1952

Warner-Jenkinson Company, Inc. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997), was a United States Supreme Court decision in the area of patent law, affirming the continued vitality of the doctrine of equivalents while making some important refinements to the doctrine.[1]


The plaintiff Hilton Davis Chemical Co., a dyemaker, had developed an "ultrafiltration" process to purify dyes. An amendment to the patent had specified that a solution used in the process must have a pH level between 6.0 and 9.0. The amendment was filed in order to clarify that this patent did not overlap with a previously patented process that used a solution with a pH level above 9.0 - however, the plaintiff was unable to explain why the amendment stated a lower level of 6.0. The defendant had developed a process using a solution with a pH level of 5.0, which was outside the range of the plaintiff's patent.

The plaintiff sued for infringement, conceding that the defendant's process did not literally infringe, but relying on the doctrine of equivalents to support the claim of infringement. The defendant argued that the doctrine of equivalents was no longer appropriate for courts to use because Congress had made some changes to the patent statute after the Supreme Court's 1950 decision establishing the propriety of using the doctrine.


Is the doctrine of equivalents still in force? How is the plaintiff's amendment to figure into the problem?


The Court, in an opinion by Justice Clarence Thomas, held that the doctrine of equivalents had not been eliminated by changes to the patent statute. Instead, the Court determined that the United States Congress would have explicitly stated that they were eliminating the doctrine if that was their intent. The Court enunciated a test for amendments, finding that if the plaintiff can prove the reason for the amendment was not to limit the patent, then infringement was still possible. The case was remanded to the trial court to determine if the plaintiff could explain his lower pH limit.


Justice Ruth Bader Ginsburg wrote a concurring opinion, in which Justice Anthony Kennedy joined, expressing some concern about whether patentees would have sufficient notice that they must explain the reasons for their amendments. Nevertheless, they agreed with the remand to the lower court to establish the plaintiff's reason for setting a lower limit.

See also[edit]


  1. ^ Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). Public domain This article incorporates public domain material from this U.S government document.

External links[edit]