The Supreme Court of the United States, in the eagerly awaited decision in Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., No. 95-728, slip op. at 1 (Sup. Ct. March 3, 1997), unanimously upheld the continued applicability of the "doctrine of equivalents" to issues of claim infringement in patent cases (Justices Ginsburg and Kennedy joined in a concurring opinion). Based on its analysis clarifying the proper scope of the doctrine, the Court reversed the decision of the Court of Appeals for the Federal Circuit, in which the Federal Circuit had affirmed a jury verdict finding infringement under the doctrine (see our September 1995 IP Report), and remanded for further proceedings consistent with its opinion. Id. at 22.
In the opinion delivered by Justice Thomas, the Supreme Court rejected the Petitioner's argument that the doctrine of equivalents, as set out by the Court in Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605 (1950), did not survive the 1952 revisions of the Patent Act, because it is inconsistent with the aspects of that Act relating to: (1) the requirement of definiteness in claim drafting under 35 U.S.C. 112, 2; (2) the patent reissue process for correcting mistakes in claim drafting; (3) the primacy of the Patent and Trademark Office ("PTO") in determining the scope of the patent through the patent prosecution process; and (4) the specific inclusion of the concept of "equivalency" in the section of the Act regarding "means" claiming, 35 U.S.C. 112, 6. Id. at 6.
The Court found that the 1952 Patent Act is not materially different from the preceding 1870 Patent Act in terms of claiming, reissue, and the role of the PTO, and that the 1950 Graver Tank decision addressed and rejected all three arguments against the doctrine of equivalents at that time. Id. at 6-7. With regard to Petitioner's fourth argument, the Court found that Section 112, 6, allowing "means" claiming, was enacted by Congress as a specific response to the decision in Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1 (1946) precluding functional language at the exact point of novelty. The Court reasoned that while this provision permitted "means" claiming, the phrase referring to "equivalents" was intended as a prophylactic to narrow the application of broad literal "means" elements, and did not by negative inference preclude the doctrine of equivalents as applied where there is no literal infringement. Id. at 8-9.
The Court concluded that "the lengthy history of the doctrine of equivalents strongly supports adherence to our refusal in Graver Tank to find that the Patent Act conflicts with that doctrine." Id. at 9.
In an effort to reconcile the admitted conflict between the doctrine of equivalents and the "definitional and public-notice functions of the statutory claiming requirement," the Court issued several mandates intended to clarify the scope of the doctrine. Id. at 9.
First, the Court held that the doctrine of equivalents must be applied to individual elements of the claim, not to the invention as a whole, to ensure that the doctrine is not allowed such "broad play as to effectively eliminate that element in its entirety." Id. at 10.
Second, the Court held that a claim element limitation added by amendment creates a rebuttable presumption that the "PTO had a substantial reason related to patentability" for requiring the amendment. The patentee has the burden of rebutting the presumption by establishing an appropriate reason for the added limitation other than to secure patentability of the claimed subject matter. If the patentee is unable to satisfy its burden, prosecution history estoppel will bar the application of the doctrine of equivalents as to that element. Id. at 14.
Third, the Court held that there is "no basis for treating an infringing equivalent any differently than a device that infringes the express terms of the patent." The Court thus found that intent should play no role in an objective approach to the application of the doctrine of equivalents. The Court's holding that the application of the doctrine requires no proof of intent precludes any requirement of an "equitable threshold" as a prerequisite for application of the doctrine. Similarly, the Court found that evidence relating to copying or efforts to design around an existing patent are not helpful in determining equivalence. The Court noted, however, that evidence of "independent experimentation" would likely be probative of a skilled artisan's knowledge or lack of knowledge of the interchangeability of substitutes for a claim element in determining whether that substitute is equivalent. Id. at 16-18.
Fourth, the Court held that the proper time for evaluating equivalency "is at the time of infringement, not at the time the patent was issued." This holding implicitly rejected the Petitioner's argument that the doctrine of equivalents should be limited to only equivalents that are disclosed within the patent itself. Id. at 18.
Fifth, the Court held that the "linguistic framework" or test used to determine equivalency must enlighten the essential inquiry, "Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?" The Court stated that different tests may be more or less suited to different cases, and that it was best left to the Federal Circuit to refine the formulation of the test for equivalence on a case-by-case basis. Id. at 21-22.
Lastly, the Court declined to review the Federal Circuit's holding that equivalency was properly a fact issue for a jury, rather than a question of law for a judge. The Court stated that its resolution of the proper role of the jury in deciding equivalency was not necessary to its deciding the questions presented regarding the scope of the doctrine of equivalents. The Court did state that there was ample precedent to support the Federal Circuit's holding, and that nothing in its recent Markman decision regarding claim interpretation "necessitated a different result than that reached by the Federal Circuit." Id. at 19-20.
In the case before it, the Court found that in view of its holdings clarifying the requirements under the doctrine of equivalents, particularly with regard to the application of prosecution history estoppel, and the absence on the record of the reason for a claim element limitation added by amendment, the case should be remanded to the Federal Circuit for further proceedings consistent with its opinion. Id. at 22.
The practical result of the Supreme Court's decision in Warner-Jenkinson is that the doctrine of equivalents will continue to be applied by the jury, in jury cases, without regard to the intent of the accused infringer. Emphasis should be on an element-by-element consideration of equivalency as of the time of infringement, and not on the equivalency of the accused product or process to the patented invention as a whole. Further, the patentee in an infringement suit is now saddled with the burden of overcoming a rebuttable presumption that any limitations to claim elements added by amendments required by the PTO during prosecution relate to patentability and bar application of the doctrine of equivalents to the relinquished subject matter of that element.