Talk:Warner-Jenkinson Company v. Hilton Davis Chemical Co., 520 US 17 (1997)
Patentee brought infringement action against competitor, alleging that competitor's ultrafiltration method for purifying dye infringed patented method under doctrine of equivalents.
The Supreme Court, Justice Thomas, held that: (1) doctrine of equivalents is not inconsistent with Patent Act; (2) doctrine of equivalents must be applied to individual elements of patent claim, not to invention as a whole; (3) prosecution history estoppel does not apply whenever patent claim has been amended during application process, regardless of reasons for change; (4) patentee's addition of lower pH limit during application process did necessarily preclude application of doctrine of equivalents as to that element; (5) remand was required to determine whether reason for amending patent claim to add lower pH limit was sufficient to avoid prosecution history estoppel; (6) doctrine of equivalents does not require proof of intent; (7) doctrine of equivalents is not limited to equivalents disclosed within patent itself. Reversed and remanded.
(c) The determination of equivalence should be applied as an objective inquiry on an element-by-element basis. The Court is concerned that the doctrine, as it has come to be broadly applied since Graver Tank, conflicts with the Court's numerous holdings that a patent may not be enlarged beyond the scope of its claims. The way to reconcile the two lines of authority is to apply the doctrine to each of the individual elements of a claim, rather than to the accused product or process as a whole. Doing so will preserve some meaning for each of a claim's elements, all of which are deemed material to defining the invention's scope. So long as the doctrine does not encroach beyond these limits, or beyond related limits discussed in the Court's opinion, infra, at 1049-1051, 1053-1054, n. 8, and 1054, it will not vitiate the central functions of patent claims to define the invention and to notify the public of the patent's scope. Pp. 1048-1049.
Nearly 50 years ago, this Court in Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 70 S.Ct. 854, 94 L.Ed. 1097 (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.
“What constitutes equivalency must be determined against the context of the patent, the prior art, and the particular circumstances of the case. Equivalence, in the patent law, is not the prisoner of a formula and is not an absolute to be considered in a vacuum. It does not require complete identity for every purpose and in every respect. In determining equivalents, things equal to the same thing may not be equal to each other and, by the same token, things for most purposes different may sometimes be equivalents. Consideration must be given to the purpose for which an ingredient is used in a patent, the qualities it has when combined with the other ingredients, and the function which it is intended to perform. An important factor is whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was.” Id., at 609, 70 S.Ct., at 856-857.
Petitioner's primary argument in this Court is that the doctrine of equivalents, as set out in Graver Tank in 1950, did not survive the 1952 revision of the Patent Act, 35 U.S.C. § 100 et seq., because it is inconsistent with several aspects of that Act. In particular, petitioner argues: (1) The doctrine of equivalents is inconsistent with the statutory requirement that a patentee specifically “claim” the invention covered by a patent, § 112; (2) the doctrine circumvents the patent reissue process-designed to correct mistakes in drafting or the like-and avoids the express limitations on that process, §§ 251-252; (3) the doctrine is inconsistent with the primacy of the Patent and Trademark Office (PTO) in setting the scope of a patent through the patent prosecution process; and (4) the doctrine was implicitly rejected as a general matter by Congress' specific and limited inclusion of the doctrine in one section regarding “means” claiming, § 112, ¶ 6.
Absent something more compelling than the dubious negative inference offered by petitioner, 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. Congress can legislate the doctrine of equivalents out of existence any time it chooses. The various policy arguments now made by both sides are thus best addressed to Congress, not this Court.
B We do, however, share the concern of the dissenters below that the doctrine of equivalents, as it has come to be applied since Graver Tank, has taken on a life of its own, unbounded by the patent claims. There can be no denying that the doctrine of equivalents, when applied broadly, conflicts with the definitional and public- notice functions of the statutory claiming requirement.
Each element contained in a patent claim is deemed material to defining the scope of the patented invention, and thus the doctrine of equivalents must be applied to individual elements of the claim, not to the invention as a whole. It is important to ensure that the application of the doctrine, even as to an individual element, is not allowed such broad play as to effectively eliminate that element in its entirety. So long as the doctrine of equivalents does not encroach beyond the limits just described, or beyond related limits to be discussed infra, this page and 1050-1051, 1053, n. 8, and 1054, we are confident that the doctrine will not vitiate the central functions of the patent claims themselves.
In our view, holding that certain reasons for a claim amendment may avoid the application of prosecution history estoppel is not tantamount to holding that the absence of a reason for an amendment may similarly avoid such an estoppel. Mindful that claims do indeed serve both a definitional and a notice function, we think the better rule is to place the burden on the patent holder to establish the reason for an amendment required during patent prosecution. The court then would decide whether that reason is sufficient to overcome prosecution history estoppel as a bar to application of the doctrine of equivalents to the element added by that amendment. Where no explanation is established, however, the court should presume that the patent applicant had a substantial reason related to patentability for including the limiting element added by amendment. In those circumstances, prosecution history estoppel would bar the application of the doctrine of equivalents as to that element. The presumption we have described, one subject to rebuttal if an appropriate reason for a required amendment is established, gives proper deference to the role of claims in defining an invention and providing public notice, and to the primacy of the PTO in ensuring that the claims allowed cover only subject matter that is properly patentable in a proffered patent application. Applied in this fashion, prosecution history estoppel places reasonable limits on the doctrine of equivalents, and further insulates the doctrine from any feared conflict with the Patent Act.
Winans v. Denmead, 15 How. 330, 343, 14 L.Ed. 717 (1854), we described the doctrine of equivalents as growing out of a legally implied term in each patent claim that “the claim extends to the thing patented, however its form or proportions may be varied.” Under that view, application of the doctrine of equivalents involves determining whether a particular accused product or process infringes upon the patent claim, where the claim takes the form-half express, half implied-of “X and its equivalents.”
“[T]he substantial equivalent of a thing, in the sense of the patent law, is the same as the thing itself; so that if two devices do the same work in substantially the same way, and accomplish substantially the same result, they are the same, even though they differ in name, form, or shape.” If the essential predicate of the doctrine of equivalents is the notion of identity between a patented invention and its equivalent, there is no basis for treating an infringing equivalent any differently from a device that infringes the express terms of the patent. Application of the doctrine of equivalents, therefore, is akin to determining literal infringement, and neither requires proof of intent.
The Federal Circuit explained this factor by suggesting that an alleged infringer's behavior, be it copying, designing around a patent, or independent experimentation, indirectly reflects the substantiality of the differences between the patented invention and the accused device or process. According to the Federal Circuit, a person aiming to copy or aiming to avoid a patent is imagined to be at least marginally skilled at copying or avoidance, and thus intentional copying raises an inference-rebuttable by proof of independent development-of having only insubstantial differences, and intentionally designing around a patent claim raises an inference of substantial differences. This explanation leaves much to be desired. At a minimum, one wonders how ever to distinguish between the intentional copyist making minor changes to lower the risk of legal action and the incremental innovator designing around the claims, yet seeking to capture as much as is permissible of the patented advance.
The known interchangeability of substitutes for an element of a patent is one of the express objective factors noted by Graver Tank as bearing upon whether the accused device is substantially the same as the patented invention. Independent experimentation by the alleged infringer would not always reflect upon the objective question whether a person skilled in the art would have known of the interchangeability between two elements, but in many cases it would likely be probative of such knowledge.
See, e.g., Union Paper-Bag Machine Co. v. Murphy, 97 U.S., at 125 (“[I]n determining the question of infringement, the court or jury, as the case may be, ... are to look at the machines or their several devices or elements in the light of what they do, or what office or function they perform, and how they perform it, and to find that one thing is substantially the same as another, if it performs substantially the same function in substantially the same way to obtain the same result”); Winans v. Denmead, 15 How., at 344 (“[It] is a question for the jury” whether the accused device was “the same in kind, and effected by the employment of [the patentee's] mode of operation in substance”).
An 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 element plays a role substantially different from the claimed element.