8.3 Doctrine of Equivalents

Patents / Biotechnology / US Biotechnology Practice

In determining whether an infringement of a patent has occurred, it is not necessary that the infringement absolutely falls within the literal wording of the claim if the doctrine of equivalents applies. The doctrine can be traced back to the 1853 Supreme Court case of Winans v. Denmead. [194] The objective is to prevent "fraud on the patent". This doctrine was ratified in the 1950 Supreme Court decision of Graver Tank Mfg. Co. v. Linde Air Products Co. [195] Typically pioneer patents will be given a broader range of protection than an improvement patent. [196] Under Graver Tank the main formulation of the doctrine is that it is an infringement of a patent claim even if it is not literally infringed if the allegedly infringing device or process "performs substantially the same function in substantially the same way to achieve the same result" as the patented invention. [197]

The issue came before the Supreme Court again in 1997 in Warner-Jenkinson v. Hilton Davis [198]. This case followed a period in which many people felt that the doctrine of equivalents was being over used and that fear that something might be held to be an equivalent to what was claimed was having a chilling effect on investment and innovation. The Supreme Court upheld the viability of the doctrine but imposed two important limitations on its application. The first of these was that the doctrine is to be applied by determining whether the accused product or process contains elements identical or equivalent to each claimed element of the invention rather than viewing the accused product or process as a whole. The second was to enhance the role of prosecution history in limiting the scope of protection to be given under the doctrine. The Supreme Court stated that the burden is to be placed on the patentee to establish the reason for an amendment required during patent prosecution as not being required to establish the patentability of the claim. 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 amendment.

The second of these requirements has been applied vigorously by the Court of Appeal for the Federal Circuit. In the case of Festo v. Shoketsu Kinzoku KK, the Federal Circuit Court, when considering whether an amendment to a claim during prosecution would create an estoppel against a broad interpretation of that claim for purposes of determining infringement under the doctrine of equivalents, held that

(1) an amendment that narrows the scope of a claim for any reason related to the statutory requirements for a patent will give rise to prosecution history estoppel with respect to the amended claim element;

(2) a “voluntary” claim amendment that narrows the scope of the claim for a reason related to the statutory requirements for a patent will give rise to prosecution history estoppel as to the amended claim element;

(3) when a claim amendment creates prosecution history estoppel with respect to a claim element, there is no range of equivalents available for the amended claim element, thereby completely barring application of the doctrine of equivalents as to the amended element (“complete bar”) [199]; and

(4) failure to explain a claim amendment invokes a presumption of prosecution history estoppel, thereby providing no range of equivalents under the doctrine of equivalents as to a claim element that was affected by such an amendment.

It was also held that these criteria apply irrespective of whether the amendment was made by restricting a particular claim during prosecution or by replacing a broad claim with a narrower one if the purpose of the replacement was to present a claim that lacked the problems which resulted in the claim that was being replaced being unpatentable.

The Supreme Court has agreed to review the Federal Circuit’s decision in Festo on certiorari and oral argument was due to take place on January 8, 2002. [200]

8.3.1 Dealing with Festo v. Shoketsu Kinzoku KK

Unless and until it is overruled on appeal, the Festo decision creates some practical problems in drafting patent applications for use in the United States. The simple answer to how to avoid limitation on the application of the doctrine of equivalents after Festo is to avoid limiting claims during prosecution for reasons relating to patentability. How is this to be accomplished? One way would be by filing multiple applications. However, this may be impracticable in many circumstances. A number of other possibilities come to mind:

(1) Make sure that before the first set of claims is filed in a non-provisional application the prior art has been searched as thoroughly as possible. If the application claims priority from a provisional application or a foreign application it may be desirable to use the year between the filing of the first application and the filing of the non-provisional application to supplement any searches that were done prior to filing the initial application. A full appreciation of the prior art should help in drafting claims that do not need to be amended during prosecution.

(2) Make sure that the claims are clear and fully enabled before they are filed. Amendments to claims to meet the requirements of 35 USC § 112 paragraph 1 (the requirements for an enabling disclosure and a sufficient written description) or paragraph 2 (clarity of claims) are just as likely to cause the invocation of a prosecution history estoppel as an amendment to avoid the prior art.

(3) Where possible keep a continuation application pending throughout the life of the patent so that, when an infringement outside the literal scope of the claims that have been granted is discovered, one can write claims that are tailored to the situation and one hopes will not require amendment during prosecution. In this context it may be worthwhile filing both a U.S. non-provisional application, if this does not already exist, and an International Application under the Patent Cooperation Treaty (PCT ) designating the United States at the end of the convention year. In this case, if the requirements of Chapter II of the PCT are met, the PCT designation of the United States can remain inactive until thirty months from the claimed priority date and one can see how the prosecution of the non-provisional application has fared before deciding what claims, if any, one wishes to present for prosecution in an application arising from U.S. national phase entry from the PCT application.

(4) When amending claims during prosecution if possible make an argument for the patentability of the claims prior to amendment and state that the reason for limitation is for commercial, financial or other reasons not related to patentability;

(5) File the application with at least some claims that one is confident will be allowed without amendment. Some have suggested that the application be filed with only narrow claims. This could, however, back-fire if the Federal Circuit expands its reasoning in Sage Products. [201] Possibly the safer way is to file narrow claims initially and then when these are allowed, file broader claims either in the same application or a continuation application.

(6) Consider the possibility of using multiply dependent claims to create a large number of claim moieties to cover multiple aspects of the invention in relatively narrow terms. (Each combination covered by a multiply dependent claim will have to be paid for and be treated as a separate claim. When used in the United States, a multiply dependent claim may not depend on another multiply dependent claim.

(7) Where the nature of the invention permits, use claims defining various elements in means plus function form. The Federal Circuit Court of Appeals has held that when considering claim elements in this form, application of the statutory requirement that they be construed to cover structures described in the specification and the structural equivalents thereof is not an application of the doctrine of equivalents but simply a matter of literal interpretation of the claim by applying the requirements of 35 USC § 112 paragraph 6.

(8) When entering the United States national phase on an International Patent Application filed under the PCT, if one wishes to file new claims, consider making the first application actually submitted to the USPTO a continuation of the International application rather than a direct national phase entry.

[194] 56 U.S. (15 How) 330 (1853).

[195] 339 U.S. 605, 85 USPQ 328.

[196] Autogiro Co of America v. United States, 384 F.2d. 391 155 USPQ 697 (Ct. Clms. 1967).

[197] See, for example Molinaro v. Hart Electronics of Scranton, 209 USPQ 735 M.D. Pa. 1980). The exact scope of protection given by means of the doctrine of equivalents tends to vary depending upon the circumstances. Pioneer patents are normally given broader protection than patents for later improvements. There are, however, limits on the extent of protection given even to pioneer patents as is shown by the Federal Circuit's decision in Texas Industries v. ITC, 231 USPQ 833.

[198] 41 USPQ2d 1865, 520 U.S. 17.

[199] This part of the decision overruled some earlier Federal Circuit decisions, such as Litton Sys. Inc v. Honeywell Inc., 145 F.3d. 1472, 47 USPQ2d 1106 (Fed. Cir. 1998), where the Court it had adopted a “flexible” application of the doctrine of prosecution history estoppel.

[200] 00-1543 June 18, 2001, 2001 WL 378251. Two issues are before the Supreme Court: 1) whether prosecution history estoppel arises when amendments are made for reasons related to patentability other than to distinguish the prior art and 2) whether, when an amendment has been made during prosecution this results in a total bar on the application of the doctrine of equivalents to that element of the claim or whether the limitation of the application of the doctrine of equivalents should be tailored to take account of the particular reason for making the amendment.

[201] Sage Products Inc v. Devon Industries Inc., 126 F.3d 1420, 44 USPQ2d 1103 (Fed. Cir. 1997). In this case, the Federal Circuit emphasized the importance of the notice function of patent claims. The Court noted "as between the patentee who had a clear opportunity to negotiate broader claims but did not do so and the public at large, it is the patentee who must bear the cost of its failure to seek protection for foreseeable alteration of its claimed structure."

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