United States: Festo: The Beginning Of The End For Doctrine Of Equivalents

In Festo, (Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558 (Fed. Cir. 2000)), the Federal Circuit essentially eliminated application of the Doctrine of Equivalents to elements of claims that have been amended in prosecution before the U.S. Patent and Trademark Office ("PTO").

By way of review; a patent claim is infringed only if all elements recited in the claim are found either literally or by equivalents in the accused infringing product or process. The Doctrine of Equivalents is generally applied to determine whether a particular element, not found literally in the accused product or process, is present in some equivalent form such that the accused infringer should still be held liable. A variety of tests have been defined by the Federal Circuit for determining whether an aspect of the accused product or process is equivalent to corresponding recited elements in the patent claim at issue. The Supreme Court has held in Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997) that "prosecution history estoppel" may limit the application of the Doctrine of Equivalents. Prosecution history estoppel is an equitable doctrine that estops a patent holder from asserting a scope of protection for a claim that has been surrendered in the "prosecution history" before the PTO. The prosecution history is, in essence, all communications between the patent holder (applicant) and the PTO during the pendency of the patent at issue. The Supreme Court held in Warner that such prosecution history estoppel may limit or completely bar application of the Doctrine of Equivalents to those elements of a patent claim affected by such prosecution history.

In Festo, the Federal Circuit found that a number of issues relating to application of the Doctrine of Equivalents remain unsettled by the Supreme Court's decision in Warner. Specifically in Festo, the Federal Circuit rules on four questions - namely:

1. For the purposes of determining whether an amendment to a claim creates prosecution history estoppel, is "a substantial reason related to patentability," Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 33, 117 S. Ct. 1040, 137 L. Ed. 2d 146 (1997), limited to those amendments made to overcome prior art under  102 and  103, or does "patentability" mean any reason affecting the issuance of a patent?
2. Under Warner-Jenkinson, should a "voluntary" claim amendment - one not required by the examiner or made in response to a rejection by an examiner for a stated reason - create prosecution history estoppel?
3. If a claim amendment creates prosecution history estoppel, under Warner-Jenkinson what range of equivalents, if any, is available under the doctrine of equivalents for the claim element so amended?
4. When "no explanation [for a claim amendment] is established," Warner-Jenkinson, 520 U.S. at 33, 117 S. Ct. 1040, thus invoking the presumption of prosecution history estoppel under Warner-Jenkinson, what range of equivalents, if any, is available under the doctrine of equivalents for the claim element so amended?

The Court ruled on the four issues en Banc in an eight to four decision as follows:

The Court held:

The Court clarifies that amendments for "a substantial reason related to patentability" include claim amendments in response to art-based rejections (35 U.S.C. §§102 and 103) as well as non-art-based rejections from the PTO such as non-statutory subject matter (35 U.S.C. §101), written description lack of enablement or best mode (35 U.S.C. §112, first paragraph) and lack of clarity in the claim language (35 U.S.C. §112, second paragraph).

It should be noted that an estoppel is raised only if the amendment narrows the affected elements of the claim. No estoppel is raised by an amendment the does not narrow the claim element.

A question remains as to whether an estoppel is raised if a claim is not legally rejected by the PTO but rather is "objected to" due to some informality. It may be argued that an amendment in response to an objection is not in response to "a substantial reason related to patentability." It does seem clear from the facts of Festo that the Court would view a substitute claim replacing a canceled, rejected claim the same as an amendment of the rejected claim if the substitution is in response to "a substantial reason related to patentability." The Court appears to look past such form over substance in this regard.

The Court states: "Voluntary claim amendments are treated the same as other amendments." In other words, it is irrelevant whether an amendment is in response to a rejection by the Examiner or is volunteered by the patent holder. If a voluntary amendment narrows an element of a claim and relates to statutory requirements for patentability, then such a voluntary amendment also gives rise to an estoppel.

When an estoppel arises from a claim amendment (whether voluntary or responsive to a rejection) the Court in Festo clearly states:

When a claim amendment creates prosecution history estoppel with regard to a claim element, there is no range of equivalents available for the amended claim element. Application of the doctrine of equivalents to the claim element is completely barred (a "complete bar").

Where in the past there had been conflicting theories as to the proper application of the Doctrine of Equivalents, the Festo Court now makes clear that there is NO applicability of the Doctrine where an estoppel arises from the prosecution history as discussed above. Prior holdings of the Court had suggested a flexible approach to application of the Doctrine of Equivalents where prosecution history estoppel limited its applicability. Hughes Aircraft Co. v. United States, 717 F.2d 1351, (Fed. Cir. 1983) ("Hughes I"). Another early case, Kinzenbaw v. Deere & Co., 741 F.2d 383 (Fed. Cir. 1984), decided less than a year after Hughes I, took a much narrower view. The Kinzenbaw Court, in essence, determined that there was NO scope of equivalents afforded the amended claim.

Recognizing the confusion in trying to reconcile these two cases, the Festo Court makes clear that Hughes I is overturned by the Court's ruling in Festo. The Court asserts that the confusion generated in industry by the uncertainty in the scope of protection afforded a patent claim due to inconsistent application of the Doctrine of Equivalents may hinder technological advance. Amici Curiae briefs in the Festo case filed by no less than IBM, Kodak and Ford Motor Company support the Court's view that strict preclusion of the application of the Doctrine of Equivalents is preferred. The Court asserts that one important function of a patent is the "notice" function - that of clearly notifying the public as to the scope or protection afforded a patent holder. Such clear notice permits others in industry to more clearly understand the bounds of protection held by a patent holder. Such a clear understanding of the scope of protection permits business planning and fosters engineering development to invent around the scope of a present patent (to thereby further advance the useful arts).

Of further interest in Festo is the recognition by the Federal Circuit that means-plus-function style claims defined under 35 U.S.C. 112, paragraph six retain a measure of equivalency analysis defined by statute even if the Festo holding bars application of the Doctrine of Equivalents.

Even if the amendment that added the sealing ring element merely replaced the means-plus-function language with a recitation of the corresponding structure, the amendment had the effect of narrowing the scope of the claim. A claim element recited in means-plus-function language literally encompasses the corresponding structure and its equivalents. Laitram Corp. v. Rexnord Inc., 939 F.2d 1533, 1536, 19 USPQ2d 1367, 1370 (Fed. Cir. 1991). In contrast, a claim element that recites the corresponding structure does not literally encompass equivalents of that structure. Id. Thus, a claim amendment that replaces means-plus-function language with language reciting the corresponding structure narrows the literal scope of the claim.

In sum, prosecution history and claim styles now bear an even heavier burden on clearly defining the broadest scope of protection for the invention. The Doctrine of Equivalents has been severely curtailed by the Festo decision. In patent preparation and prosecution, the following tips may be helpful to retain broad protection in subsequent enforcement proceedings:

1. Explain the reason for any amendments in prosecution that are not directly in response to a substantial reason related to patentability.
2. Prepare a wide variety of patent claims having varying depths of detail. A seemingly narrow detailed claim (i.e., a "picture claim") allowed as filed may ultimately prove very valuable in enforcement since the broadest range of equivalence will be retained in such an un-amended claim.
3. Include means-plus-function style claims so as to assure at least statutory equivalence analysis will be retained in the claim infringement analysis.

Lastly, it is likely that Festo will petition for certiorari for further review of this matter at the Supreme Court. Especially in view of the strong dissents in this case, it is possible the Supreme Court will hear this matter further and possibly modify or reverse the holding of the Federal Circuit. Stay tuned!