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Late last year, the act of amending patent applications before the Patent and Trademark Office became a lot trickier. It’s not overstating the case to say that amending patent claims without due consideration for Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. runs the risk of rendering the intellectual property protected nearly worthless. Next question: What can patent practitioners do to prevent this from happening? We have 10 suggestions, but first let’s review the history: In Festo, the U.S. Circuit Court of Appeals for the Federal Circuit said that essentially all amendments narrowing a claim will now be presumed to relate to issues of patentability. And that means that, under earlier decisions on the doctrine of prosecution history estoppel, patent owners will not be able to invoke the doctrine of equivalents to protect their intellectual property from infringement. Practitioners learn in Patent Law 101 that a patent owner makes out a case of literal infringement by showing that the defendant’s device contains each element of at least one patent claim. If the device lacks even one element, then it does not literally infringe. But what’s to prevent a copyist from slightly altering one element of the claim, thereby avoiding literal infringement and successfully stealing patented technology? To address this problem, the courts early on in the development of our patent law crafted the doctrine of equivalents. To find infringement under the doctrine of equivalents, the fact-finder must discern only “insubstantial differences” between the patented device and the device accused of infringement, wrote the Federal Circuit in its 1995 decision in Hilton Davis Chemical Co. v. Warner Jenkinson Co. But under the doctrine of prosecution history estoppel, the actions of the applicant during patent prosecution can limit the scope of claims later asserted under the doctrine of equivalents in an infringement lawsuit. If the applicant amends the claims during prosecution to avoid some prior art that would otherwise defeat patentability and thus surrenders certain territory, then the applicant cannot recapture that territory later under the doctrine of equivalents. It has been presumed since Hilton Davis that an amendment relates to patentability — and thus estops the applicant from reclaiming the relinquished territory — unless the prosecution history shows otherwise. If the patent owner can show that the reason for the amendment was unrelated to issues of patentability, then the court has to determine whether the reason is sufficient to overcome prosecution history estoppel. In November 2000, the Federal Circuit unexpectedly devised a new way to analyze the doctrines of equivalents and prosecution history estoppel. According to Festo, the phrase “substantial reason related to patentability” goes beyond amendments made to overcome prior art under 35 U.S.C. �102 and �103 (requiring the subject matter of the patent to be novel and nonobvious). An amendment narrowing the scope of a claim for any reason related to any statutory requirement of patentability will give rise to prosecution history estoppel. Furthermore, when a claim amendment creates prosecution history estoppel, no range of equivalents is available for the amended claim element. And neither is any range of equivalents available for the amended element if the presumption of prosecution history estoppel under Hilton Davis is invoked and not rebutted. In light of Festo, patent practitioners will have to work harder than ever before to avoid creating prosecution history estoppel. The following suggestions may help: � Draft Strong Original Claims. Applicants should try to draft claims that will not have to be amended. They might need to conduct more extensive searches of the prior art than in the past. The common practice of drafting a fairly broad claim and then amending it to whatever the examiner will allow is now too risky. � Make Sure That All Claim Terms Are Necessary, Defined Fully, and Used Consistently. Generally, claim terms are given their ordinary and accustomed meaning unless the patentee has chosen to be his own lexicographer by clearly and explicitly defining a claim term. If a word has multiple common definitions or a special definition in the art as well as an ordinary meaning, applicants should specify the definition intended. They should try to have an identifiable definition for each claim term, including any transition terms. Note that in Union Pacific Resources Co. v. Chesapeake Energy Corp. (Fed. Cir. 2001), the patentee’s failure to provide definitions of two claim terms resulted in the claims being held invalid. Once each claim term is explicitly defined, applicants should make sure that the term is used consistently. As the patent owner in Aqua-Aerobic Systems Inc. v. Aerators Inc. (Fed. Cir. 2000) unhappily discovered, different terms and phrases can be construed differently, even if the drafter intended them to have the same meaning. Applicants should also try to avoid unnecessary words in the claims or in the definitions provided in the written description. Needless words will only distract from the applicant’s meaning. � Thoroughly Explore All Possible Embodiments of the Invention. Although this may require a more extensive search of the prior art than in the past, a full range of claims will serve applicants in two ways. First, they may be able to avoid amending a claim during patent prosecution. Second, applicants will avoid running into the problem of having a disclosed but unclaimed embodiment in the patent application. Disclosed but unclaimed embodiments should be considered “dedicated to the public,” as the Federal Circuit said in Maxwell v. J. Baker Inc. (1996). � Make the Reason for an Amendment Explicit. If applicants make an amendment for a reason that is unrelated to patentability, they should try to make that reason explicit in the amendment. If they do not, the Hilton Davis presumption will operate, and if the presumption goes unrebutted, no range of equivalents will be allowed. � Amend Precisely. Applicants should refrain from amending claims more narrowly than necessary to avoid the prior art. When they must amend a generic or “genus” claim to avoid a “species” that appears in the prior art, they do not have to limit the claims to a set of species expressly disclosed in the application. Rather, they have a right to amend the generic claim to exclude the prior-art species (even though that species is not explicitly disclosed in the specification) without otherwise reducing the scope of the generic claim. Also, if an amendment is necessary, applicants should consider singling out the particular claim element to be narrowed. The court in Festo indicated that the complete bar of prosecution history estoppel only applied to the amended elements of a claim. � Disclose a Spectrum in the Specification. Particularly for parameters such as ranges of temperature, composition, etc., the specification should disclose a spectrum of values, so that amendments that slightly narrow the claims will have support in the “written description” required by 35 U.S.C. �112. Note that the U.S. Court of Customs and Patent Appeals ruled in In re Wertheim (1976) that an applicant can amend a broad range to exclude the prior art by reference to values disclosed in the specification. The court found that if an amendment recites a range not expressly disclosed in the specification, the question of whether there is written-description support for the amendment depends on a factual inquiry into whether persons skilled in the art would consider the claimed invention to be part of the disclosed invention. Applicants should be wary of relying too much on the knowledge of one skilled in the art. The question of written-description support may be narrowly reviewed as well. For example, in In re Jones (Fed. Cir. 2001), the applicant had argued that his claim amendments, although describing embodiments not explicitly appearing in the specification, were supported because one skilled in the art would understand them to be “reasonable variations” of embodiments explicitly described. In rejecting the claims, the Federal Circuit (in a nonprecedential ruling) agreed with the Board of Patent Appeals and Interferences that “considerable speculation was required to find that a person of ordinary skill in the art would understand that the contested limitations were disclosed.” Functional language in the specification may also help if the function is achieved by a range recited in the claims. � Approximate Numerical Limitations. Applicants may improve their chance of proving infringement under the doctrine of equivalents by modifying numerical limitations with words such as “about” or “approximately.” A claim that includes “about” or “approximately” may show an intent to claim at least some subject matter near to, but outside, the recited numerical limit. Indeed, values just outside the numerical limit may even be found to literally infringe such claims. Using words of approximation in the specification can also help support the use of these terms in claim amendments. Even if words of approximation are not explicitly recited in the specification, they may still be supported if the specification as a whole shows that a high degree of precision was not intended. See Eiselstein v. Frank (Fed. Cir. 1995). But words of approximation must be consistently used in the claims as well as the specification, or any nonmodified element may be considered absolute. See Jeneric/Pentron Inc. v. Dillon Co. Inc. (Fed. Cir. 2000). � Avoid Statements Characterizing the Claimed Invention or the Prior Art. Applicants should be aware of the potential for estoppel in statements or arguments that define or characterize the claimed invention or the prior art. They should therefore exercise caution when providing details of the invention’s advantages over prior art. Prosecution history estoppel may prevent coverage under the doctrine of equivalents of infringing products that do not have exactly the same features or provide exactly the same advantages. See Hoganas AB v. Dresser Industries Inc. (Fed. Cir. 1993). In addition, using words such as “critical,” “key,” and “essential” to describe aspects of the invention may cause applicants grief when they later try to enforce a patent against an infringer who has slightly modified the invention to omit the “critical” element. See Pharmacia & Upjohn Co. v. Mylan Pharmaceuticals Inc. (Fed. Cir. 1999). Furthermore, in Vehicular Technologies Corp. v. Titan Wheel International Inc. last year, the Federal Circuit found that the accused product did not infringe because it did not meet the function of enhancing reliability that was set forth as an “objective” of the claimed invention in the “Description” section of the specification. And in Scimed Life Systems Inc. v. Advanced Cardiovascular Systems Inc. (March 14, 2001), the Federal Circuit construed a claim narrowly based, in part, on the court’s reading of the recited disadvantages of certain prior art and the recited advantages of the current invention. � Avoid Gratuitous Arguments. Applicants should be wary of arguments that are not necessary to overcome the prior art. They should make their application less scattershot and more precisely targeted, for every amendment and every argument may create prosecution history estoppel. � Do Everything but Amend. After Festo, examiner interviews, appeals, and arguments against the prima facie case of invalidity made out by the patent examiner have all taken on a heightened importance. In their efforts to avoid rejection, applicants should consider all of these nonamendment routes first. Perhaps the best way to sum up is to say again that the Federal Circuit’s decision in Festo has upped the ante on claim amendments. If there are reasonable steps that an applicant can take during patent prosecution to avoid having to amend claims, the applicant should seriously consider taking them. This article is an abridgement of course materials that the authors use in training programs for corporate patent departments.

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