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On July 12, the U.S. Court of Appeals for the Federal Circuit issued its long-awaited en banc ruling in Phillips v. AWH Corp., 2005 WL 1620331. At issue was the proper methodology for interpreting patents. Leading up to Phillips, a tension had developed among several different lines of cases standing for competing propositions, including the extent to which extrinsic sources of evidence such as dictionaries should be used to construe a patent phrase before consulting the patent itself. This decision was closely watched by all members of the patent bar. In fact, 36 amicus briefs were filed in this case. Specifically at issue was the meaning of the word “baffles,” and whether the claim in the patent should be limited to baffles placed at angles other than 90 degrees because this was the only embodiment clearly described in the patent, despite the fact that nothing in the patent claim said that a particular angle of the baffle was required. The district court interpreted “baffles” unfavorably to Edward H. Phillips’ claim for infringement, finding it was limited to angles other than 90 degrees. Phillips v. AWH Corp., No. 97-N-212 (D. Colo. Jan. 21, 2003). On appeal, a divided panel initially affirmed the district court’s holding of noninfringement, but on different grounds. Phillips v. AWH Corp., 363 F.3d 1207 (Fed. Cir. 2004). Even though the claim of the patent was silent as to whether a particular angle of placement was needed for the baffles, the majority focused on the detailed description of the patent, which repeatedly mentioned baffles at angles other than 90 degrees and referenced a benefit of placing them at an angle other than 90 degrees, and gave the term “baffles” a restrictive meaning. Id. at 1212-13. The dissent, on the other hand, urged that the meaning of the term “baffles” should have been derived from general purpose dictionaries. Id. at 1218. Within four months of this initial panel decision in Phillips, 11 of 12 judges of the Federal Circuit decided to vacate the panel decision and to solicit the bar to submit briefs concerning the basic principles concerning how a patent’s claims are interpreted. Phillips v. AWH Corp., 376 F.3d 1382 (Fed. Cir. 2004) (en banc) (per curiam order). Although the order identified seven issues, the major focus of the recent Phillips opinion concerned the interplay between the role of the patent’s specification and the roles of dictionaries and similar sources to interpret a claim term. The majority reversed the prior panel decision and found that the claim did cover baffles at other than 90 degrees, delivering a victory to the patent owner. Every patent contains a detailed description of an invention known as the specification, which is often a place where the drafter defines terms used in the claims of the patent. At the heart of the Phillips decision was the majority’s reaffirmance that the specification must be consulted to construe the meaning of a claim if there is doubt, and that the specification trumps “extrinsic” sources of claim interpretation such as dictionaries. While this may sound logical, some prior rulings by the Federal Circuit had suggested that dictionaries had greater importance than the patent specification for interpreting claims. As the court observed in C.R. Bard Inc. v. U.S. Surgical Corp., 388 F.3d 858, 861-63 (2004): “Language in some of our recent cases, however, suggests that the intrinsic record, except for the claims, should be consulted only after the ordinary and customary meaning of claim terms to persons skilled in the pertinent art is determined. … The language in these cases emphasizes technical and general-usage dictionaries in determining the ordinary meaning. … Under this approach, where the ordinary meaning of a claim term is thus evident, the inventor’s written description of the invention, for example, is relevant and controlling insofar as it provides clear lexicography or disavowal of the ordinary meaning.” The Phillips majority observed that “[t]he main problem with [prior rulings] elevating the dictionary to such prominence is that it focuses the inquiry on the abstract meaning of words rather than on the meaning of claim terms within the context of the patent.” 2005 WL 1620331, at 14. Rather than overrule these prior cases, the Phillips majority reconciled them by approving of the continued use of dictionaries in a subservient role to consulting the specification of the patent, specifically noting that such review of dictionaries as an extrinsic resource can help “avoid the danger of reading limitations from the specification into the claim.” Id. at 15. When it comes to consulting dictionaries, the Phillips majority offered this guidance to district courts: “In sum, extrinsic evidence may be useful to the court, but it is unlikely to result in a reliable interpretation of patent claim scope unless considered in the context of the intrinsic evidence. Nonetheless, because extrinsic evidence can help educate the court regarding the field of the invention and can help the court determine what a person of ordinary skill in the art would understand claim terms to mean, it is permissible for the district court in its sound discretion to admit and use such evidence. In exercising that discretion, and in weighing all the evidence bearing on claim construction, the court should keep in mind the flaws inherent in each type of evidence and assess that evidence accordingly.” Id. at 10. RISKS IN USING EXTRINSIC EVIDENCE The Phillips majority took the opportunity of this en banc ruling to expound on the reasons why intrinsic evidence (such as the patent specification and file history) is better than extrinsic evidence (such as dictionaries and expert witnesses) for interpreting patents: “We have viewed extrinsic evidence in general as less reliable than the patent and its prosecution history in determining how to read claim terms, for several reasons. First, extrinsic evidence by definition is not part of the patent and does not have the specification’s virtue of being created at the time of patent prosecution for the purpose of explaining the patent’s scope and meaning. Second, while claims are construed as they would be understood by a hypothetical person of skill in the art, extrinsic publications may not be written by or for skilled artisans and therefore may not reflect the understanding of a skilled artisan in the field of the patent. “Third, extrinsic evidence consisting of expert reports and testimony is generated at the time of and for the purpose of litigation and thus can suffer from bias that is not present in intrinsic evidence. The effect of that bias can be exacerbated if the expert is not one of skill in the relevant art or if the expert’s opinion is offered in a form that is not subject to cross-examination. … “Fourth, there is a virtually unbounded universe of potential extrinsic evidence of some marginal relevance that could be brought to bear on any claim construction question. In the course of litigation, each party will naturally choose the pieces of extrinsic evidence most favorable to its cause, leaving the court with the considerable task of filtering the useful extrinsic evidence from the fluff. … “Finally, undue reliance on extrinsic evidence poses the risk that it will be used to change the meaning of claims in derogation of the ‘indisputable public records consisting of the claims, the specification and the prosecution history,’ thereby undermining the public notice function of patents.” Phillips, 2005 WL 1620331, at 11. Although prior cases had firmly established the subservience of extrinsic evidence in general, dictionaries in particular had begun to creep into a more prominent position in some decisions, prompting the Phillips court once again to reiterate this precedent. Being able to find the one dictionary out of hundreds of available dictionaries that defines a disputed patent term in favor of one’s client had become a favorite pastime of patent litigators, a fact not lost on the Phillips court. In noting this danger of dictionary shopping, the Phillips court warned that claim meaning should not rise and fall on the preferences of one dictionary editor over another. Id. at 15. THE STRUGGLE CONTINUES In again elevating the specification to a position of prominence in claim interpretation, however, the court had to deal with another difficult area: the line between what constitutes an impermissible narrowing of a claim caused by importing an extraneous limitation from the specification into the claim, and what represents permissible interpretation of a word in the claim based on statements found in the specification. As to the patent-in-suit in Phillips, the majority found that the specification illustrated baffles at other than 90 degrees as only one embodiment. Thus, limiting the claim to that one embodiment (as did the initial decisions) represented an impermissible importation of an extraneous limitation. The court suggested that walking this line is not an impossible task: “[T]he line between construing terms and importing limitations can be discerned with reasonable certainty and predictability if the court’s focus remains on understanding how a person of ordinary skill in the art would understand the claim terms. For instance, although the specification often describes very specific embodiments of the invention, we have repeatedly warned against confining the claims to those embodiments. … In particular, we have expressly rejected the contention that if a patent describes only a single embodiment, the claims of the patent must be construed as being limited to that embodiment.” Id. at 15. While this stern warning against importation of extraneous limitations might give patent owners a reason to cheer, it offers little practical guidance to judges who must make this determination every time a patent is construed. When looking at the underlying facts of the Phillips patent, there is a strong realization that the Phillips decision places a premium on quality patent draftsmanship. If Phillips had only stated in the specification that the baffles were “optionally” placed at angles other than 90 degrees, then the case might have ended in Phillips’ favor long ago. The use of such a phrase would have made it clear that angles other than 90 degrees were optional and represented only one embodiment. The use of phrases such as “optionally” or “in one embodiment” in front of nonessential limiting phrases in the specification could not be more important in light of Phillips. Pressure in some sectors to draft patents more efficiently, in less time and at lower cost will only increase the number of disputes relating to patent interpretation. There will continue to be cases like Phillips where the line will be hard to draw, although at least now the courts know that the patent specification trumps the dictionary. Stephen B. Maebius and Harold C. Wegner are partners, and Sean A. Passino is an associate, in the Washington office of Foley & Lardner. Wegner is a professor at George Washington University Law School.

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