On July 12, 2005, the U.S. Court of Appeals for the Federal Circuit issued its en banc decision in Phillips v. AWH Corp., Case Nos. 03-1269, -1286. The majority opinion, authored by Circuit Judge Bryson, (dissent by Judge Mayer) touched on most of the issues identified by the Court in its en banc order. The only en banc issue the Court expressly declined to address was whether it should accord any deference to trial court claim construction rulings. Thus, by default, the Court maintained its present practice of giving no deference to district court claim construction rulings. Indeed, it was this refusal to accord deference to the more fact-like claim construction inquiries that prompted Judges Mayer and Newman to dissent.

The determination of the proper scope of claims is the single most important issue in patent litigation. Only after the proper scope of the claims is ascertained can one proceed to determine whether the claims are infringed or invalid. Over the years, many litigants and litigators have complained claim interpretation is often unpredictable, and the recent trend toward increased reliance on dictionary definitions has not reduced unpredictability but has resulted in overbroad claim scope, oftentimes far broader than the disclosed invention. The historical unpredictability of claim construction has been evidenced by the high rate of reversal of district court claim construction rulings. Due to this high reversal rate, litigants have a tremendous incentive to appeal. Questions of infringement and invalidity are tried multiple times, resulting in the clogging of the courts and increasing litigation costs (as well as continued uncertainty).

In Phillips, the Federal Circuit provided a useful, going forward overview of claim construction protocols and canons of construction and, very significantly, has retreated from the Texas Digital "dictionary-first" approach to claim construction that has permeated many recent cases. The Phillips decision heralds a return to the intrinsic/extrinsic hierarchal evidence approach of Vitronics v. Conceptronic (1996) and the line of cases that followed. In Vitronics, the Federal Circuit set out a hierarchal framework for claim construction in which one starts with the intrinsic evidence, i.e. the claims, the specification and the prosecution history, to interpret the claims. If the meaning of the claim is clear from examining the intrinsic evidence, the inquiry is over. If the meaning is still unclear, one examines the extrinsic evidence, such as dictionaries, the prior art, the testimony of experts and in rare occasions the testimony of the inventor.

The Federal Circuit also reemphasized the importance of the specification for construing claims, citing the venerable (1967) Court of Claims case, Autogiro. The Court instructed that the specification’s role is not limited to instances where the inventor expressly defines or limits a term in the specification. Rather, it noted the specification is often the single most important claim construction tool and is more helpful than the prosecution history; the latter often being less clear as it represents an ongoing negotiation between the U.S. Patent and Trademark Office (USPTO) and the applicant.

However, the Phillips decision provides little in the way of concrete guidance on how to use the specification. For example, while conceding the fine line between using the specification to interpret the meaning of a claim and importing limitations from it is often difficult to discern, it suggested the manner in which the patentee uses a term within the specification and claims will usually make the distinction apparent. Given the very general nature of this guidance, there remains significant room for the application of various competing claim construction doctrines.

Interestingly, while the Federal Circuit stressed both that "[t]he inquiry into how a person of ordinary skill in the art understands a claim term provides an objective baseline from which to begin claim interpretation," it also warned against undue reliance upon expert testimony—particularly, testimony which is conclusory, unsupported or contradicted by the intrinsic evidence. The Court likewise noted that dictionaries, particularly technical dictionaries, are often helpful to understand how a claim term would be construed by one of skill in the art in question. However, the Court warned dictionary definitions should not be over-emphasized since dictionaries attempt to aggregate all possible definitions for particular words and applying all definitions not expressly disclaimed will result in unduly broad claims.

The Court also warned that even though there are times claims should be construed to preserve their validity, that maxim is not a "regular component of claim construction" and generally only applies when the scope of the claim is still ambiguous after applying all of the available tools of claim construction.

Fundamentally, it appears the Federal Circuit correctly abandoned the failed Texas Digital experiment and provided a helpful review of claim construction protocols in its return to the methodology articulated in its earlier en banc Vitronics decision; however, it missed an opportunity to address one of the fundamental problems that originally prompted the Court to take the Phillips case for en banc review.

Litigants can now expect that future Markman hearing will be far more focused on intrinsic claim construction evidence and far less on what had become the "battle of the dictionary definitions." It is also less likely that future Markman rulings will result in breathtakingly broad literal claim scope as compared to cases decided under the Texas Digital "dictionary first" rule.

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