Baffled: Phillips v. Awh Corp. and the Reexamination of Dictionary Use in Patent Claim Interpretation

• Publication year: 2004
• Citation: Vol. 6 No. 2004

Daniel S. Matthews⁰

I. Introduction

When drafting a patent application, inventors or their legal representatives must carefully choose the language and terms employed in the claims section. A particular problem arises in a granted patent when a term with multiple definitions creates ambiguity in the interpretation of the claims and the scope of protection provided therein. How should courts determine which definition controls? Which authorities should be consulted, and if multiple authorities are consulted, how much weight should each carry respectively? These are some of the questions that the Federal Circuit seeks to address in its en banc rehearing of Phillips v. AWH Corp.¹

The outcome of Phillips will significantly affect both the drafting of future patent applications and the interpretation of all patents, including those granted prior to this case. This Recent Development reviews the basic tenets of claim construction and considers whether the Federal Circuit should continue to favor, as it has increasingly been inclined to do, a formalistic method of interpretation that focuses on how dictionaries define terms in the claim. After considering the impact an adoption of such formalism may have on patent drafting and fair competition, this Recent Development argues that the Federal Circuit should retreat from this position upon rehearing Phillips.

II. The Patent Claim: Interpretive Methodologies and Clarification of Ambiguities

A. Roles of Judge and Jury in the Enforcement of Patent Rights

When an inventive entity, whether an individual, a group of individuals, or a corporation, seeks to enforce its patent rights against an alleged infringer, it must show that the allegedly infringing product or process is covered by the claims section of the inventor's patent.² To determine whether the product infringes the patent, the patent holder must interpret the claims section of the patent and decide whether the other party's product actually infringes the patent as construed.³ In Markman v. Westview Instruments, Inc., the United States Supreme Court held that claim construction is an issue of law to be decided by judges, while infringement is an issue of fact to be determined by a jury.⁴ As a result of this case, pre-trial hearings, commonly referred to as Markman hearings, are now held outside the presence of the jury to resolve interpretive ambiguities in a patent claim.

B. Written Description Requirement

Under federal patent law, a patent's "specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains . . . to make and use the same [invention]."⁵ In order to meet this requirement, the inventor must "describ[e] the invention, with all its claimed limitations."⁶ This means that the claims must be supported by the written description in the specification, and the claims may have no more breadth than what is described in the specification.⁷ Because the claims must be read in light of the specification,⁸ it is imperative that a patent drafter describe the invention with clarity in the specification.⁹

C. Sources of Evidence in Claim Construction

Two commonly used sources of evidence in claim construction are the claims themselves and the specification. According to the Federal Circuit, terms within a claim "are generally given their ordinary and customary meaning, [but] a patentee may choose to be his own lexicographer and use terms in a manner other than their ordinary meaning, as long as the special definition of the term is clearly stated in the patent specification or file history."¹⁰ As a result, "it is always necessary to review the specification to determine whether the inventor has used any terms in a manner inconsistent with their ordinary meaning. The specification acts as a dictionary when it expressly defines terms used in the claims or when it defines terms by implication."¹¹ The Federal Circuit has further asserted that, "[u]sually, [the specification] is dispositive; it is the single best guide to the meaning of a disputed term."¹²

These sources—the specification and the claims—along with the prosecution history¹³ are considered intrinsic evidence that may be consulted when construing claim language.¹⁴ Aside from the intrinsic evidence, courts may also consult extrinsic evidence.¹⁵ Extrinsic evidence may include expert testimony, inventor testimony, dictionaries, encyclopedias, and treatises.¹⁶

D. Role of Dictionaries, Encyclopedias, and Treatises

Although dictionaries¹⁷ have been considered valid sources of evidence in patent cases dating as far back as the 1940s,¹⁸ their validity as extrinsic evidence was affirmed in multiple cases in the mid-1990s, around the time of the Markman decision.¹⁹ Nevertheless, dictionaries were not considered a primary source of evidence until the Federal Circuit decided Texas Digital Systems, Inc. v. Telegenix, Inc.²⁰ in 2002. In Telegenix, the Federal Circuit asserted that "[c]onsulting the written description and prosecution history as a threshold step in the claim construction process, before any effort is made to discern the ordinary and customary meanings attributed to the words themselves, invites a violation of our precedent counseling against importing limitations into the claims."²¹ The court further stated:

By examining relevant dictionaries, encyclopedias and treatises to ascertain possible meanings that would have been attributed to the words of the claims by those skilled in the art, and by further utilizing the intrinsic record to select from those possible meanings the one or ones most consistent with the use of the words by the inventor, the full breadth of the limitations intended by the inventor will be more accurately determined and the improper importation of unintended limitations from the written description into the claims will be more easily avoided.²²

This decision was seen as a significant move toward formalism in claim construction.²³

The Telegenix court held that the intrinsic record must be examined, but only to ensure that the "ordinary and customary meaning" is not rebutted or, if there are multiple definitions, to determine which was intended.²⁴ The court's decision established dictionaries as the initial source of evidence in patent claim construction. This holding appears irreconcilable with the past holdings of the Court. The Federal Circuit had previously held that the intrinsic evidence should be examined first, and if any ambiguities in claim construction remain, sources of extrinsic evidence may be consulted.²⁵ In Telegenix, however, the court stated dictionaries are outside the classification of extrinsic evidence.²⁶ This appears to be an attempt to avoid reversing its past holdings.²⁷ The Federal Circuit backed away from treating dictionaries as extrinsic evidence, as it had in Markman, by placing them in their own category.²⁸

E. Phillips v. AWH Corp.

Recently the Federal Circuit chose to reexamine the trend toward a formalistic approach to claim construction.²⁹ In Phillips v. AWH Corp.,³⁰ the plaintiff patented a design for modular wall panels that could be used in correctional facilities because of their "desirable sound and fire resistance, impact resistance (i.e., against bullets, bombs), and axial and lateral load bearing qualities."³¹ In Phillips, the Federal Circuit largely focused on the definition of the term "baffle" as used in the patent claims. The alleged infringer "assert[ed] that the key innovative feature of the invention [was] the baffle configuration, including both the angled orientation and the interlocking pattern limitations."³² If the baffles constituted the key innovative feature, then infringement would most likely be precluded if the allegedly infringing product did not have baffles as construed in the patent.

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