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Claim Construction : Phillips vs. AWH Update
Brian P. Furrer (U.S. Patent Attorney)
As discussed a few months ago, there was an issue pending in US patent law with respect to construing terms in patent claims. Specifically, the issue was what should be the primary source for determining the meaning of terms used in the claims: (1) evidence intrinsic to the patent, such as the patent specification and prosecution history, or (2) extrinsic evidence, such as technical dictionaries and treatises.
For this reason, the Federal Court of Appeals had ordered a rehearing en banc in the case of Phillips v. AWH Corp. et al. to broadly address claim construction and resolve this issue. En banc means that all of the judges on the Federal Court of Appeals hear and consider the appeal, i.e., twelve judges, instead of the usual three judge panel that decides most appeals.
The Federal Court of Appeals published their en banc decision in Phillips v. AWH Corp. et al. on July 13, 2005. It was split decision, in which nine judges of the twelve agreed with the complete analysis of the majority opinion. Two other judges agreed with most of the majority opinion, but disagreed with respect to some points. The remaining judge wrote a dissenting opinion.
According to the majority opinion, intrinsic evidence is the primary basis for construing the terms recited in the claims of a patent. One first looks to the words of the claims themselves. Notwithstanding, the words of the claims must be read in view of the specification, which is the primary basis for construing the claims. The prosecution history also forms part of the intrinsic evidence and should be considered in construing the claims. According to the majority opinion though, the prosecution history “often lacks the clarity of the specification and thus is less useful for claim construction purposes” because the prosecution history is the record of a negotiation between the US Patent Office and the applicant.
With respect to extrinsic evidence such as dictionaries and treatises, the majority opinion observed that such evidence can be useful in claim construction and may be considered by a trial court if the trial court deems it helpful. The majority opinion further noted though, that in their view extrinsic evidence is in general less reliable than the patent and its prosecution history.
In addition, the majority opinion recognized “that the distinction between using the specification to interpret the meaning of a claim and importing limitations from the specification into the claim can be a difficult one to apply in practice.” In particular, the majority opinion noted repeated warnings in past decisions against confining claims to very specific embodiments even though such specific embodiments are described in the specification. The majority opinion further noted the Federal Court of Appeals has “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.”
At issue before the Court in the Phillips case, was the proper construction for the term “baffle” as recited in the claims. The patent specification described embodiments of the invention in which there were no baffles at right angles relative to the walls of the disclosed device. Further, there was prior art showing baffles at right angles. On this basis, the trial court and earlier appellate panel both construed the recitation of baffle in the claims as not including baffles that were at right angles to wall faces. Based on this construction, the patent owner could not prove infringement and summary judgment of noninfringement was granted and affirmed.
The majority opinion, however, did not agree. According to the majority opinion, a person of skill in the art would not interpret the disclosure and claims of the patent to mean that the term “baffle” excluded structures disposed at right angles to wall faces of the claimed device. Accordingly, the majority opinion reversed the summary judgment of noninfringement and remanded the case. On remand, it is possible that the trial court will find that claims are invalid over prior art.
The majority opinion additionally acknowledged that claims should be construed such that they are valid. Notwithstanding, the majority opinion stated that this should only be done where a claim term remains ambiguous after applying all other tools of claim construction.
From my perspective, the en banc decision is good for US patent law because it protects patent owners. Both the trial court opinion and earlier appellate opinion had a troubling construction for the term “baffle” in which it appeared that limitations from the specification were imported into the claims. The majority opinion in the en banc decision clarifies that importing limitations into the claims is improper.
In addition, the decision is useful for claim construction. It greatly clarifies the role that the intrinsic and extrinsic evidence should play in relation to one another in claim construction, and among intrinsic evidence, the relative importance of the patent specification and prosecution history.