Patent Claim Construction: A Sliding-Scale Standard of Review
Mullendore, Laura, The Review of Litigation
In patent suits, a determination of patent infringement consists of two steps.1 First, the court must determine the scope of the patent claims; second, it must compare the properly construed claims to die allegedly infringing device. Construction of the patent claims establishes the scope of the property rights protected by the patent; it is a fundamental principle of patent law that "the claims of a patent define the invention to which the patentee is entitled the right to exclude."3
Claims are frequently "amenable to multiple interpretations and constructions."4 Currently, patent claim construction is a pure issue of law that does not involve subsidiary or underlying questions of fact, and construction of patent claims is subject to de novo review by the court of appeals.5 However, the de novo standard of review for claim construction has been the subject of criticism, and many scholarly articles have advocated a change in the standard of review as a means of alleviating the problems currently associated with claim construction.6 The Federal Circuit, in Phillips v. AWH Corp. Phillips II), attempted to articulate a methodology to guide district courts in their interpretation of claim terms. But the approach set forth in Phillips II will not solve the problems of predictability, consistency, and efficiency that are currently associated with patent claim construction.
In November 2006, the Federal Circuit denied en banc rehearing in a claim construction case that would have enabled the court to reconsider the rule of de novo review.8 However, the numerous dissents and concurrences in the opinion indicate that at least seven of the twelve active Federal Circuit judges would be willing to revisit the issue under appropriate circumstances.9 The
bulk of scholarly literature advocating a change in the standard of review for claim construction typically endorses a standard for claim construction similar to that used for review of obviousness and enablement determinations - claim construction should be seen as a question of law reviewed de novo, and the underlying factual findings on which the determination is based should be reviewed for clear error.10
This Note asserts that the standard of review for claim construction should be potentially even more deferential - claim construction should be viewed as a mixed question of law and fact, reviewed on a sliding scale between de novo and clear error. The degree of deference given to a particular trial court's claim construction should depend on the nature of the claims, the technology itself, and the underlying factual findings. The more fact-dominated the claim construction is, the more deferential the review should be; the more law-dominated the construction is, the more independent the review should be.
This Note proceeds in three parts. Part II will give an overview of claim construction law and discuss the evolution of current claim construction jurisprudence. Part III will outline the issues and problems currently associated with claim construction. Part IV will argue that the solution proposed by the existing literature on the issue (changing the standard of review so that underlying fact findings are reviewed for clear error) will not go far enough toward alleviating the problems, and it will then outline how a sliding-scale standard of review might function.
II. THE CURRENT STATE OF CLAIM CONSTRUCTION
A. Brief Overview of Patent Law and Claim Construction Principles
A patent is a written document that describes and claims an invention, much like a land deed describes and claims a piece of property.11 The patent begins with a detailed description of the invention known as the specification.12 The specification is followed by patent claims that define the boundaries of the invention and the inventive territory that the patent purports to cover.13 In the claims, the patentee must "particularly point out and distinctly claim the part, improvement, or combination which [the patentee] claims as his invention or discovery" in order to "secure to him all to which he is entitled, [and] to apprise the public of what is still open to them. …