To Construe or Not to Construe: At the Interface between Claim Construction and Infringement in Patent Cases

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I. INTRODUCTION

The United States Court of Appeals for the Federal Circuit is approaching its thirtieth anniversary (1) as the key driving force behind development of patent law in the United States. (2) As a single, specialized appellate court, the Federal Circuit has exclusive jurisdiction to hear patent appeals from U.S. district courts and the International Trade Commission. (3) Its ability to adapt modern patent jurisprudence to address the evolving concerns of the patent law community and the needs of the patent system is unique and powerful. (4) A frequently exercised and somewhat controversial power of the Federal Circuit is its ability to perform de novo review of trial court determinations of claim construction, which assigns a legal scope to patent claims as a matter of law. (5) Claim construction is perhaps the most critical issue in patent disputes and commentators frequently identify it as a key factor underlying high reversal rates and uncertainty in patent law. (6)

This fundamental issue in how our courts resolve patent disputes involves a difficult line-drawing exercise between two steps: First, the court must construe the legal scope of patent claims as a matter of law, and, second, the fact finder must apply the construed claims to the accused instrumentality to determine infringement as a question of fact. (7) The Federal Circuit recognized this theoretical construct early in its jurisprudence (8) and subsequently said it "requires two separate steps." (9) Further, the Markman v. Westview Instruments, Inc. and Cybor Corp. v. FAS Technologies, Inc. opinions have "invigorated" (10) and "amplified" the first step, claim construction, as a threshold legal inquiry to be performed exclusively by the court prior to addressing the question of infringement. (11) As a consequence, drawing the line between these two inquiries, which occurs in every patent dispute, usually has the effect of determining whether a judge, as a matter of law, or a jury, as a matter of fact, resolves the question of infringement. (12) This line, however, is often difficult to draw and is subject to potential strategic maneuvering. Because of the difficulty in drawing this line, the Federal Circuit's precedents often seem to provide inconsistent guidance on how far the judge's duty to construe claims extends and where the fact finder's role in determining infringement begins. (13) As a result, courts and litigants have substantial leeway in defining the law-fact divide and, perhaps, the judge-jury allocation in individual cases.

This Article conceptualizes the imaginary "line" or "boundary" that lies at the interface between the legal inquiry of claim construction and the separate, factual inquiry of infringement by analyzing it in two key respects: "procedural" and "substantive." The line exists procedurally as the proximity in time between the act of construing claim scope and the act of applying that claim scope to the accused instrumentality. The line exists substantively in the extent to which claim construction is used to define the boundaries and contours of claim scope in a manner that readily maps to an accused product versus the extent to which "unconstrued" plain claim language is simply compared to the accused product. Whether considered in the procedural or substantive context, the law has difficulty drawing precise boundaries between claim construction and infringement, which are, in theory, separate inquiries of fact and law. As a result, in practice, this boundary may perhaps more appropriately be understood as existing on a continuum, rather than as a line.

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This Article examines the blurring of this interface in both the "procedural" and "substantive" contexts. Part I discusses the background and modern legal framework for classifying claim construction as a pure question of law that is answered prior to and separate from the issue of infringement. Part II analyzes the claim construction-infringement boundary in a procedural context by examining the stages of a case at which these inquiries are typically performed and the degree to which courts construe claims "in a vacuum," without reference to the accused product. …