Fence posts or sign posts? Rethinking patent claim construction.

Author:Burk, Dan L.

INTRODUCTION I. THE BREAKDOWN OF PERIPHERAL CLAIMING A. The Process of Claim Construction B Disputes over the Meaning of Patent Claims C. The Costs of Claim Construction II. CENTRAL CLAIMING A. From Sign Posts to Fence Posts B. The Continuing Presence of Central Claiming C. Rules and Standards in Claim Construction III. IMPLEMENTING CENTRAL CLAIMING A. How Central Claiming Might Work in the United States 1. Do We Need Patent Claims at All? 2. Central Claims in the PTO 3. Central Claiming in Litigation B. Considering Objections to Central Claiming C. Half-Steps: Ending the Hegemony of Markman CONCLUSION INTRODUCTION

Patents are, in theory, a legal right to exclude competitors from using the patentee's invention. Exactly what the patentee gets to prevent others from using depends, however, on how the law defines the scope of the patent right. In modern American patent doctrine, we define what the patentee owns not by what she actually built or disclosed, but by what she claimed. Courts and commentators regularly analogize patent claims as akin to the "metes and bounds" of a real property deed, (1) defining the outer boundaries of a "property" right conferred on the patentee. (2) According to this view, known as the peripheral claiming approach, words of a claim form a sort of conceptual "fence" that marks the edge of the patentee's rights. And for the last dozen years, judges have had the responsibility of defining that periphery, interpreting the perimeter of patent claims in a pretrial proceeding known as a Markman hearing. (3)

It isn't working. Despite repeated efforts to set out the rules for construing patent claims, culminating in the Federal Circuit's en banc Phillips decision in 2005, (4) parties and courts seem unable to agree on what particular patent claims mean. Patent law has provided none of the certainty associated with the definition of boundaries in real property law. Literally every case involves a fight over the meaning of multiple terms, and not just the complex technical ones. Recent Federal Circuit cases have had to decide plausible disagreements over the meanings of the words "a," (5) "or," (6) "to," (7) "including," (8) and "through," (9) to name but a few. Claim construction is sufficiently uncertain that many parties don't settle a case until after the court has construed the claims, because there is no baseline for agreement on what the patent might possibly cover. Even after claim construction, the meaning of the claims remains uncertain, not only because of the very real prospect of reversal on appeal but also because lawyers immediately begin fighting about the meaning of the words used to construe the words of the claims.

The problem is not just lack of understanding. Rather, claim construction may be inherently indeterminate: it may simply be impossible to cleanly map words to things. (10) Patent attorneys seize on such indeterminacy to excuse infringement or to expand their client's exclusive rights. The Federal Circuit reworks patent claims that have already been construed by district court judges, and the patent system increasingly revolves around the definition of terminology rather than the substance of what the patentee invented and how significant that invention really is. The key feature of peripheral claiming, setting out clear boundaries to warn the public of what is and is not claimed--the "notice function" of patents that has received so much attention in re cent years (11)--increasingly seems to be an illusion. (12) And it is a dangerous illusion, because it means that courts define the scope of legal rights not by reference to the invention but by reference to semantic debates over the meaning of words chosen by lawyers.

If patent-claim terms lack the virtue of certainty and are in fact doing mischief in the patent system, perhaps we should begin to rethink the whole enterprise of peripheral claiming and the process of claim construction that accompanies it.

There is an alternative. Before 1870, the scope of U.S. patents was determined using a system of "central claiming." Under a central-claiming approach, the patentee does not delineate the outer reach of what it claims. Rather, the patentee discloses the central features of the invention--what distinguishes it from the prior art--and the courts determine how much protection the patent is entitled to by looking at the prior art that cabins the invention, how important the patentee's invention was, (13) and how different the accused device is. In some countries elements of that system remain to this day, (14) and indeed there are vestiges of central claiming in the U.S. patent system. (15) Central claiming is also the norm in U.S. copyright, trademark, and trade secret law.

If the goal of peripheral claiming was to establish fence posts marking the boundary of the patent, we can think of central claiming as replacing fence posts with sign posts identifying new inventions. (16) Whereas peripheral claiming purports to mark the outermost boundary of the patentee's claims, central claiming describes the core or gist of the patentee's contribution to technology. In this Article, we argue that the way for the patent system to move ahead may be by looking behind. Rather than relying on the illusion of peripheral fence posts, patent law may do better to once again look to central sign posts.

Central claiming would be a radical change, and perhaps the country is not ready to take such a step. Indeed, we are not ourselves fully persuaded that the benefits of central claiming outweigh the costs. But it is useful as a thought experiment, bringing our attention back to the patentee's invention rather than words written by lawyers. Once we are willing to look beyond a pure peripheral-claiming system, there are a number of smaller steps that courts could take to dethrone the Markman hearing from its position of honor in patent litigation. To begin, not every term in a patent claim needs to be construed or fought over. We might reasonably limit claim construction to the explanation of technical terms that a jury is not likely to understand, restoring the original purpose of claim construction. We might also limit claim construction to the point of novelty of the invention, to prevent drafting ambiguities on collateral issues from rendering a patent worthless. Second, we could pay more attention to the patentee's actual description of the invention and less to the words of the claims themselves in deciding the patent's importance and coverage, thus avoiding abuse of the litigation process by patentees who invent one thing and later claim to own something else entirely. Third, we could reinvigorate the doctrine of pioneer patents, restoring some vitality to the doctrine of equivalents--which Markman killed (17)--in the subset of cases in which the defendant's product in fact captures the principle of the invention. Finally, we could make peripheral claims industry-specific, allowing patentees in industries like chemistry who believe they can effectively define a genus to do so, but not limiting patentees in less certain areas to the vagaries of patent-claim language. (18)

We begin in Part I by examining in some detail the sorry state of peripheral claiming, and in particular the failure of patent claims to specify the scope of the rights granted to patentees. The picture we paint will be familiar to anyone who is regularly engaged with the modern U.S. patent system. We then review the features of central claiming in Part II, including the development of claims themselves, tracing the rise and decline of a system that was replaced, ironically, as lacking the certainty that peripheral claiming was thought to provide. In Part III, we discuss the benefits that might be recaptured by a move back toward central claiming as well as the costs of such a move. We also examine several hybrid measures that might be adopted, either in the process of moving from fence-posting to sign-posting or as improvements over the current system that still stop short of fully adopting central claiming.


    The idea behind peripheral claiming, which U.S. patent law adopted in the 1870s, was to establish the "metes and bounds" of the invention in a manner analogous to real property deeds. But any analogy between patent boundaries and real property boundaries is no more than an analogy, and a flawed analogy at that. (19) Those who are intimate with the patent system have long understood that it is simply impossible to define boundaries of invention with the physical or descriptive precision of defining the boundaries of real property. (20) Even the boundaries of real property can shift, as when a boundary river shifts its course. But boundaries based upon language lack the social durability of surveying data or GPS coordinates--the stable, agreed-upon criteria for positioning boundaries in space. (21) This combination--semantic "boundaries" coupled with a metaphor that assumes definition and stability--has led to a situation in which the metaphorical virtues of peripheral claiming obscure the actual damage it is doing to innovation.

    1. The Process of Claim Construction

      The peripheral-claiming system seeks to define the outer boundaries of the invention. In theory, the process works as follows: The applicant and the PTO examiner negotiate over the scope of the invention, limiting it in view of the prior art and the range of examples that the applicant has enabled. The resulting claims define the scope of the patent. Competitors can then read the patent claims and know whether their actions will infringe the patent, and therefore whether they need to avoid the patent or take a license. If they decide to infringe, the patentee sues, and courts determine validity and infringement by comparing those claims to the prior art or the defendant's product, respectively.

      Every stage of this theoretical story depends...

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