Forcing patent claims.

• Author: Chiang, Tun-Jen

An enormous literature has criticized patent claims for being ambiguous. In this Article, I explain that this literature misunderstands the real problem: the fundamental concern is not that patent claims are ambiguous but that they are drafted by patentees with self-serving incentives to write claims in an overbroad manner. No one has asked why the patent system gives self-interested patentees the leading role in delineating the scope of their own patents.

This Article makes two contributions to the literature. First, it explicitly frames the problem with patent claims as one of patentee self-interest rather than the intrinsic ambiguity of claim language. Second, it provides a counterintuitive answer to the question of why the patent system relies on patentee-drafted claims. Although giving patentees claim-drafting power undoubtedly leads to overbroad patent rights, such an allocation of drafting power is nonetheless socially efficient. This is because the Patent and Trademark Office ("PTO") and the courts lack the information necessary to determine the correct scope of a patent in the first instance. Requiring patentees to write claims forces them to take a position, a process that discloses some of the patentee's private information and reduces the complexity of subsequent decisionmaking by courts and the PTO. While patentees will overclaim, they cannot overclaim too much, and relying on an imperfect claim is better than having a court or the PTO make an uninformed guess in the first instance. The Article concludes by explaining the implications of this insight for the debate over claim construction.

TABLE OF CONTENTS INTRODUCTION I. THE PUZZLE OF PATENTEE-DRAFTED CLAIMS A. Background on the Patent Document 1. The Specification Describes an Embodiment 2. The Claim Delineates Monopoly Scope B. Patentee Drafting and the Self-Interest Problem C. The Claim-Ambiguity Literature as an Implicit Critique 1. Dan Burk and Mark Lemley 2. Oskar Liivak 3. Chris Cotropia 4. Peter Lee 5. Robert Merges and John Duffy 6. Judge S. Jay Plager II. THE INFORMATION-FORCING FUNCTION OF CLAIMS A. An Analogy: The Value of Contracts of Adhesion B. Courts Lack Information About the Real Invention 1. The Misconception of the Invention as an Embodiment 2. The Problem of Identifying the Inventive Idea 3. The Impossibility of Direct Determination C. Claims Force Information from Patentees D. The Imperfection of Claims and Ex Post Adjustment III. IMPLICATIONS FOR THE CLAIM-CONSTRUCTION DEBATE A. Short-Term Efficiency: Equal Weight to All Evidence B. Long-Term Incentives: More Weight to Claim Text C. Balancing Long-Term and Short-Term Efficiency IV. ADDRESSING OBJECTIONS A. The Linguistic Indeterminacy Thesis B. Claim Amendments and Multiple Claims CONCLUSION INTRODUCTION

One of the oddest features of the patent system is that patentees get to draft the patent "claim." (1) Because the patent claim defines the scope of the monopoly, (2) patentees have a strong incentive to subtly slant the claim's language in a way that aggrandizes their rights to the detriment of the public. Moreover, it is impossible for the Patent and Trademark Office ("PTO") to police patentees so fully as to detect every subtle drafting trick. (3) In short, it would seem a good idea to prohibit patentees from drafting claims and instead give claim-drafting power to a neutral entity such as the PTO or a court.

Much of the literature on patent-claim construction can be understood as implicitly criticizing the allocation of drafting power to patentees, although no one has done so explicitly. (4) The existing literature on claim construction focuses on what I call the linguistic indeterminacy thesis--the argument that the problem with patent claims is their linguistic ambiguity and that such ambiguity results in overbroad patent rights. (5) But as I have explained in a prior article with Lawrence Solum, (6) patent claims are not especially ambiguous, and, in any case, ambiguous claims would not obviously lead to systematically overbroad patent rights since ambiguity can be construed either broadly or narrowly. Properly understood, the critics' real concern is not that claims are ambiguous but that self-serving patentees draft the claims in an overbroad manner. (7) In other words, the critics implicitly argue that patentee-drafted claims are nothing more than self-serving statements entitled to no weight. Viewed in this light, the question becomes the following: Why does the patent system require patentees to draft claims? And what is the social value of patentee-drafted claims?

This Article provides an answer: patentee-drafted claims are socially valuable because they force patentees to disclose an imperfect approximation of the correct scope of a patent. (8) Although patentees will overclaim, they cannot overclaim too much, (9) and some degree of overbreadth is tolerable compared to the alternative. Namely, the only obvious alternative to relying on patentee-written claims is for some governmental entity, such as the PTO or a court, to determine the correct scope of a patent in the first instance. And a central premise of having a patent system at all (rather than some alternative incentive mechanism such as a government-sponsored prize system) is that the government lacks sufficient information to determine the correct level of reward for particular innovations. (10) In other words, the only alternative to relying on somewhat overbroad patentee-drafted claims is for judges to hazard almost completely arbitrary guesses about optimal patent scope. (11)

This insight has important implications for the long-running debate over claim construction. Many commentators argue that, because claim text often does not describe the real invention, courts should use their interpretative powers to overcome this defect. (12) In its extreme form, the argument holds that courts should abolish claims altogether and look only at external evidence (i.e., evidence outside the claim, such as the patent specification or expert testimony) to determine the real invention. (13) In a less extreme form, the argument is that, although courts need not abolish claims, they nonetheless should give external evidence greater weight in the interpretative calculus in order to compensate for the patentee's drafting bias and to obtain the most accurate determination of the real invention. (14) As this Article will explain, both of these arguments turn the problem on its head: the critics implicitly assume that courts can reliably discern the real invention (i.e., the optimal patent scope) (15) without claims, but the whole reason that claims are required is that courts lack the capacity to perform this function.

The information-forcing insight's initial implication is that courts should refrain from abolishing claims altogether and from attempting directly to discern optimal patent scope; such a methodology faces the problem of insurmountable information costs. But the information-forcing insight has another implication: if courts did not give patentee-written claim text any more weight in claim construction than other types of evidence, then patentees would have no incentive to spend money to draft claims. (16) The long-term result would be de facto abolition, which would once again increase judicial information costs.

The result of this analysis is that courts must delicately balance two competing considerations. In the short run, giving weight to both claim text and external evidence will generate the best outcomes, as courts can reap the information benefits of claim text while also using external evidence to detect and rectify a particular patentee's drafting bias. In the long run, however, courts cannot rely too heavily on external evidence, because a patentee's incentive to write claims, and to write them in an informative manner, would disappear if courts gave claim text too little weight. As a result, courts must balance the short-term desire to achieve better outcomes (the equal-weight approach) against the long-term need to preserve incentives for patentee claim drafting (the more-weight-to-claim-text approach). And such a balancing act reflects real life, where courts give primary weight to claim text--by treating the written claim as a presumptive baseline for patent scope--but also do not exclude external evidence from the analysis completely. (17) This Article therefore provides a normative and descriptive theory for how courts should and do construe patent claims.

The Article proceeds in four Parts. Part I provides a background and describes the puzzle of allowing patentees to write patent claims, as well as explains the adverse consequences (and implicit criticisms) that allocating drafting responsibility in this way has produced. Part II then explains why allocating drafting responsibility to patentees is an efficient mechanism to solve an underlying information problem. Part III elaborates on a key implication of the theory--i.e., that in order to provide an incentive for patentees to draft claims and to convey accurate information, courts must give claim text some weight over external evidence, a position that contradicts many academic proposals. Part IV then addresses some objections, and a brief conclusion follows.

1. THE PUZZLE OF PATENTEE-DRAFTED CLAIMS

   1. Background on the Patent Document

      A U.S. patent is a complex document, but its two most important parts are the specification and the claims. (18) The patentee drafts both the specification and the claims, and both are supposed to describe the patentee's invention. (19) Although the Patent Act uses the word "invention" in both of these contexts, the term refers to two distinct concepts. As this Section will explain, the specification describes an invention in the sense of an embodiment, while the claim describes an invention in the sense of monopoly scope.

      1. The Specification Describes an Embodiment

         In simplified terms...