This Article explores the claiming systems of patent and copyright law. It first develops a two-dimensional taxonomy: claiming can be either peripheral or central and either by characteristic or by exemplar. Patent law has principally adopted a system of peripheral claiming, requiring patentees to articulate by the time of the patent grant their invention's bounds, usually by listing its necessary and sufficient characteristics. Peripheral claims in patent law are conventionally thought to give notice to the public of the extent of the set of protected embodiments so as to encourage efficient investment in innovation, thereby fostering patent law's overarching goal of stimulating useful innovation. And copyright law has implicitly adopted a system of central claiming by exemplar, requiring the articulation only of a prototypical member of the set of protected works - namely, the copyrightable work itself fixed in a tangible form. Copyright protection then extends beyond the exemplar to substantially similar works, a set of works to be enumerated only down the road in case-by-case infringement litigation. Despite patent law's typical peripheral claims by characteristic and copyright law's typical central claims by exemplar, in practice, patent and copyright claiming are each heterogeneous. Patent law retains some vestiges of the central claiming under which it used to operate, through the doctrine of equivalents, statutory means-plus-function claiming, and dependent claims. And patent law encourages some claiming by exemplar through its best-mode requirement and Markush claims. By contrast, copyright law, through the approved use of licenses to permit others to make substantially similar works, encourages expression of the bounds of works permissibly created under such licenses and the delineation of characteristic features of the set of protected works and. These expressions in legally binding contracts bring forms of peripheral claiming and claiming by characteristic into copyright law. This Article explores which forms of claiming promote intellectual property's overarching constitutional goal, "To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries." It considers how each sort of claiming affects the costs of drafting claims, efficacy of notice to the public of the set of protected embodiments, ascertainment of protectability, breadth of the set of protected works, and the protectability of works grounded in after-developed technologies. That the choice of claiming systems implicates the foregoing factors - factors essential to calibrating intellectual-property law to stimulate innovation - in different ways underscores the importance of choosing a claiming system with care. Though patent law admirably incorporates all four types of claiming flexibly, its typical peripheral claims by characteristic do not provide sufficient public notice of the set of protected embodiments, which negatively affects assessments of protectability and the operational breadth of the set of protected works. I suggest that patent law can be tweaked to stimulate innovation by adding claiming elements more reminiscent of copyright law, namely central claims and claims by exemplar. Claiming in copyright law is more complicated. As it stands, copyright's central claims by exemplar provide little notice to the public, leading risk-averse third parties either to take licenses even as to works not protected by copyright or avoid them completely, a situation that grants too heavy a copyright reward at the expense of generating further creativity. From that vantage point, it would seem far more productive to require - or at least provide significant incentive to - copyright claimants ex ante to claim their works centrally by characteristic. Such claims would seem to provide significantly better ex ante notice in two ways. First, they would give a good indication as to those works that would be considered to be substantially similar to the created work and thus protected under the copyright by allowing feature-by-feature comparisons. Second, they would help explicate which substantially similar works would nonetheless be permissible uses under the doctrine of fair use, by encouraging straightforward determinations of works that borrow from the copyrighted work in ways that do not implicate too many of the claimed features or transform it significantly. But aspects integral to the copyright system-including its fine line between protecting expression but not ideas, grounded in the First Amendment; societal views on describing the artistic works copyright protects; and the ease of creating copyrightable works-give significant pause to any notion of adopting central claiming by characteristic in copyright
