After-Arising Technologies and Tailoring Patent Scope

52 Pages Posted: 9 Nov 2004 Last revised: 6 Apr 2009


The patent law doctrine that allows patentees to gain exclusivity beyond what they literally claim in their patent - termed the doctrine of equivalents - has received a significant amount of attention as of late from both courts and scholars. Of particular emphasis in this recent focus on the doctrine of equivalents is the ability for patentees to gain exclusivity over equivalent after-arising technologies - technologies that develop after the patent's filing date.

With this recent emphasis has come questions regarding the propriety of after-arising equivalents protection in patent law. The debate focuses on two main questions. First, whether the doctrine of equivalents is needed in order to actually exclude those who use after-arising technologies to practice the invention. Some contend that a patent claim drafter cannot anticipate and account for later developed substitutes for a claim element, and therefore the doctrine of equivalents is needed. Others suggest that the literal scope of the patent's claims - the traditional metric of the patent's scope of exclusivity - can provide the patentee with protection against later developed technologies. Second, even if the doctrine is the only mechanism through which the patentee can gain protection for after-arising equivalents, questions still arise as to whether the patent system should provide such protection. Allowing the patentee to exclude the use of technology developed after her invention can be seen as giving the patentee too much protection and providing a disincentive for subsequent inventions. On the other hand, after-arising equivalents protection may be crucial to providing the patentee with adequate patent protection and maintaining the incentive to invent.

This Article takes a critical look at after-arising equivalents protection and concludes that such protection is needed to capture after-arising technologies but should be tailored to rapidly developing cumulative technology industries. In particular, tailoring protection in such way maintains the incentive to invent by giving the potential inventor some assurance that she can maintain her market position long enough to recoup her research and development costs. Furthermore, by focusing protection on rapidly developing industries, the deterrent effects on follow-on inventions are minimized and a self-correcting mechanism is introduced.

Keywords: Patents, claims, claim scope, equivalents, doctrine of equivalents, after-arising technologies, later developed technology, tailoring, invention, innovation, technology

JEL Classification: K39, K40, K41, O31, O33, O34, O38

Suggested Citation

Cotropia, Christopher Anthony, After-Arising Technologies and Tailoring Patent Scope. NYU Annual Survey of American Law, Vol. 61, 2005, Tulane Public Law Research Paper No. 04-10, Available at SSRN:

Christopher Anthony Cotropia (Contact Author)

University of Richmond - School of Law ( email )

28 Westhampton Way
Richmond, VA 23173
United States

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