ABSTRACT
This Essay examines a fundamental asymmetry in patent law: while patentability is evaluated at the patent application’s filing date, infringement is evaluated at the time of infringement. This temporal misalignment allows patentees to paradoxically enforce patents against subsequent improvements or that were neither disclosed nor contemplated by the initial inventor at filing. This conflicts with two foundational requirement in patent law: that inventors both provide public notice of the claimed invention and enable a skilled artisan in the technical field to make and use the full scope of the claimed invention at the time of filing. Through the doctrine of equivalents (DOE), courts permit initial inventors to capture later-developed variants as infringements, even when such variants would fail statutory notice and disclosure requirements if claimed in the original patent application. This approach to the DOE causes tension between two essential patent policies: adequately rewarding pioneering inventors while preserving meaningful incentives for subsequent improvers.
This Essay proposes a recalibrated equivalence analysis that considers both parties’ contributions: the initial patentee’s enabling disclosure at filing and the technical merit of the subsequent improvement at the time of its development. This approach distinguishes between trivial technological advances warranting equivalence (and infringement) and substantial technical advances that do not. Adopting this approach would strike the right balance between the competing interests of initial inventors and subsequent improvers while also honoring patent law’s commitment to public notice and disclosure.
Seymore, Sean B, Patenting the Future (September 15, 2026), Texas A&M Law Review, volume 15, forthcoming 2027; Vanderbilt Law Research Paper No 7468679.
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