Judging Equivalents

Abstract

Courts, patent attorneys, and legal scholars have wrestled with operationalizing the doctrine of equivalents for nearly 150 years. A venerable exception to normal patent infringement rules, the doctrine is deceptively simple to state—it enables patentees to reach beyond the literal wording of their claims, but it remains extremely controversial in its application. This Article traces the doctrine’s origins and explains the reasons for the doctrine’s incoherence, the tension between judges and juries, and the decline of the doctrine. This Article complements the doctrinal discussion with empirical findings of interest to academics and practitioners, including “equitable triggers” such as copying, design-arounds, and pioneer inventions. It also investigates limits such as prosecution history estoppel, the “all-elements” rule, the prior art bar and the public dedication rule.

Keywords: Patent, doctrine of equivalents, empirical