There is no dearth of commentary about the doctrine of equivalents in patent law. Many articles proclaim the doctrine's death, often noting its passage with unbridled delight. Some articles provide empirical evidence to support the assertion that the doctrine of equivalents is dead. Others simply yearn for the doctrine to fade from use, pointing out that no court has "articulated a convincing rationale" for the doctrine's continued use. But maybe these scholars have it wrong. It may be true that the instances of doctrine of equivalents analysis in patent cases are on the decline and successful outcomes based on the doctrine waning further. But these observations tell only a small part of the story. This Article contends that, despite evidence to the contrary, the death of the doctrine of equivalents has been greatly exaggerated.
Kristen Osenga, A Penguin's Defense of the Doctrine of Equivalents, 6 N.Y.U. J.L. & Liberty 313 (2011).