Equivalency and Patent Law's Possession Paradox
48 Pages Posted: 21 Jan 2009 Last revised: 13 Jun 2012
Under the Federal Circuit's current law, the doctrine of equivalents protects only those technologies that arise after the patent issues. This state of affairs creates a curious paradox: the patentee is afforded protection for that which she did not possess, which runs counter to the general view that patents afford protection for the inventor's creation. This paper explores this paradox and offers two possible means of reconciling it based on principles of fairness. First, patentees should only be protected under the doctrine of equivalents for changes in technology that arise from outside their field of technology. While seemingly simple in application, this approach fails to link the scope of protection to the patent's disclosure. The second would provide protection under the doctrine of equivalents if the patent's disclosure would enable the asserted equivalent at the time of infringement. The patent's disclosure is therefore allowed to grow over time, providing insurance against the patent's obsolescence and effectively extending its life span. This approach offers a better theoretical fit in that it ties the right to exclude to the patent's disclosure. It would provide considerable protection to the patentee, however. In order to keep the doctrine of equivalence in check -- either under the status quo or under the Article's proposal -- the author suggests that those who infringe under the doctrine of equivalents should not be subject to permanent injunctions. In other words, the doctrine of equivalents would operate pursuant to a liability rule, not a property rule. This shift is particularly appropriate given the high transaction costs surrounding patent scope, and particularly equivalency. In this way, the interest of the patentee can be protected to some extent, balanced by the interest in third parties in being able to practice their later-developed technologies.
Keywords: patent, infringement, doctrine of equivalents, equivalency, liability rule, property rule, injunction, enablement, disclosure
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