Document Type


Publication Date

Fall 2020

Publication Title

University of Miami Law Review


unenforceability, laches, estoppel, unclean hands, patent misuse, Patent Act


In patent law, “unenforceability” can have immense consequences. At least five equitable doctrines make up the defense of “unenforceability” as it was codified into the Patent Act in 1952: laches; estoppel; unclean hands; patent misuse; and according to some, inequitable conduct. Yet in the seventy years since incorporation of equitable defenses into the patent statute, the Supreme Court has not clarified their reach. Indeed, twice in the last four years, the Supreme Court avoided giving complete guidance on the crucial questions of whether, and when, such equitable defenses are available to bar damages in cases brought at law.

Several interpretive methods have been proposed for determining the reach of generally worded statutes like the Patent Act. Under a dynamic statutory interpretation, courts would be permitted to develop such statutes in accordance with what the law ought to be. Under a traditional faithful agent approach, in contrast, courts would try to determine the scope as set forth by the legislature, piecing together context and history to frame limited words. The scope of equitable defenses in patent law is an ideal proving ground between these methods, having both historical background for use in traditional approaches and high-stakes social questions that factor into a dynamic approach—what conduct do we allow patentees to engage in before we cut off remedies for infringement on innovations that support our health and modern lifestyle?

Setting the stage of the statutory interpretive battle, this Article examines the historical and statutory bases of equitable limits on patent law, with a particular focus on the substantive equitable defenses of unclean hands and patent misuse. It contrasts the history of equitable defenses such as estoppel, which crossed fully into courts of law well before the merger of law and equity and the Patent Act, with equitable defenses such as laches, unclean hands, and misuse. This Article walks through these defenses’ pre-codification roots and potential statutory interpretations and presents normative and constitutional considerations under the competing interpretive approaches. It also presents a surprising approach to inequitable conduct, arguing that it is not an equitable defense and should no longer result in infectious invalidity. This Article is the first to provide a comprehensive framework for the analysis of equitable defenses in patent law.