Equitable Defenses in Patent Law

Abstract

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.

Keywords: unclean hands, equitable defenses, law and equity, patent, patents, law, misuse, inequitable conduct, estoppel, laches, interpretive, dynamic, faithful agent