Rethinking the PHOSITA in Patent Litigation

38 Pages Posted: 19 Oct 2016 Last revised: 9 Apr 2017

See all articles by Greg Reilly

Greg Reilly

IIT Chicago-Kent College of Law

Date Written: October 18, 2016


This Article was prepared for the Loyola University Chicago Law Journal’s Symposium “Decisions, Decisions: Exploring Factors that Affect the Judicial Decision-Making Process.” It questions the trend in Supreme Court cases and academic commentary toward greater reliance in patent litigation on the hypothetical “person having ordinary skill in the art” (“PHOSITA”) — essentially a person of average abilities in the technical field of the invention. This trend reflects a desire to approach as closely as possible the first-best outcome of accuracy to the technical merits of patent disputes. However, this first-best outcome is impossible given the constraints imposed by lay decision makers. Long-standing proposals to tailor patent litigation institutions to patent law’s technical nature by increasing the technical competence of decision makers have made little headway. If lay decision makers are here to stay, then the optimal approach is to tailor patent law to the needs of these lay decision makers, including by reducing and constraining the PHOSITA’s role. Lay judges and jurors lack the knowledge, training, and experience to reliably apply the PHOSITA’s perspective themselves. Therefore, increased reliance on the PHOSITA equates with increased reliance on expert witnesses, which introduces a host of well-recognized problems. Attempting to approximate the theoretical ideal of technical fidelity through the PHOSITA is misguided due to the errors introduced by the expert witnesses necessitated by lay decision makers. Tailoring patent law to the needs of lay decision makers — including more legalistic and objective doctrines that reduce the role of the PHOSITA — may be optimal in practice, even if second-best in theory.

Keywords: Patent Law, Intellectual Property, Judicial Decision Making, Legal Design, PHOSITA, Judicial Capabilities

Suggested Citation

Reilly, Greg, Rethinking the PHOSITA in Patent Litigation (October 18, 2016). 48 Loyola University Chicago Law Journal 501 (2016) (invited symposium contribution), Available at SSRN:

Greg Reilly (Contact Author)

IIT Chicago-Kent College of Law ( email )

565 W. Adams St.
Chicago, IL 60661-3691
United States

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