Photo of Sean Sullivan

I am a Professor of Law and the Bouma Faculty Fellow in Law at the University of Iowa College of Law. My research focuses on foundational topics in antitrust and evidence—things like why we can infer market power from market shares and what it means for a jury to find the truth of a disputed fact. I also study markets and individual negotiation as an experimental economist. I enjoy coding and system administration and am fascinated by the intersection of technology and law.

Antitrust Law

My antitrust research focuses on the embattled intersection of economic theory and competition policy. I am particularly interested in efforts to draw competitive effects inferences from market structure evidence. The law of horizontal mergers has relied heavily on market share and market concentration evidence since at least the 1960s, but when and why market structure provides useful information for predicting competitive effects has never been clear. One thesis of my antitrust work is that reliance on market structure evidence is fully justified when it is based on an economically grounded approach to defining markets and when it is used to draw appropriate inferences within the scope of specific markets.

example paper antitrust papers

Evidence Law

My evidence scholarship explores the logic—and sometimes illogic—behind explanations of legal fact-finding and the rules of evidence. Relevant evidence is defined by the Federal Rules of Evidence as having any tendency to make a material fact more or less probable than it would be without the evidence. This is puzzling on its face, since the defining characteristic of a "fact" would seem to be its determinacy, not its random fluctuation according to some probability distribution. The unifying theme of my evidence scholarship is that a careful use of probability theory can clarify not just what we are trying to achieve in evidence law, but also how to best operationalize rules of evidence and related instructions.

example paper evidence papers

Law and Economics

My law and economics research uses game theory and experimental economics as tools of legal analysis. I argue, for example, that nondelegation challenges have long overlooked the importance of what it means for Congress to convey "power" in alleged delegations of legislative powers. Using the theory of principal-agent games as a reference, I propose a nuanced understanding of nondelegation doctrine that helps to explain judicial inaction on the subject. Many aspects of negotiation and the litigation process are games in the economic sense of the term, and I find experimental study of settlement bargaining to be a particularly interesting area of research.

example paper law & econ papers


One of my hobbies is network and server administration. When I can find the time, I enjoy tinkering with Proxmox clusters, spinning up Docker and LXC containers, and trying to script my way around redundant tasks in Python and, hopefully soon, Rust. I also build and maintain full-stack web apps for research projects. I am interested in the intersection of technology and law in a way that only someone who lives at that intersection could be.