Measuring, Monitoring, and Managing Legal Complexity

55 Pages Posted: 19 Feb 2015 Last revised: 2 Dec 2015

See all articles by J. B. Ruhl

J. B. Ruhl

Vanderbilt University - Law School

Daniel Martin Katz

Illinois Tech - Chicago Kent College of Law; Bucerius Center for Legal Technology & Data Science; Stanford CodeX - The Center for Legal Informatics; 273 Ventures

Date Written: February 17, 2015


The American legal system is often accused of being “too complex.” For example, most Americans believe the Tax Code is too complex. But what does that mean, and how would one prove the Tax Code is too complex? The descriptive claim that an element of law is complex, and the normative claim that it is too complex, should be empirically testable hypotheses, yet in fact very little is known about how to measure legal complexity, much less to monitor and manage it.

Legal scholars have begun to employ the science of complex adaptive systems, also known as complexity science, to probe these kinds of descriptive and normative questions about the legal system. This body of work has focused primarily on developing theories of legal complexity and positing reasons for, and ways of, managing it. Legal scholars thus have skipped the hard part — developing quantitative metrics and methods for measuring and monitoring law’s complexity. But the theory of legal complexity will remain stuck in theory until it moves to the empirical phase of study, and thinking about ways of managing legal complexity is pointless if there is no yardstick for deciding how complex the law should be. In short, the theory of legal complexity cannot be put to work without more robust empirical tools for identifying and keeping track of complexity in legal systems.

This Article explores legal complexity at a depth not previously undertaken in legal scholarship. Part I orients the discussion by briefly reviewing the scholarship using complexity science to develop descriptive, prescriptive, and ethical theories of legal complexity. Parts II through IV then shift to the empirical front, identifying potentially useful metrics and methods for studying legal complexity. Part II draws from complexity science to develop methods that have or might be applied to measure different features of legal complexity, including metrics for agents, trees, networks, computation, feedback, and emergence. Part III proposes methods for monitoring legal complexity over time, in particular by conceptualizing what we call Legal Maps — a multi-layered, active representation of the legal system network at work. Part IV concludes with a preliminary examination of how the measurement and monitoring techniques could inform interventions designed to manage legal complexity through use of currently available machine learning and user interface design technologies.

Keywords: Tax code, Complexity science, Legal complexity

Suggested Citation

Ruhl, J. B. and Katz, Daniel Martin, Measuring, Monitoring, and Managing Legal Complexity (February 17, 2015). Iowa Law Review, Vol. 101:191, Vanderbilt Public Law Research Paper No. 15-1, Available at SSRN:

J. B. Ruhl (Contact Author)

Vanderbilt University - Law School ( email )

131 21st Avenue South
Nashville, TN 37203-1181
United States

Daniel Martin Katz

Illinois Tech - Chicago Kent College of Law ( email )

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


Bucerius Center for Legal Technology & Data Science ( email )

Jungiusstr. 6
Hamburg, 20355


Stanford CodeX - The Center for Legal Informatics ( email )

559 Nathan Abbott Way
Stanford, CA 94305-8610
United States


273 Ventures ( email )


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