The Ex Ante Function of the Criminal Law

Law and Society Review, Vol. 35, pp. 165-189, 2001

23 Pages Posted: 7 Feb 2005 Last revised: 7 Sep 2008

See all articles by John M. Darley

John M. Darley

Princeton University

Kevin M. Carlsmith

Colgate University - Psychology Department

Paul H. Robinson

University of Pennsylvania Carey Law School


Criminal legal codes draw clear lines between permissible and illegal conduct, and the criminal justice system counts on people knowing these lines and governing their conduct accordingly. This is the ex ante function of the law; lines are drawn, and because citizens fear punishments or believe in the moral validity of the legal codes they do not cross these lines. But do people in fact know the lines that legal codes draw? The fact that several states have adopted laws that deviate from other state laws enables a field experiment to address this question. Residents (N = 203) of states (Wisconsin, Texas, North Dakota, and South Dakota) that had adopted a minority position on some aspect of criminal law reported the relevant law of their state to be no different than did citizens of majoritarian states. Path analyses using structural equation modeling suggest that people make guesses about what their state law holds by extrapolating from their personal view of whether or not the act in question ought to be criminalized.

A legal code in a complex society is designed to have several functions. First, it is designed to announce beforehand the rules by which citizens must conduct themselves, on pain of criminal punishment. Second, if a person violates one of these rules of conduct, the criminal law must determine whether the violator is to be held criminally liable. Third, another part of its adjudicatory function, where liability is imposed the law must determine the general range, or grade, of punishment to be imposed.

It is the first function that is of interest to us here, the so-called ex ante function of the criminal law. The code announces in advance what actions count as criminal; thus the citizenry can use the announcement to guide their actions to avoid criminal conduct. The law, in other words, draws bright lines between allowable and unallowable conduct, and those lines enable the citizens to regulate their conduct so they do not break the laws. To use a familiar metaphor, the criminal law specifies what sorts of actions are out of bounds, and the penalties for those actions, so the players will stay in bounds. The criminal justice system relies on people knowing the law and knowing where the boundaries for their conduct lie. Ignorance does not excuse unlawful conduct, a fact summarized in the phrase ignorance of the law is no excuse. Such a rule is defended as a useful means of creating an incentive for citizens to learn the law.

Keywords: Criminal code, ex ante, criminal law

JEL Classification: K14

Suggested Citation

Darley, John M. and Carlsmith, Kevin M. and Robinson, Paul H., The Ex Ante Function of the Criminal Law. Law and Society Review, Vol. 35, pp. 165-189, 2001, Available at SSRN:

John M. Darley

Princeton University ( email )

1-N-17 Green Hall
Princeton, NJ 08544
United States
609-258-3000 (Phone)

Kevin M. Carlsmith

Colgate University - Psychology Department ( email )

13 Oak Drive
Hamilton, NY 13346
United States


Paul H. Robinson (Contact Author)

University of Pennsylvania Carey Law School ( email )

3501 Sansom Street
Philadelphia, PA 19104
United States

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