Judicial Error by Groups and Individuals

Tinbergen Institute Discussion Paper No.12-029/1

36 Pages Posted: 28 Mar 2012

See all articles by Frans van Dijk

Frans van Dijk

University of Amsterdam - Amsterdam School of Economics (ASE)

Joep Sonnemans

University of Amsterdam - Amsterdam School of Economics (ASE)

Ed Bauw

University of Amsterdam

Date Written: March 27, 2012

Abstract

In criminal cases judges evaluate and combine probabilistic evidence to reach verdicts. Unavoidably, errors are made, resulting in unwarranted conviction or acquittal of defendants. This paper addresses the questions (1) whether hearing cases by teams of three persons leads to less error than hearing cases alone; (2) whether deliberation leads to better decisions than mechanical aggregation of individual opinions; and (3) whether participating in deliberations improves future individual decisions. We find that having more than one judge consider cases reduces error effectively. This does not mean that it is necessary to deliberate about all cases. In simple cases many errors can be avoided by mechanical aggregation of independent opinions, and deliberation has no added value. In difficult cases discussion leads to less error. The advantage of deliberation goes beyond the case at hand: although we provide no feedback about the quality of verdicts, it improves individual decisions in subsequent cases.

Keywords: judicial decision making, experiment, law and economics

JEL Classification: C91, C92, K14

Suggested Citation

van Dijk, Frans and Sonnemans, Joep and Bauw, Ed, Judicial Error by Groups and Individuals (March 27, 2012). Tinbergen Institute Discussion Paper No.12-029/1, Available at SSRN: https://ssrn.com/abstract=2029647 or http://dx.doi.org/10.2139/ssrn.2029647

Frans Van Dijk (Contact Author)

University of Amsterdam - Amsterdam School of Economics (ASE) ( email )

Roetersstraat 11
Amsterdam, North Holland 1018 WB
Netherlands

Joep Sonnemans

University of Amsterdam - Amsterdam School of Economics (ASE) ( email )

Roetersstraat 11
1018 WB Amsterdam
Netherlands
+31 20 525 4249 (Phone)
+31 20 525 5283 (Fax)

Ed Bauw

University of Amsterdam ( email )

Spui 21
Amsterdam, 1018 WB
Netherlands