Does justice depend on eating a sandwich?

Jonathan Levav, Assistant Professor at Columbia Business School, talks about his paper that was recently published in Proceedings of the National Academy of Sciences. He answers the question:

Does justice depend on eating a sandwich?

The varied reactions to the paper by the scientific community (based on my conversations) nicely illustrates the tension between theory development and applications. Some behavioral scientists  question whether the finding advances our basic understanding of the human condition. After all, there is  already a large literature that documents that fatigue influences the quality of decisions (e.g., tired air traffic controllers), and there already exists a large literature about the fallibility of expert judgments.  Although I agree that peer-reviewed journals should primarily focus on theory development, I think that there is room for provocative demonstrations (that follow from well-accepted theory) in new, important domains such as the judicial system.

Reactions to the paper in the press illustrates the tension. The Economist reacts:

In truth, these results, though disturbing, are unsurprising. Judges may be trained to confine themselves to the legally relevant facts before them. But they are also human, and thus subject to all sorts of cognitive biases which can muddy their judgment. Other fields are familiar with human imperfectibility, and take steps to ameliorate it. Pilots, for instance, are given checklists to follow, partly in order to combat the effects of fatigue. Lorry drivers in the European Union are not allowed to drive for more than four and a half hours without taking a break. Dr Danziger’s co-author, Jonathan Levav of Columbia University in New York, wonders whether the law should consider similar arrangements. Some, of course, already do. English judges, legendary for their prandial proclivities, are way ahead of him.

Note: prandial means “of or relating to a meal.”


Shai Danziger, Jonathan Levav, and Liora Avnaim-Pesso, (2011). Extraneous factors in judicial decisions. Proceedings of the National Academy of Sciences. Abstract:

Are judicial rulings based solely on laws and facts? Legal formalism holds that judges apply legal reasons to the facts of a case in a rational, mechanical, and deliberative manner. In contrast, legal realists argue that the rational application of legal reasons does not sufficiently explain the decisions of judges and that psychological, political, and social factors influence judicial rulings. We test the common caricature of realism that justice is “what the judge ate for breakfast” in sequential parole decisions made by experienced judges. We record the judges’ two daily food breaks, which result in segmenting the deliberations of the day into three distinct “decision sessions.” We find that the percentage of favorable rulings drops gradually from ≈65% to nearly zero within each decision session and returns abruptly to ≈65% after a break. Our findings suggest that judicial rulings can be swayed by extraneous variables that should have no bearing on legal decisions.

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