Extraneous factors in judicial decisions

Shai Danziger, Jonathan Levav, Liora Avnaim-Pesso

Research output: Contribution to journalArticlepeer-review

683 Scopus citations


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.

Original languageEnglish
Pages (from-to)6889-6892
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number17
StatePublished - 26 Apr 2011


  • Decisionmaking
  • Ego depletion
  • Expert decisionmaking
  • Legal realism
  • Mental depletion

ASJC Scopus subject areas

  • General


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