Biases in legal decision-making: Comparing prosecutors, defense attorneys, law students, and laypersons

Previous studies of judgment and decision-making in adjudication have largely focused on juries and judges. This body of work demonstrated that legal training and professional experience sometimes affect attitudes and mitigate the susceptibility to cognitive biases, but often they do not. Relatively few experimental studies examined the decisions of prosecutors and defense lawyers, although they play a major role, especially in legal systems where prosecutors have a broad discretion in charging decisions, courts' discretion regarding sentencing is constrained, and plea bargains abound. This study directly compares laypersons, law students, and legal practitioners—including prosecutors and defense lawyers—in terms of their attitudes about the criminal justice system and their cognitive biases. It was found that the outcome bias and the anti-inference bias influenced all groups similarly, but an irrelevant anchor only impacted the decisions of laypersons and law students, and not those of legal professionals. Prosecutors were significantly more inclined to judge a behavior as negligent and reach factual conclusions supporting a conviction. However, the hypothesis that the susceptibility of prosecutors and defense lawyers to cognitive biases would be affected by their role was not borne out. The article considers possible explanations for the reported findings, and discusses their policy implications.