Decision-making in Japanese plea bargaining: Impact of guilt, punishment severity, probability of conviction, and intimacy with the accused

In 2018, Japan introduced a plea bargaining system called "Japanese plea bargaining." This system offers rewards for the provision of information about another person's crime. While the potential risk of false statements has been noted, there have been few actual cases, and a thorough examination has not been conducted. Therefore, this study conducted two experiments to examine the variables that influence the decision-making of those who are offered rewards for information. Experiment 1 demonstrated the impact of the informant's guilt or innocence on decision-making, with a higher acceptance rate reported in cases of guilt. Experiment 2 demonstrated the influence on decision-making of the association between the guilt or innocence of the informant and the degree of intimacy between the accused and the informant. In both experiments, when the informant was innocent, a certain number of offers were accepted, highlighting the likelihood of false statements and the associated risk of wrongful conviction in Japanese plea bargaining.