In the present study, subjective likelihood of defendant’s guilt was compared to the posterior probability of guilt predicted by the Bayes’ theorem to examine whether lay people overestimate the posterior probability of guilt and to explore the types of probability in the Bayes’ theorem that may contribute to the overestimation. The difference of conviction threshold among experimental conditions(type of evidence and recognition of logical circularity) were also tested. Finally, individual’s implicit threshold for the decision to convict was calculated based on a logistic regression model in each experimental condition and its effect on the decision to convict was examined. In the result, participants overestimated the posterior probability of defendant’s guilt regardless of the type of sole evidence; their implicit threshold varied over experimental conditions; and the participants who recognized the logical circularity made the verdict by comparing the threshold and the probative value of sole evidence. In discussion, the factors that may have impacts on lay people’s verdict in criminal trials with sole evidence and the necessity of change in policy were discussed.
Although robbery displays a higher prevalence of involving groups of two or more offenders than other types of violent crimes, there has been little research on differentiating co-offending robberies from lone robberies. To investigate differences among robberies based on the number of offenders involved, we examined 1353 robbery offenses committed in South Korea. Significant differences among robbery offenders across group size were observed with respect to their age, criminal record, occupation, and living status. Additionally, we found notable differences in victim characteristics, including gender, age, victim-offender relationship, and the nature of the victimization. Moreover, differences were noted in offending behaviors, including planning, offense type, method of approach, type of violence, and weapon possession. Furthermore, a number of factors that significantly contributed to predicting the size of the robbery group were identified, including planning, offense type, offender living status, type of violence, and type of victimization. Our study has policy implications for developing early intervention programmes targeting co-offenders and treatment programmes for victims as well as research implications as to how co-offending affects the behaviors of robbery offenders.
Under section 10 of Korean Criminal Act, it exempts or mitigates punishment for mentally disordered offenders. On the other hand, the public fears that mentally disordered offenders are extremely dangerous and views legal insanity as a legal loophole through which many guilty people ‘escape’ criminal punishment. The purpose of this paper is to examine how frequently the insanity defense is used and how successful it is. We collected 1597 lower court cases which questioned defendant’s mental health. Insanity defense succeeds in only about 305 cases of these cases. The analysis of these cases indicates that successful insanity defense in Korea is extremely rare, less than one tenth of US cases. Mentally disordered defendants suffer schizophrenia, mood disorder, and intellectual disability, and they committed personal crimes such as murder, assault, or sexual assault rather than property crimes. In addition, characteristics of mentally disordered offenders are similar to those from previous studies. The legal and psychological implications of these results and future directions for research are discussed.