The factors that experts use to assess criminal responsibility are not very well known. Changes in the importance attributed to certain diagnoses are occasionally mentioned in the literature. The aim of this study is to identify the existence and the nature of such modifications.

We compared the socio-demographic, criminological and psychiatric characteristics of two samples of psychiatric assessments carried out in Geneva, Switzerland in 1973–74 (N = 75) and 1997–98 (N = 94).

The two groups of subjects described by the experts’ reports appear to be quite different in several characteristics. However, the rate at which experts conclude their reports in favour of diminished responsibility was not found to be significantly different. The logistic regression shows that the diagnosis of personality disorder is the only variable that influenced the experts differently for the 1997–98 period compared to the 1973–74 period.

In Geneva, psychiatric experts still continue to ascribe diminished responsibility to offenders suffering from psychosis or depression. However, the population that undergoes psychiatric assessments nowadays has changed considerably.