The colloquium met to discuss three issues: definitions of criminal responsibility and of psychological and pathological factors which may mitigate or exclude such responsibility; problems arising from the use of psychiatric expertise to assess mitigation or exclusion of criminal responsibility; and the impact of such assessments on decisionmaking and on the treatment of mentally ill offenders. These issues were examined from the perspectives of criminal law, forensic psychiatry, and criminology. The colloquium recommended that questions put to psychiatric experts should relate to diagnostic and prognostic assessments as connected with a treatment program. This program would be carried out following sentencing and revised periodically with a view toward therapeutic continuity. The colloquium called on the Council of Europe to promote interdisciplinary research programs in the areas of psychiatric diagnosis and the relationship between mental illness and crime.