IT WAS COMMON PRACTICE AMONG THE HEBREWS AND IN PRE-10TH CENTURY ENGLAND TO LEAVE LEGAL PROBLEMS RELATING TO OFFENDERS' MENTAL DEFICIENCY TO THE JUDGE'S DISCRETION. THE 1843 MC'NAGHTEN AFFAIR IN ENGLAND REKINDLED INTERNATIONAL DEBATE ABOUT THE LEGAL RESPONSIBILITY OF THE MENTALLY HANDICAPPED. EVEN TODAY, ONE OF THE SERIOUS PROBLEMS FACING CRIMINOLOGISTS IS HOW TO DEAL WITH THE LARGE GROUP OF OFFENDERS WHO ARE MENTALLY ABNORMAL BUT NOT INSANE. THE FRENCH SYSTEM IS DISCUSSED IN TERMS OF TRADITIONAL THEORIES OF PENAL RESPONSIBILITY AND NEW DOCTRINES OF SOCIAL DEFENSE, THE DEMENTIA NOTION OF THE 1810 PENAL CODE, AND 1955 AND 1976 RECOMMENDATIONS OF LEGAL REFORM COMMISSIONS. THEN THE MC'NAGHTEN RULES REGARDING DISEASE OF THE MIND, NATURE AND QUALITY OF THE ACT, AND THE CONCEPT OF WRONGS ARE DESCRIBED FOR THE ENGLISH SYSTEM. THE DISCUSSION COVERS PROPOSED MODIFICATIONS OF THESE RULES TO INCLUDE SUBSTITUTING A MEDICAL COMMISSION FOR INDIVIDUAL PARTIES' PSYCHIATRISTS, AND THE ADOPTION OF A BROAD DEFINITION OF MENTAL DISORDERS THAT AFFECT LEGAL RESPONSIBILTY. THE EVOLUTION OF THE ISRAELI CONCEPT OF MENTAL INCOMPETENCE IS OUTLINED THROUGH DISCUSSIONS OF SPECIFIC LAWS AND CONDITIONS CONSTITUTING MENTAL DEFICIENCY. FREEDOM OF CHOICE IN THE COMMISSION OF A CRIME, CONSCIOUS AND UNCONSCIOUS INVOLUNTARY ACTS AND IRRESISTIBLE IMPULSES, AND THE DEFINITIONS AND DETERMINATION OF MENTAL RETARDATION ARE ALSO CONSIDERED. EXAMINATION OF AMERICAN REJECTION OF THE MC'NAGHTEN RULES SHOWS THAT THE UNITED STATES BASES PROOF OF MENTAL DEFICIENCY ON A SIMILAR KNOWLEDGE TEST WHILE EXPANDING THE MENTAL DEFICIENCY CONCEPT AS AN EXTENUATING CONDITION TO CASES OF IRRESISTIBLE IMPULSES AND INADEQUATE COMPREHENSION OR ABSENCE OF SELF-CONTROL. APPENDIXES CONTAIN TEXTS OF VARIOUS LAWS RELATING TO MENTAL DEFICIENCY AND MENTAL INCOMPETENCE IN CONNECTION WITH CULPABILITY. --IN FRENCH.