The main difference between the French and American judicial systems is that there is no possibility for the French courts to promote reform of past legislation because of changing notions of constitutional rights. The first reason for the French position is historical: ancient suspicion against the judiciary due to the practices of the 'Parlements,' the sovereign courts of the Ancien Regime (pre-1789). Moreover, as a result of the 15 Constitutions of the past 200 years, French jurists have become rather 'blases' as to the preeminent function of a document which has little chance to last more than a few decades. The Conseil constituionnel, whose main function is to supervise the constitutional conformity of acts of Parliament, does not perform this function as a judicial body. The legality of executive and administrative regulation is examined by both the administrative and criminal courts. The regular administrative courts and the Conseil d'Etat, the supreme administrative court, have steadily refused to become constitutional judges. In addition, the two French Supreme Courts do not develop reasons in the ways U.S. courts do. The underlying justification at law is the principle of separation of powers and, since 1875 and the Constitution of the 3rd Republic, the sovereignty of Parliament. Since the end of the 19th century the courts have admitted that the legal system is not only the sum of all existing statutes and regulations, but that it also includes general principles of administrative law, derived from natural justice, and fundamental rights which exist outside and above written rules. The Cour de Cassation, the supreme ordinary court, has even included the general principles of law in the flexible notion of public policy ('ordre public'). The general principles and most of the fundamental rights now find support in the present Constitution (1958) and share its moral, if not legal, prestige. Although the courts are powerless before an allegedly unconstitutional statute, they are not when confronted with a private document or an administrative regulation. The Cour de Cassation, the Conseil constitutionnel, and the Conseil d'Etat may be called upon to increase their exercise of conflicting decisions. The emerging issue of precedence of international agreements over national laws may bring the French courts closer to judicial review. Twenty-seven footnotes are included.