The failure of the collective security of the League of Nations led to the realization that a universal system of security could only be effective if nations agreed to some limitation of their national sovereignty with regard to their right to belligerency, and if the Security Council which had been a "closed shop" during League of Nations times, would open itself up to UN Members who would cede constitutional powers in favor of collective security. Like the German Article 24, which was incorporated in the post-war German Constitution, and which provides for delegating or limiting sovereign powers in favor of collective security, Article 9 was added to the Constitution of Japan during the occupation following World War II.