The Permanent Court of International Justice, often called the World Court, existed from 1922 to 1946. It was an international court attached to the League of Nations. Created in 1920 (although the idea of an international court was several centuries old), the Court was initially well-received from states and academics alike, with many cases submitted to it for its first decade of operation. Between 1922 and 1940 the Court heard a total of 29 cases and delivered 27 separate advisory opinions. With the heightened international tension in the 1930s, the Court became less used. By a resolution from the League of Nations on 18 April 1946, both the Court and the League ceased to exist and were replaced by the International Court of Justice and the United Nations. The Court's mandatory jurisdiction came from three sources: the Optional Clause of the League of Nations, general international conventions and special bipartite international treaties. Cases could also be submitted directly by states, but they were not bound to submit material unless it fell into those three categories. The Court could issue either judgments or advisory opinions. Judgments were directly binding but not advisory opinions. In practice, member states of the League of Nations followed advisory opinions anyway for fear of possibly undermining the moral and legal authority of the Court and the League. History Founding and early years An international court had long been proposed; Pierre Dubois suggested it in 1305 and Émeric Crucé in 1623. An idea of an international court of justice arose in the political world at the First Hague Peace Conference in 1899, where it was declared that arbitration between states was the easiest solution to disputes, providing a temporary panel of judges to arbitrate in such cases, the Permanent Court of Arbitration. At the Second Hague Peace Conference in 1907, a draft convention for a permanent Court of Arbitral Justice was written although disputes and other pressing business at the Conference meant that such a body was never established, owing to difficulties agreeing on a procedure to select the judges. The outbreak of the First World War, and, in particular, its conclusion made it clear to many academics that some kind of world court was needed, and it was widely expected that one would be established. Article 14 of the Covenant of the League of Nations, created after the Treaty of Versailles, allowed the League to investigate