Lateran Treaty
Negotiations for the settlement of the Roman Question began in 1926 between the government of Italy and the Holy See, and culminated in the agreements of the Lateran Pacts, signed—the Treaty says—for King Victor Emmanuel III of Italy by Benito Mussolini, Prime Minister and Head of Government, and for Pope Pius XI by Pietro Gasparri, Cardinal Secretary of State, on 11 February 1929. It was ratified on 7 June 1929. The agreements were signed in the Lateran Palace, hence the name by which they are known.
Legal status of the Holy See
A separate question is whether the Holy See was a subject of international law between 1870, when the Kingdom of Italy annexed the Papal States, and 1929, when the Lateran Treaties were signed. The United States, for instance, suspended diplomatic relations with the Holy See when it lost the Papal States. Similarly, Oppenheim believed that the legal personality of the Papal States became extinct in 1870. For him, between 1870 and 1929, the "Holy See was not an international person," although "it had by custom and tacit consent of most states acquired a quasi-international position". The United Nations International Law Commission noted, nonetheless, that: