On 17 July 1998, a United Nations Diplomatic Conference adopted the Statute for the International Criminal Court. This was the culmination of a process begun at Nuremberg in the aftermath of the Second World War and leading to the creation of a permanent international tribunal which would have jurisdiction over the most serious international crimes.

Three months later, on 16 October 1998, Senator Augusto Ugarte Pinochet, the former President of Chile, was arrested in London pursuant to a request for his extradition to Spain to face charges for crimes against humanity which had occurred while he was head of state in Chile. This marked the first time a former head of state had been arrested in England on such charges, and it was followed by legal proceedings which confirmed that he was not entitled to claim immunity from the jurisdiction of the English courts for crimes which were governed by an applicable international convention.

Seven months later, on 27 May 1999, President Slobodan Milosevic of the Federal Republic of Yugoslavia was indicted by the Prosecutor of the International Criminal Tribunal for the former Yugoslavia for atrocities committed in Kosovo. This marked the first time that a serving head of state had ever been indicted by an international tribunal.