Immunity from prosecution (international law)

Functional immunity

Functional immunity arises from customary international law and treaty law and confers immunities on those performing acts of state (usually a foreign official). Any person who in performing an act of state commits a criminal offence is immune from prosecution. This is so even after the person ceases to perform acts of state. Thus it is a type of immunity limited in the acts to which it attaches (acts of state) but will only end if the state itself ceases to exist. This immunity, though applied to the acts of individuals, is an attribute of a state, and is based on the mutual respect of states for sovereign equality and state dignity. States thus have a significant interest in upholding the principle in international affairs: if a state's officials are to be tried at all for anything, it will be at home.

State offices usually recognised as automatically attracting this immunity are the head of state or head of government, senior cabinet members, ambassadors and the foreign and defence ministers. Many countries have embodied these immunities in domestic law. States regularly assert that every official acting in their official capacity is immune from prosecution by foreign authorities (for non-international crimes) under the doctrine of ratione materiae. Such officers are immune from prosecution for everything they do during their time in office. For example, an English court held that a warrant could not be issued for the arrest of Robert Mugabe on charges of international crimes on the basis that he was a presently serving Head of State at the time the proceedings were brought. Other examples are the attempts to prosecute Fidel Castro in Spain and Jiang Zemin in the USA.

However, the moment the accused leave their offices, they are liable to be prosecuted for crimes committed before or after their term in office, or for crimes committed whilst in office in a personal capacity (subject to jurisdictional requirements and local law).

It may be the case that functional immunity is itself being eroded. Recent developments in international law suggest that ratione materiae, whilst it may remain available as a defence to prosecution for local or domestic crimes or civil liability, is not a defence to an international crime. (International crimes include crimes against humanity, war crimes, and genocide.)

The indictment in 1998 in Spain and subsequent arrest in the UK of Chile's Pinochet was a landmark decision by European judges and the House of Lords, which in his case set aside functional as well as local immunities, by ruling that the crimes Pinochet was accused of fell within the scope of the United Nations Convention against Torture, being international crimes so heinous that they are:

The principle of depriving immunity for international crimes was developed further in the jurisprudence of the International Criminal Tribunal for the Former Yugoslavia, particularly in the Karadzic, Milosevic, and Furundzija cases (though care should be taken when considering ICTY jurisprudence due to its ad-hoc nature). This was also the agreed position as between the parties in their pleadings in the International Court of Justice Case Concerning the Arrest Warrant of 11 April 2000 (Democratic Republic of the Congo v. Belgium).

In 2004 the Appeals Chamber of the Special Court for Sierra Leone held that indicted Liberian president Charles Taylor could not invoke his Head of State immunity to resist the charges against him, even though he was an incumbent Head of State at the time of his indictment. However, this reasoning was based on the construction of the court's constituent statute, that dealt with the matter of indicting state officials. In any case, Taylor had ceased to be an incumbent Head of State by the time of the court's decision so the arresting authorities would have been free to issue a fresh warrant had the initial warrant been overturned. Nevertheless, this decision may signal a changing direction in international law on this issue.

It is worth noting that the decisions of the Spanish and UK courts in relation to Pinochet were based directly on existing domestic law, which had been enacted to embody the obligations of the treaty. Although a state party to the treaty, Chile itself had not enacted such laws, which define the specified international crimes as crimes falling within the domestic criminal code and making them subject to universal jurisdiction, and thus Chile could only prosecute on the basis of its existing criminal code - murder, abduction, assault etc, but not genocide or torture.

The reasons commonly given for why this immunity is not available as a defence to international crimes is straight forward: (1) that genocide, war crimes and crimes against humanity are not acts of state. Criminal acts of the type in question are committed by human actors, not states; and (2) we cannot allow the jus cogens nature of international crimes, i.e. the fact that they are non-derogable norms, to be eroded by immunities.

However, the final judgment of the ICJ regarding immunity may have thrown the existence of such a rule limiting functional immunities into doubt. See in this respect the criticism of the ICJ's approach by Wouters, Cassese and Wirth among others, though some such as Bassiouni claim that the ICJ affirmed the existence of the rule.

Regarding claims based on the idea that a senior state official committing International crimes can never be said to be acting officially, as Wouters notes: "This argument, however, is not waterproof since it ignores the sad reality that in most cases those crimes are precisely committed by or with the support of high-ranking officials as part of a state’s policy, and thus can fall within the scope of official acts." Academic opinion on the matter is divided and indeed only the future development of International Customary law, possibly accelerated by states exercising universal jurisdiction over retired senior state officials, will be able to confirm whether state sovereignty has now yielded partially to internationally held human rights values.

In November 2007, French prosecutors refused to press charges against former US Secretary of Defense Donald Rumsfeld for torture and other alleged crimes committed during the course of the US invasion of Iraq, on the grounds that heads of state enjoyed official immunity under customary international law, and they further claimed that the immunity exists after the official has left office. However, other jurists hold that heads of state and state officials still can be prosecuted by foreign courts after the end of their terms of office.

Personal immunity

This type of immunity arises from customary international law and confers immunity on people holding a particular office from the civil, criminal, and administrative jurisdiction. This immunity is extended to diplomatic agents and their families while posted abroad (and is also valid for their transfer to or from that post, and is only valid for the country to which they are posted). Under personal immunity, private residence, papers, correspondence, and property of an official enjoying personal immunities are inviolable.

According to Cassese (2005), personal immunities are extended to cover personal activities of an official, including immunity from arrest and detention (though the host state may declare the person persona non grata), immunity from criminal jurisdiction, immunity from the civil and administrative jurisdiction of the host state. No immunities hold for private immoveable property unless held on behalf of the sending state for the purposes of the mission, issues of succession, professional or commercial activity exercised outside of official functions, or where the official has voluntarily submitted to the proceedings.Personal immunities cease with the cessation of the post.

This type of immunity is not for the official's personal benefit but is based on the need for states to function effectively and hence not be deprived of their most important officials.

Cases of overlap

When a person, who enjoys a personal immunity and has committed a criminal act covered also by functional immunity, leaves office, the personal immunity is removed as usual. This is what happened in the Pinochet case before the House of Lords. Senator Pinochet was only able to be extradited to face charges that were not caught by the functional immunity (and also met the separate tests for extradition under English law).