Immunity from foreign (domestic) jurisdiction for States and HRSO

1.1. State immunity: par in parem non habet imperium
Codified in the UN Convention on Jurisdictional Immunities of States and Their Property (abbreviated UNCSI), the rules on State immunity are of customary international law. Though in issues governed by certain treaties like the 1972 European Convention, general customary law does not apply. General customary law shall only be excluded when immunity issues between member States of the European Convention arise.

As Article 5 of UNCSI reads:
"A State enjoys immunity, in respect of itself and its property, from the jurisdiction of the courts of another State subject to the provisions of the present Convention".
Subsequently, Art. 6 obliges States to refrain from exercising jurisdiction before its court against another State.

The underlying principle is that all States are sovereign and equal (as Article 2(1) of the UN Charter puts it). Thus, the UNCSI solely applies to immunity from foreign jurisdiction: a State could and should not be prosecuted before a domestic foreign court.  Note that State immunity is derived from State sovereignty, which relates to the rule that incumbent high-ranking State officials are also immune from the jurisdiction of foreign States. States have legal personality, therefore they enjoy immunity ratione personae: immunity from jurisdiction and enforcement.

1.2. Subjects of State immunity
For the purposes of the Convention on Jurisdictional State Immunities, a "State" means, Art. 2(1):
i. the State and its various organs of government;
ii. units of fa ederal State or political subdivisions which are entitled to perform acts in the exercise of sovereign authority and are acting in that capacity;
iii. agencies "  ";
iv representatives of the State, acting in that capacity.

From this follows that incumbent HRSO enjoy full immunity from foreign jurisdiction, a result of the classic view on sovereign immunity, as discussed under para 1.1.

1.3. Relative immunity
A distinction is drawn between acta iure imperii (governmental acts) and acta iure gestionis. States could not enjoy absolute immunity for their acta iure gestionis, see Art. 10(1) of UNCSI:
"If a State engages in a commercial transaction with a foreign natural or juridical person [..] the State cannot invoke immunity from that jurisdictio in a proceeding arising out of that commercial transaction". Paragraph 1 does not apply in case of one of the exceptions, mentioned in the second paragraph of Art. 10.

How does one determine, whether a contract or transaction is an acta iure gestionis? According to Article 2 of the UNCSI, reference should be made primarily to the nature of the contract or transaction; however, its purpose should also be taken into account. The focus shifts from the initial purpose of a transaction, to the nature of a transaction, to prevent States from using the "veil" of acta iure imperii in order to escape their obligations by invoking full immunity from foreign jurisdiction.

Other proceedings in which a State cannot invoke immunity, concern: contracts of employment
(Art. 11), personal injuries and damage to property (Art. 12), ownership (Art. 13), intellectual property (Art. 14)  and so on, see Part III of UNCSI.

1.4. Waiver of immunity
No problems will arise when a State has expressly consented to the exercise of jurisdiction by a foreign court, in the cases, mentioned in Article 7 of UNCSI. A State could be considered to have consented to the exercise of a foreign court implicitly, as Article 8(1) makes clear, unless paras 2-4 of Art. 8 UNCSI apply.

1.5. Jurisdictional Immunities of the State, ICJ 3 February 2012
Ferrini case: Germany v. Italy, Greece intervening
To an important extent, State immunity is based on the rules of customary international law, as the ICJ sets out in paras 53-58 of the 2012 Immunities case.

State immunity does not imply that a State cannot be held responsible for its actions; as was discussed before, State immunity solely implies that a State could not be prosecuted before a domestic foreign court. See para 53:  "The Court is not called upon to decide whether these acts were illegal; the question for the Court is whether or not, in proceedings regarding claims for compensation arising out of those acts, the Italian (domestic) courts were obliged to accord Germany immunity". A State prosecuting another State, could in its turn be held responsible for violating the right to invoke immunity from foreign jurisdiction.

1.5.1. Do the breach of ius cogens and territorial torts allow for denial of immunity?
Does customary international law prevent a State from lawfully invoking immunity in respect of the "Territorial Tort Principle", even is an act on the territory of a forum State was performed iure imperii? The Court considers it is not called upon in the present proceedings to resolve the question, whether there is in customary law a "tort exception" to State immunity to acta iure imperii in general (para 65).
        The Court agrees that the result of Art. 31 of the European Convention as a clause, is that the immunity of a State for the acts of its armed forces, falls out of the Convention and has to be determined by reference to customary law.The consequence is, however, that the inclusion of the "Territorial Tort Principle" cannot be treated as support for the argument that a State is not entitled to immunity for torts, commited by its armed forces (para 68).
       Moreover, State practice in the form of judicial decisions, supports the proposition that State immunity for acta iure imperii continues to extend to civil proceedings for acts occasioning [..] by the armed forces, even if the acts take place on the territory of the forum State. That practice is accompanied by opinio iuris, as a number of national courts made clear that customary law required immunity. The almost complete absence of contrary jurisprudence is significant (para 77).
       The Court concludes that, under customary law, a State is not deprived of immunity by reason of the fact that it is accused of serious violations of international human rights law. The question of whether immunity might apply in criminal proceedings is, however, not an issue in the present case (para 91).
       As to the relationship between ius cogens and State immunity, the Court considers that there exists no conflict between the two legal concepts, as the two sets of rules address different matters. The rules of State immunity are procedural in character and are confined to determining whether or not the courts of one State may exercise jurisdiction in respect of another. They do not bear upon the question whether or not the conduct in respect of which the proceedings are brought, was lawful or unlawful. Recognizing State immunity does not amount to recognizing as lawful the breach of ius cogens and so cannot contravene the principle in Article 41 of the ILC on State Responsibility
(para 93).

2. Immunity from jurisdiction for High-Ranking State Officials (HRSO)
As was set out above, the immunities in respect of HRSO are derived from the principle of sovereign immunity; the immunities of a HRSO are interrelated with State immunity. As a matter of fact, only a State can waive the immunity of an HRSO. An incumbent HRSO enjoys both immunity rationae materiae and rationae personae. Note that, after a HRSO ceases to hold the office, he or she will no longer hold all of the immunities. A State may try a former HRSO in respect of acts committed in a private capacity (Arrest Warrant 2002, DRC Congo v. Belgium, para 61).

2.1. Relevant considerations in the Arrest Warrant Judgment of 11 April 2002
Yerodia Ndombasi case, Congo v. Belgium
2.1.1. HRSO and full immunities, regardless of a official or private capacity
Certain holders of high-ranking office in a State enjoy immunities from jurisdiction in other States, both civil and criminal. It is only the immunity from criminal jurisdiction and the inviolability of an incumbent Minister for Foreign Affairs, that fall for the Court to consider (para 51).
              The rationale behind the immunity for HRSO is as follows. In customary international law, the immunities accorded to [..] are not granted for their personal benefit, but to ensure the effective performance of their functions on behalf of their respective States (para 53).
              When abroad, a HRSO (as is a Minister for Foreign Affairs i.c.) enjoys full immunity from criminal jurisdiction throughout the duration of his office [...] to protect the individual against any act of authority by another State which would hinder him in the performance of his duties (para 54).
In this respect, no distinction can be drawn between actes performed by a HRSO in an "official" capacity, and those claimed to have been performed in a "private" capacity (para 55).

2.1.2. Considerations regarding Opinion ex parte Pinochet
According to Belgium, the Pinochet decision recognizes an exception to the immunity rule when Lord Millett stated that "international law cannot be supposed to have established a crime [..] or when Lord Phillips said that "no established rule of international law requires state immunity ratione materiae to be accorded in respect of prosecution for an international crime" (para 56).
           The Congo cites Lord Browne-Wilkinson's statement that "this immunity, enjoyed by a head of  state in power is a complete immunity, attached to the person of the head of state and rendering him immune from all actions or prosecutions"  (para 57).
           The Court has been unable to deduce from [..] practice that there exists under customary law, any form of exception to the rule according immunity from criminal jurisdiction and inviolability to incumbent Ministers, where they are suspected of having commited war crimes. The rules concerning criminal responsibility of HRSO likewise do not enable to conclude that any such exception exists in customary law in regard to domestic courts (para 58).

2.1.3. Is impunity a result of immunity?
It should be noted that the rules governing the jurisdiction of foreign courts must be distinguished from those, governing jurisdictional immunities; jurisdiction does not imply absence of immunity and absence of immunity does not imply jurisdiction. The obligations of prosecution and extradition of serious crimes that are imposed on States, do in no way affect immunities under customary law, including those of HRSO (para 59).
         The immunity from jurisdiction enjoyed by HRSO does not mean that they enjoy impunity in respect of crimes committed, as immunity from criminal jurisdiction and individual criminal responsibility are quite separate concepts, the first being of a procedural nature, the latter being a question of substantive law (para 60).
         Acccordingly, the immunities enjoyed by an incumbent or former HRSO do not represent a bar to criminal prosecution in certain circumstances. The Court nouns four examples, the first being that jurisdictional immunity does not apply to trial in the domestic court of the HRSO; subsequently, the waiver of immunity by the represented State will cease the immunity from foreign jurisdiction; as mentioned, after a HRSO ceases to hold the office, he will no longer enjoy immunity for his acts commited in private (para 61).

2.1.4. Jurisdiction of International Criminal Tribunals
One important remark is that International Criminal Tribunals can trial HRSO in criminal proceedings, as the Rome Statute in Article 27(2) provides that immunities of an incumbent or former HRSO shall not bar the Court from exercising its jurisdiction over such a person.

3. X v. Bow Street Metropolitan Stipendary Magistrate, Ex parte Pinochet Ugarte (No 3)
3.1.1. Defining the scope
The ICY reasoned in its Jurisdictional Immunities case (Ferrini) of 2012, that a clear distinction should be made between State immunity and the criminal jurisdiction of a former HRSO: "Pinochet concerned the immunity of a former Head of State from criminal jurisdiction of another State, not the immunity of the State itself in proceedings to establish its liability to damages"(para 87 Fellini case).

3.1.2 Could torture, committed by a former HRSO, be considered an official act?
Immunity ratione personae attaches to the office, meaning that a former HRSO cannot invoke immunity with respect to acts committed in private during his time in office, while immunity ratione materiae can be invoked for the official acts that have been committed during his time in office.
        Regarding the Pinochet case, it is important to note that "The Republic of Chile accepted that the international law prohibiting torture, has the character of ius cogens or a peremptory norm". Chile is a party to the Torture Convention (Convention Against Torture, CAT).
       The question which has to be answered, is whether the alleged organisation of state torture by Senator Pinochet (if proved) would constitute an official act, committed as a Head of State. It is not enough to say that it cannot be part of his functions to commit a crime. Actions which are criminal under local law, can still have been done officially and therefore give rise to immunity ratione materiae. Can it be said that the commission of a crime which is an international crime against humanity and ius cogens, is an act done in an official capacity on behalf of the state?
       Under the CAT the international crime of torture can only be committed by an official [...] If immunity applies, there can be no case outside of Chile in which a succesful prosecution can be brought (unless the State is prepared to waive its right to its officials' immunity). One of the main objectives of the CAT: universal jurisdiction over torture, committed by HRSO, would be frustrated by upholding immunity for former HRSO.  The notion of continued immunity for former HRSO is inconsistent with the provisions of CAT.