Jurists since have regarded this principle as still applying to the position of a former Head of State. Thus in the 9th edition of Oppenheim's International Law (1992 Sir Robert Jennings, Q.C. and Sir Arthur Watts, Q.C.) it is said that a Head of State enjoys all the privileges set out as long as he holds that position (i.e. ratione personae) but that thereafter he may be sued in respect of obligations of a private character.

•  "For his official acts as Head of State, he will like any other agent of the State enjoy continuing immunity."

    Satow in Guide to Diplomatic Practice, Fifth Edition, is to the same effect. Having considered the Vienna Convention on Diplomatic Relations of 1961, the New York Convention on Special Missions of 1969 and the European Convention on State Immunity, the editors conclude at page 9:

•  "2. The personal status of a head of a foreign state therefore continues to be regulated by long established rules of customary international law which can be stated in simple terms. He is entitled to immunity--probably without exception--from criminal and civil jurisdiction."

•  "2.4. A head of state who has been deposed or replaced or has abdicated or resigned is of course no longer entitled to privileges or immunities as a head of state. He will be entitled to continuing immunity in regard to acts which he performed while head of state, provided that the acts were performed in his official capacity; in this his position is no different from that of any agent of the state. He cannot claim to be entitled to privileges as of right, although he may continue to enjoy certain privileges in other states on a basis of courtesy."

    In his Hague Lectures on "The Legal Position in International Law on Heads of States et al", Sir Arthur Watts, Q.C. wrote that a former Head of State had no immunity in respect of his private activities taking place whilst he was Head of State. "A Head of State's official acts, performed in his public capacity as Head of State, are however subject to different considerations. Such acts are acts of the State rather than the Head of State's personal acts and he cannot be sued for them even after he has ceased to be Head of State" (pages 88-89).

    One critical difference between a Head of State and the State of course resides in the fact that a Head of State may resign or be removed. As these writers show, customary international law whilst continuing to hold immune the Head of State for acts performed in such capacity during his tenure of the office, did not hold him immune from personal acts of his own. The distinction may not always be easy to draw, but examples can be found. On the one side in the United States was Hatch v. Baez to which I have referred, Nobili v. Charles I of Austria (1921) (Annual Digest of Public International Law Cases, Volume I 1932, Case No. 90, page 136). On the other side, in France is the case of Mellerio v. Isabel de Bourbon ex Queen of Spain, Journal of International Law (1974) (page 32); more recently the former King Farouk was held not immune from suits for goods supplied to his former wife whilst he was Head of State (Review Critique 1964, page 689).

    The reasons for this immunity as a general rule both for the actual and a former Head of State still have force and, despite the changes in the role and the person of the Head of State in many countries, the immunity still exists as a matter of customary international law. For an actual Head of State as was said in United States of America v. Noriega (1990) 746 F. Supp. 1506, the reason was to ensure that "leaders are free to perform their Governmental duties without being subject to detention, arrest or embarrassment in a foreign country's legal system." There are in my view analogous if more limited reasons for continuing to apply the immunity ratione materiae in respect of a former Head of State.

    Rules of customary international law change, however, and as Lord Denning, M.R. said in Trendtex Trading Corporation v. Central Bank of Nigeria [1977] 1 Q.B. 529, "we should give effect to those changes and not be bound by any idea of stare decisis in international law". Thus, for example, the concept of absolute immunity for a Sovereign has changed to adopt a theory of restrictive immunity in so far as it concerns the activities of a State engaging in trade (I Congresso del Partido [1983] A.C. 244). One must therefore ask is there "sufficient evidence to show that the rule of international law has changed?" (p. 556).

    This principle of immunity has, therefore, to be considered now in the light of developments in international law relating to what are called international crimes. Sometimes these developments are through Conventions. Thus, for example, the International Convention against the Taking of Hostages 1979 provides that:

•  "Any person who seizes or detains and threatens to kill, to injure . . . another person . . . in order to compel a third party, namely a State, an international inter-governmental organisation, a natural or juridical person, or a group of persons, to do or to abstain from doing any act as an explicit or implicit condition for the release of the hostage commits the offence of taking hostages."

    States undertake to prosecute if they do not extradite an offender (any offender "without exception whatsoever") through proceedings in accordance with the law of that State, but subject to "enjoyment of all the rights and guarantees provided by the law of the State in the territory of which he is present." This Convention entered into force on 3 June 1983 and was enacted in the United Kingdom in the Taking of Hostages Act 1982 which came into force on 26 November 1982.

    By the Genocide Convention of 1948,

•  "the Contracting Parties confirmed that genocide (being any of the acts specified in article II of the Convention), whether committed in time of peace or in time of war, is a crime under international law which they undertake to prevent and punish".

    By article IV,

•  "Persons committing genocide or any of the other acts enumerated in article III shall be punished, whether they are constitutionally responsible rulers, public officials or private individuals."

The Genocide Act 1969 made the acts specified in article II of the Convention the criminal offence of genocide, but it is to be noted that article IV of the Convention which on the face of it would cover a Head of State was not enacted as part of domestic law. It is, moreover, provided in article VI that persons charged with genocide "shall be tried by a competent tribunal of the State in the territory in which the act was committed, or by such international penal tribunal as may have jurisdiction." It seems to me to follow that if an immunity otherwise exists, it would only be taken away in respect of the State where the crime was committed or before an international tribunal.

    There have in addition been a number of Charters or Statutes setting up international tribunals--There is the Nuremberg Charter in 1945 which gave jurisdiction to try crimes against peace, war crimes and crimes against humanity (Article 6). By Article 7 "the official position of defendants, whether as a Heads of State or responsible officials in Government Departments shall not be considered as freeing them from responsibility or mitigating punishment." A similar provision was found in the Tokyo Convention. In 1993 the international tribunal for the former Yugoslavia was given power to prosecute persons "responsible for serious violations of international humanitarian law" including grave breaches of the Geneva Conventions of 1949, torture and taking civilians as hostages, genocide, crimes against humanity "when committed in armed conflict whether international or internal in character, and directed against any civilian population" including murder, torture, persecution on political racial or religious grounds. In dealing with individual criminal responsibility it is provided in Article 7 that "the official position of any accused person whether as Head of State or Government or as a responsible Government Official shall not relieve such person of criminal responsibility."

    The Statute of the International tribunal for Rwanda (1994) also empowered the tribunal to prosecute persons committing genocide and specified crimes against humanity "when committed as part of a widespread or systematic attack against any civilian population on national political ethnic or other specified grounds." The same clause as to Head of State as in the Yugoslav tribunal is in this Statute.

    The Rome Statute of the International Criminal Court provides for jurisdiction in respect of genocide as defined, crimes against humanity as defined but in each case only with respect to crimes committed after the entry into force of this statute. Official capacity as a Head of State or Government shall in no case exempt the person from criminal responsibility under this statute. Although it is concerned with jurisdiction, it does indicate the limits which States were prepared to impose in this area on the tribunal.

    There is thus no doubt that States have been moving towards the recognition of some crimes as those which should not be covered by claims of State or Head of State or other official or diplomatic immunity when charges are brought before international tribunals.

    Movement towards the recognition of crimes against international law is to be seen also in the decisions of National Courts, in the resolution of the General Assembly of the United Nations 1946, in the reports of the International Law Commission and in the writings of distinguished international jurists.

    It has to be said, however, at this stage of the development of international law that some of those statements read as aspirations, as embryonic. It does not seem to me that it has been shown that there is any State practice or general consensus let alone a widely supported convention that all crimes against international law should be justiciable in National Courts on the basis of the universality of jurisdiction. Nor is there any jus cogens in respect of such breaches of international law which require that a claim of State or Head of State immunity, itself a well established principle of international law, should be overridden. I am not satisfied that even now there would be universal acceptance of a definition of crimes against humanity. They had their origin as a concept after the 1914 War and were recognised in the Nuremberg Tribunal as existing at the time of international armed conflicts. Even later it was necessary to spell out that humanitarian crimes could be linked to armed conflict internally and that it was not necessary to show that they occurred in international conflict. This is no doubt a developing area but states have proceeded cautiously.

    That international law crimes should be tried before international tribunals or in the perpetrator's own state is one thing; that they should be impleaded without regard to a long-established customary international law rule in the Courts of other states is another. It is significant that in respect of serious breaches of "intransgressible principles of international customary law" when tribunals have been set up it is with carefully defined powers and jurisdiction as accorded by the states involved; that the Genocide Convention provides only for jurisdiction before an international tribunal of the Courts of the state where the crime is committed, that the Rome Statute of the International Criminal Court lays down jurisdiction for crimes in very specific terms but limits its jurisdiction to future acts.

    So, starting with the basic rule to be found both in Article 39(2) and in customary international law that a former Head of State is entitled to immunity from arrest or prosecution in respect of official acts done by him in the exercise of his functions as Head of State, the question is what effect, if any, the recognition of acts as international crimes has in itself on that immunity. There are two extreme positions. The first is that such recognition has no effect. Head of State immunity is still necessary for a former Head of State in respect of his official acts; it is long established, well recognised and based on sound reasons. States must be treated as recognising it between themselves so that it overrides any criminal act, whether national or international. This is a clear cut rule, which for that reason has considerable attraction. It, however, ignores the fact that international law is not static and that the principle may be modified by changes introduced in State practice, by Conventions and by the informed opinions of international jurists. Just as it is now accepted that, contrary to an earlier principle of absolute immunity, States may limit State immunity to acts of sovereign authority (acta jure imperii) and exclude commercial acts (acta jure gestionis) as the United Kingdom has done and just as the immunity of a former Head of State is now seen to be limited to acts which he did in his official capacity and to exclude private acts, so it is argued, the immunity should be treated as excluding certain acts of a criminal nature.

    The opposite extreme position is that all crimes recognised as, or accepted to be, international crimes are outside the protection of the immunity in respect of former Heads of State. I do not accept this. The fact even that an act is recognised as a crime under international law does not mean that the Courts of all States have jurisdiction to try it, nor in my view does it mean that the immunity recognised by States as part of their international relations is automatically taken away by international law. There is no universality of jurisdiction for crimes against international law: there is no universal rule that all crimes are outside immunity ratione materiae.

    There is, however, another question to be asked. Does international law now recognise that some crimes are outwith the protection of the former Head of State immunity so that immunity in Article 39 (2) is equally limited as part of domestic law; if so, how is that established? This is the core question and it is a difficult question.

    It is difficult partly because changes in international law take place slowly as states modify existing principles. It is difficult because in many aspects of this problem the appropriate principles of international law have not crystallised. There is still much debate and it seems to me still much uncertainty so that a national judge should proceed carefully. He may have to say that the position as to State practice has not reached the stage when he can identify a positive rule at the particular time when he has to consider the position. This is clearly shown by the developments which have taken place in regard to crimes against humanity. The concept that such crimes might exist was as I have said recognised, for Nuremburg and the Tokyo Tribunals in 1946 in the context of international armed conflict when the tribunals were given jurisdiction to try crimes against humanity. The Affirmation of the Principles of International Law adopted by the United Nations General Assembly in December 1945, the International Law Commission reports and the European Convention on Human Rights and Fundamental Freedoms also recognised these crimes as international crimes. Since then there have been, as I have shown, conventions dealing with specific crimes and tribunals have been given jurisdiction over international crimes with a mandate not to treat as a defence to such crimes the holding of official office including that of Head of State. National Courts as in the Eichmann Case held that they had jurisdiction to deal with international crimes (see also Re Honecker (1984) 80 I.L.R. 36, and Demanjanjuk 776 F 2d 511).

    But except in regard to crimes in particular situations before international tribunals these measures did not in general deal with the question as to whether otherwise existing immunities were taken away. Nor did they always specifically recognise the jurisdiction of, or confer jurisdiction on, National Courts to try such crimes.

    I do not find it surprising that this has been a slow process or that the International Law Commission eventually left on one side its efforts to produce a convention dealing with Head of State immunity. Indeed, until Prosecutor v. Tadic (105 I.L.R. 419) after years of discussion and perhaps even later there was a feeling that crimes against humanity were committed only in connection with armed conflict even if that did not have to be international armed conflict.

    If the States went slowly so must a national judge go cautiously in finding that this immunity in respect of former Heads of State has been cut down. Immunity, it must be remembered, reflects the particular relationship between states by which they recognise the status and role of each others Head and former Head of State.

    So it is necessary to consider what is needed, in the absence of a general international convention defining or cutting down Head of State immunity, to define or limit the former Head of State immunity in particular cases. In my opinion it is necessary to find provision in an international convention to which the State asserting, and the State being asked to refuse, the immunity of a former Head of State for an official act is a party; the convention must clearly define a crime against international law and require or empower a state to prevent or prosecute the crime, whether or not committed in its jurisdiction and whether or not committed by one of its nationals; it must make it clear that a National Court has jurisdiction to try a crime alleged against a former Head of State, or that having been a Head of State is no defence and that expressly or impliedly the immunity is not to apply so as to bar proceedings against him. The convention must be given the force of law in the National Courts of the State; in a dualist country like the United Kingdom that means by legislation, so that with the necessary procedures and machinery the crime may be prosecuted there in accordance with the conditions to be found in the convention.

    In that connection it is necessary to consider when the pre-existing immunity is lost. In my view it is from the date when the national legislation comes into force, although I recognise that there is an argument that it is when the convention comes into force, but in my view nothing earlier will do. Acts done thereafter are not protected by the immunity; acts done before, so long as otherwise qualifying, are protected by the immunity. It seems to me wrong in principle to say that once the immunity is cut down in respect of particular crimes it has gone even for acts done when the immunity existed and was believed to exist. Equally, it is artificial to say that an evil act can be treated as a function of a Head of State until an international convention says that the act is a crime when it ceases ex post facto to have been a function. If that is the right test, then it gives a clear date from which the immunity was lost. This may seem a strict test and a cautious approach, but in laying down when States are to be taken to be taken as abrogating a long established immunity it is necessary to be satisfied that they have done so.

The Crimes Alleged

    What is the position in regard to the three groups of crimes alleged here: torture, genocide and taking hostages?

    The Torture Convention of 10 December 1984 defines torture as severe pain or suffering intentionally inflicted for specific purposes, "by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity."

    Each State Party is to ensure that all acts of torture are offences under its criminal law and to establish jurisdiction over offences committed in its territory, or by a national of that State or, if the State considers it appropriate, when the victim is a national of that State (Article 5). It must also establish jurisdiction where, "the alleged offender is present under its jurisdiction and it does not extradite pursuant to Article 8." Thus, where a person is found in the territory of a State in the cases contemplated in Article 5, then the State must, by Article 7: "if it does not extradite him, submit the case to its competent authorities for the purpose of prosecution." States are to give each other the greatest measure of assistance in connection with criminal proceedings.

    The important features of this Convention are: (1) that it involves action "by a public official or other person acting in an official capacity"; (2) that by Articles 5 and 7, if not extradited, the alleged offender must be dealt with as laid down; and (3) Chile was a State Party to this Convention and it therefore accepted that, in respect of the offence of torture, the United Kingdom should either extradite or take proceedings against offending officials found in its jurisdiction.

    That Convention was incorporated into English law by section 134 of the Criminal Justice Act 1988. Section 134(1) and (2) provides:

•  "(1) A public official or person acting in an official capacity, whatever his nationality, commits the offence of torture if in the United Kingdom or elsewhere he intentionally inflicts severe pain or suffering on another in the performance or purported performance of his official duties."

•  "(2) A person not falling within subsection (1) above commits the offence of torture, whatever his nationality, if:-   (a) in the United Kingdom or elsewhere he intentionally inflicts severe pain or suffering on another at the instigation or with the consent or acquiescence:-    (i) of a public official; or      (ii) of a person acting in an official capacity; and   (b) the official or other person is performing or purporting to perform his official duties when he instigates the commission of the offence or consents to or acquiesces in it."

If committed other than in the United Kingdom lawful authority, justification or excuse under the law of the place where the torture was inflicted is a defence, but in Chile the constitution forbids torture.

    It is thus plain that torture was recognised by the State Parties as a crime which might be committed by the persons, and be punishable in the States, referred to. In particular, the Convention requires that the alleged offender, if found in the territory of a State Party, shall be, if not extradited, submitted to the prosecution authorities.

    This, however, is not the end of the enquiry. The question remains--have the State Parties agreed, and in particular have the United Kingdom and Chile, which asserts the immunity, agreed that the immunity enjoyed by a former Head of State for acts ratione materiae, shall not apply to alleged crimes of torture? That depends on whether a Head of State, and therefore a former Head of State, is covered by the words "a public official or a person acting in that capacity". As a matter of ordinary usage, it can obviously be argued that he is. But your Lordships are concerned with the use of the words in their context in an international Convention. I find it impossible to ignore the fact that in the very Conventions and Charters relied on by the appellants as indicating that jurisdiction in respect of certain crimes was extended from 1945 onwards, there are specific provisions in respect of Heads of State as well as provisions covering officials. These provisions may relate to jurisdiction, or to the removal of a defence, and immunity of course is different from each, both as a concept and in that it is only pleadable in bar to proceedings in National Courts. These provisions do, however, serve as a guide to indicate whether States have generally accepted that former Heads of State are to be regarded as "public officials" and accordingly that the immunity has been taken away from former Heads of State in the Torture Convention.

    Thus, in the Nuremberg Charter 1945 (Article 7), the official position of defendants "whether as Heads of State or responsible officials" does not free them from responsibility. In the Genocide Convention (1948) persons committing the act shall be punished "whether they are constitutionally responsible rulers, public officials or private individuals". In the Yugoslav and Rwanda Tribunals,

•  "The official position of any accused person, whether as Head of State or Government or as a responsible Government official"

is not a defence (Article 7). Even as late as the Rome Statute on the International Criminal Court by Article 27 "official capacity as a Head of State or Government ... or Government official" is not exempted from criminal responsibility.

    In these cases, States have not taken the position that the words public or government official are wide enough to cover Heads of State or former Heads of State, but that a specific exclusion of a defence or of an objection to jurisdiction on that basis is needed. It is nothing to the point that the reference is only to Head of State. A Head of State on ceasing to be a Head of State is not converted into a public official in respect of the period when he was a Head of State if he was not so otherwise. This is borne out by the experience of the International Law Commission in seeking to produce a draft in respect of State immunity. The reports of its meeting show the difficulties which arose in seeking to deal with the position of a Head of State.

    I conclude that the reference to public officials in the Torture Convention does not include Heads of State or former Heads of State, either because States did not wish to provide for the prosecution of Heads of State or former Heads of State or because they were not able to agree that a plea in bar to the proceedings based on immunity should be removed. I appreciate that there may be considerable political and diplomatic difficulties in reaching agreement, but if States wish to exclude the long established immunity of former Heads of State in respect of allegations of specific crimes, or generally, then they must do so in clear terms. They should not leave it to National Courts to do so because of the appalling nature of the crimes alleged.

    The second provisional warrant does not mention genocide, though the international warrant and the request for extradition do. The Genocide Convention in Article 6 limits jurisdiction to a tribunal in the territory in which the act was committed and is not limited to acts by public officials. The provisions in Article 4 making "constitutionally responsible rulers" liable to punishment is not incorporated into the English Genocide Act of 1948. Whether or not your Lordships are concerned with the second international warrant and the request for extradition (and Mr. Nicholls, Q.C. submits that you are not), the Genocide Convention does not therefore satisfy the test which I consider should be applied.

    The Taking of Hostages Convention which came into force in 1983 and the Taking of Hostages Act 1982 clearly make it a crime for "any person, whatever his nationality" who "in the United Kingdom or elsewhere to take hostages for one of the purposes specified." This again indicates the scope both of the substantive crime and of jurisdiction, but neither the Convention nor the Act contain any provisions which can be said to take away the customary international law immunity as Head of State or former Head of State.

    It has been submitted that a number of other factors indicate that the immunity should not be refused by the United Kingdom--the United Kingdom's relations with Chile, the fact that an amnesty was granted, that great efforts have been made in Chile to restore democracy and that to extradite the respondent would risk unsettling what has been achieved, the length of time since the events took place, that prosecutions have already been launched against the respondent in Chile, that the respondent has, it is said, with the United Kingdom Government's approval or acquiescence, been admitted into this country and been received in official quarters. These are factors, like his age, which may be relevant on the question whether he should be extradited, but it seems to me that they are for the Secretary of State (the executive branch) and not for your Lordships on this occasion.

The Alternative Basis--Acts of State--and Non-Justiciability

    United States Courts have been much concerned with the defence of act of state as well as of sovereign immunity. They were put largely on the basis of comity between nations beginning with the Schooner Exchange v. M'Faddon (supra). See also Underhill v. Hernandez 168 US 250. In Banco National de Cuba v. Sabbatino 307F 2d 845 (1961) it was said that "the Act of State Doctrine briefly stated that American Courts will not pass on the validity of the acts of foreign governments performed in their capacities as sovereigns within their own territories . . . This doctrine is one of the conflict of laws rules applied by American Courts; it is not itself a rule of international law . . . it stems from the concept of the immunity of the sovereign because "the sovereign can do no wrong" (page 855) see also the 3rd Restatement of the Law paragraph 443/444. In International Association of Machinists v. Opec (649F 2d 134) [1981] the 9th circuit Court of Appeals took the matter further

•  "The doctrine of sovereign immunity is similar to the Acts of State Doctrine in that it also represents the need to respect the sovereignty of foreign states. The law of sovereign immunity goes to the jurisdiction of the Court. The Act of State Doctrine is not jurisdictional . . . Rather it is a procedural doctrine designed to avoid action in sensitive areas. Sovereign immunity is a principle of international law, recognised in the United States by statutes. It is the states themselves, as defendants, who may claim sovereign immunity."

    The two doctrines are separate, but they are often run together. The law of Sovereign immunity is now contained in the Foreign Sovereignty Immunities Act (28 USSC-1602) ("F.S.I.A.") in respect of civil matters and many of the decisions on sovereign immunity in the United States turn on the question whether the exemption to a general State immunity from suit falls within one of the specific exemptions. The F.S.I.A. does not deal with criminal Head of State immunity. In the United States the Courts would normally follow a decision of the executive as to the grant or denial of immunity and it is only when the executive does not take a position that "Courts should make an independent determination regarding immunity" (Kravitch S.C.J. in US v. Noriega (7 July 1997)).

    In Kirkpatrick v. Environmental Tectonics (493 U.S. 403 110 S. Ct. 701 (1990)) the Court said that, having begun with comity as the basis for the act of State doctrine, the Court more recently regarded it as springing from the sense that if the judiciary adjudicated on the validity of foreign acts of State, it might hinder the conduct of foreign affairs. The Supreme Court said that "Act of State issues only arise when a Court must decide--that is when the outcome of the case turns upon--the effect of official action by a foreign Sovereign" (p. 705).

    In English law the position is much the same as it was in the earlier statements of the United States Courts. The act of State doctrine "is to the effect that the Courts of one State do not, as a rule, question the validity or legality of the official acts of another Sovereign State or the official or officially avowed acts of its agents, at any rate in so far as those acts involve the exercise of the State's public authority, purport to take effect within the sphere of the latter's own jurisdiction and are not in themselves contrary to international law" (Oppenheim 9th edition, page 365). In Buttes Gas (supra), Lord Wilberforce spoke of the normal meaning of acts of State as being "action taken by a Sovereign State within its own territory." In his speech, only a year before Sabatino, Lord Wilberforce asked whether, apart from cases concerning acts of British officials outside this country and cases concerned with the examination of the applicability of foreign municipal legislation within the territory of a foreign State, there was not "a more general principle that the Courts will not adjudicate upon the transactions of foreign Sovereign States"--a principle to be considered if it existed "not as a variety of 'acts of State', but one of judicial restraint or abstention".

    Despite the divergent views expressed as to what is covered by the Act of State doctrine, in my opinion once it is established that the former Head of State is entitled to immunity from arrest and extradition on the lines I have indicated, United Kingdom Courts will not adjudicate on the facts relied on to ground the arrest, but in Lord Wilberforce's words, they will exercise "judicial restraint or abstention."

    Accordingly, in my opinion, the respondent was entitled to claim immunity as a former Head of State from arrest and extradition proceedings in the United Kingdom in respect of official acts committed by him whilst he was Head of State relating to the charges in the provisional warrant of 22 October 1998. I would accordingly dismiss the appeal.