The rehearing of this appeal has raised a number of separate issues which have been fully considered in the speech of my noble and learned friend Lord Browne-Wilkinson which I have had the benefit of reading in draft. I am in agreement with his reasoning and conclusion that the definition of an "extradition crime" in the Extradition Act 1989 requires the conduct to be criminal under United Kingdom law at the date of commission. I am also in agreement with the analysis and conclusions of my noble and learned friend Lord Hope of Craighead as to the alleged crimes in respect of which Senator Pinochet could be extradited apart from any issue of immunity. I further agree with the view of Lord Browne-Wilkinson that Senator Pinochet is entitled to immunity in respect of charges of murder and conspiracy to murder, but I wish to make some observations on the issue of immunity claimed by Senator Pinochet in respect of charges of torture and conspiracy to torture.
Senator Pinochet ceased to be head of state of Chile on 11 March 1990, and he claims immunity as a former head of state. The distinction between the immunity of a serving head of state and the immunity of a former head of state is discussed by Sir Arthur Watts K.C.M.G., Q.C. in his monograph, "The Legal Position in International Law of Heads of States, Heads of Governments and Foreign Ministers". He states at pp. 53, 88 and 89:
"It is well established that, put broadly, a head of state enjoys a wide immunity from the criminal, civil and administrative jurisdiction of other states. This immunity--to the extent that it exists--becomes effective upon his assumption of office, even in respect of events occurring earlier. . .
"A head of state's immunity is enjoyed in recognition of his very special status as a holder of his state's highest office . . .
"A former head of state is entitled under international law to none of the facilities, immunities and privileges which international law accords to heads of states in office. . .
"After his loss of office he may be sued in relation to his private activities, both those taking place while he was still head of state, as well as those occurring before becoming head of state or since ceasing to be 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. The position is similar to that of acts performed by an ambassador in the exercise of his functions for which immunity continues to subsist even after the ambassador's appointment has come to an end."
Section 20 in Part III of the State Immunity Act 1978 provides that, subject to any necessary modifications, the Diplomatic Privileges Act 1964 shall apply to a sovereign or other head of state, and section 2 of the Act of 1964 provides that the Articles of the Vienna Convention on Diplomatic Relations set out in Schedule 1 to the Act shall have the force of law in the United Kingdom. The Articles set out in Schedule 1 include Articles 29, 31 and 39. Article 29 provides:
"The person of a diplomatic agent shall be inviolable. He shall not be liable to any form of arrest or detention."
Article 31 provides:
"1. A diplomatic agent shall enjoy immunity from the criminal jurisdiction of the receiving state."
Article 39 provides:
"1. Every person entitled to privileges and immunities shall enjoy them from the moment he enters the territory of the receiving state on proceedings to take up his post or, if already in its territory, from the moment when his appointment is notified to the Ministry for Foreign Affairs or such other ministry as may be agreed.
"2. When the functions of a person enjoying privileges and immunities have come to an end, such privileges and immunities shall normally cease at the moment when he leaves the country, or on expiry of a reasonable period in which to do so, but shall subsist until that time, even in case of armed conflict. However, with respect to acts performed by such a person in the exercise of his functions as a member of the mission, immunity shall continue to subsist."
One of the issues raised before your Lordships is whether section 20 of the State Immunity Act relates only to the functions carried out by a foreign head of state when he is present within the United Kingdom, or whether it also applies to his actions in his own state or in another country. Section 20 is a difficult section to construe, but I am of opinion that, with the necessary modifications, the section applies the provisions of the Diplomatic Privileges Act, and therefore the Articles of the Vienna Convention, to the actions of a head of state in his own country or elsewhere, so that, adopting the formulation of Lord Nicholls of Birkenhead in the earlier hearing  3 W.L.R. 1456, 1499E, with the addition of seven words, the effect of section 20 of the Act of 1978, section 2 of the Diplomatic Privileges Act and of the Articles of the Vienna Convention is that:
"a former head of state shall continue to enjoy immunity from the criminal jurisdiction of the United Kingdom with respect to acts performed by him, whether in his own country or elsewhere, in the exercise of his functions as a head of state."
I consider, however, that section 20 did not change the law in relation to the immunity from criminal jurisdiction to which a former head of state was entitled in the United Kingdom but gave statutory form to the relevant principle of international law which was part of the common law.
Therefore the crucial question for decision is whether, if committed, the acts of torture (in which term I include acts of torture and conspiracy to commit torture) alleged against Senator Pinochet were carried out by him in the performance of his functions as head of state. I say "if committed" because it is not the function of your Lordships in this appeal to decide whether there is evidence to substantiate the allegations and Senator Pinochet denies them. Your Lordships had the advantage of very learned and detailed submissions from counsel for the parties and the interveners and from the amicus curiae (to which submissions I would wish to pay tribute) and numerous authorities from many jurisdictions were cited.
It is clear that the acts of torture which Senator Pinochet is alleged to have committed were not acts carried out in his private capacity for his personal gratification. If that had been the case they would have been private acts and it is not disputed that Senator Pinochet, once he had ceased to be head of state, would not be entitled to claim immunity in respect of them. It was submitted on his behalf that the acts of torture were carried out for the purposes of protecting the state and advancing its interests, as Senator Pinochet saw them, and were therefore governmental functions and were accordingly performed as functions of the head of state. It was further submitted that the immunity which Senator Pinochet claimed was the immunity of the state of Chile itself. In the present proceedings Chile intervened on behalf of Senator Pinochet and in paragraph 10 of its written case Chile submitted:
" . . . the immunity of a head of state (or former head of state) is an aspect of state immunity . . . Immunity of a head of state in his public capacity is equated with state immunity in international law . . . Actions against representatives of a foreign government in respect of their governmental or official acts are in substance proceedings against the state which they represent, and the immunity is for the benefit of the state."
Moreover, it was submitted that a number of authorities established that the immunity which a state is entitled to claim in respect of the acts of its former head of state or other public officials applies to acts which are unlawful and criminal.
My Lords, in considering the authorities it is necessary to have regard to a number of matters. First, it is a principle of international law that a state may not be sued in the courts of another state without its consent (although this principle is now subject to exceptions--the exceptions in the law of the United Kingdom being set out in the State Immunity Act 1978). Halsbury's Laws of England 4th ed. published in 1977 vol. 18 para 1548 stated:
"An independent sovereign state may not be sued in the English courts against its will and without its consent. This immunity from the jurisdiction is derived from the rules of international law, which in this respect have become part of the law of England. It is accorded upon the grounds that the exercise of jurisdiction would be incompatible with the dignity and independence of any superior authority enjoyed by every sovereign state. The principle involved is not founded upon any technical rules of law, but upon broad considerations of public policy, international law and comity."
Secondly, many of the authorities cited by counsel were cases where an action in tort for damages was brought against a state. Thirdly, a state is responsible for the actions of its officials carried out in the ostensible performance of their official functions notwithstanding that the acts are performed in excess of their proper functions. Oppenheim's International Law, 9th ed., states at page 545:
"In addition to the international responsibility which a state clearly bears for the official and authorised acts of its administrative officials and members of its armed forces, a state also bears responsibility for internationally injurious acts committed by such persons in the ostensible exercise of their official functions but without that state's command or authorisation, or in excess of their competence according to the internal law of the state, or in mistaken, ill-judged or reckless execution of their official duties. A state's administrative officials and members of its armed forces are under its disciplinary control, and all acts of such persons in the apparent exercise of their official functions or invoking powers appropriate to their official character are prima facie attributable to the state. It is not always easy in practice to draw a clear distinction between unauthorised acts of officials and acts committed by them in their private capacity and for which the state is not directly responsible. With regard to members of armed forces the state will usually be held responsible for their acts if they have been committed in the line of duty, or in the presence of and under the orders of an official superior."
Fourthly, in respect of the jurisdiction of the courts of the United Kingdom, foreign states are now expressly given immunity in civil proceedings (subject to certain express exceptions) by statute. Part I of the State Immunity Act 1978 relating to civil proceedings provides in section 1(1):
"A state is immune from the jurisdiction of the courts of the United Kingdom except as provided in the following provisions of this part of this Act."
But Part I of the Act has no application to criminal jurisdiction and section 16(4) in Part I provides:
"This Part of this Act does not apply to criminal proceedings."
In the United States of America section 1604 of the Foreign Sovereign Immunities Act 1976 provides:
"Subject to existing international agreements to which the United States is a party at the time of enactment of this Act a foreign state shall be immune from the jurisdiction of the courts of the United States and of the states except as provided in sections 1605 to 1607 of this chapter."
Counsel for Senator Pinochet and for Chile relied on the decision of the Court of Appeal in Al-Adsani v. Government of Kuwait (1996) 107 I.L.R. 536 where the plaintiff brought an action for damages in tort against the government of Kuwait claiming that he had been tortured in Kuwait by officials of that government. The Court of Appeal upheld a claim by the government of Kuwait that it was entitled to immunity. Counsel for the plaintiff submitted that the rule of international law prohibiting torture is so fundamental that it is jus cogens which overrides all other principles of international law, including the principle of sovereign immunity. This submission was rejected by the Court of Appeal on the ground that immunity was given by section 1 of the State Immunity Act 1978 and that the immunity was not subject to an overriding qualification in respect of torture or other acts contrary to international law which did not fall within one of the express exceptions contained in the succeeding sections of the Act. Ward L.J. stated at p. 549:
"Unfortunately, the Act is as plain as plain can be. A foreign state enjoys no immunity for acts causing personal injury committed in the United Kingdom and if that is expressly provided for the conclusion is impossible to escape that state immunity is afforded in respect of acts of torture committed outside this jurisdiction."
A similar decision was given by the United States Court of Appeals, Ninth Circuit, in Siderman de Blake v. Republic of Argentina (1992) 965 F.2d 699 where an Argentine family brought an action for damages in tort against Argentina and one of its provinces for acts of torture by military officials. Argentina claimed that it was entitled to immunity under the Foreign Sovereign Immunities Act and the Court of Appeals, with reluctance, upheld this claim. The argument advanced on behalf of the plaintiffs was similar to that advanced in the Al-Adsani case, but the court ruled that it was obliged to reject it because of the express provisions of the Foreign Sovereign Immunities Act, stating at p. 718:
"The Sidermans argue that since sovereign immunity itself is a principle of international law, it is trumped by jus cogens. In short, they argue that when a state violates jus cogens, the cloak of immunity provided by international law falls away, leaving the state amenable to suit.
"As a matter of international law, the Sidermans' argument carries much force.
. . .
"Unfortunately, we do not write on a clean slate. We deal not only with customary international law, but with an affirmative Act of Congress, the FSIA. We must interpret the FSIA through the prism of Amerada Hess. Nothing in the text or legislative history of the FSIA explicitly addresses the effect violations of jus cogens might have on the FSIA's cloak of immunity. Argentina contends that the Supreme Court's statement in Amerada Hess that the FSIA grants immunity 'in those cases involving alleged violations of international law that do not come within one of the FSIA's exceptions', 488 U.S. at 436, 109 S.Ct. at 688, precludes the Sidermans' reliance on jus cogens in this case. Clearly, the FSIA does not specifically provide for an exception to sovereign immunity based on jus cogens. In Amerada Hess, the court had no occasion to consider acts of torture or other violations of the peremptory norms of international law, and such violations admittedly differ in kind from transgressions of jus dispositivum, the norms derived from international agreements or customary international law with which the Amerada Hess court dealt. However, the court was so emphatic in its pronouncement 'that immunity is granted in those cases involving alleged violations of international law that do not come within one of the FSIA's exceptions,' Amerada Hess, 488 U.S. at 436, 109 S. Ct. at 688, and so specific in its formulation and method of approach, id. at 439, 109 S.Ct. at 690 ('Having determined that the FSIA provides the sole basis for obtaining jurisdiction over a foreign state in federal court, we turn to whether any of the exceptions enumerated in the Act apply here'), we conclude that if violations of jus cogens committed outside the United States are to be exceptions to immunity, Congress must make them so. The fact that there has been a violation of jus cogens does not confer jurisdiction under the FSIA."
It has also been decided that where an action for damages in tort is brought against officials of a foreign state for actions carried out by them in ostensible exercise of their governmental functions, they can claim state immunity, notwithstanding that their actions were illegal. The state itself, if sued directly for damages in respect of their actions would be entitled to immunity and this immunity would be impaired if damages were awarded against the officials and then the state was obliged to indemnify them. In Jaffe v. Miller  I.L.R. 446, government officials were sued in tort for laying false criminal charges and for conspiracy for kidnap, and it was held that they were entitled to claim immunity. Finlayson J.A., delivering the judgment of the Ontario Court of Appeal, stated at pp. 458-459:
"I also agree with the reasoning on this issue put forward by counsel for the respondents. Counsel submitted that to confer immunity on a government department of a foreign state but to deny immunity to the functionaries, who in the course of their duties performed the acts, would render the State Immunity Act ineffective. To avoid having its action dismissed on the ground of state immunity, a plaintiff would have only to sue the functionaries who performed the acts. In the event that the plaintiff recovered judgment, the foreign state would have to respond to it by indemnifying its functionaries, thus, through this indirect route, losing the immunity conferred on it by the Act. Counsel submitted that when functionaries are acting within the scope of their official duties, as in the present case, they come within the definition of 'foreign state'."
In my opinion these authorities and similar authorities relating to claims for damages in tort against states and government officials do not support the claim of Senator Pinochet to immunity from criminal proceedings in the United Kingdom because the immunity given by Part I of the State Immunity Act 1978 does not apply to criminal proceedings.
Counsel for Senator Pinochet and for Chile further submitted that under the rules of international law courts recognise the immunity of a former head of state in respect of criminal acts committed by him in the purported exercise of governmental authority. In Marcos and Marcos v. Federal Department of Police (1989) 102 I.L.R. 198 the United States instituted criminal proceedings against Ferdinard Marcos, the former President of the Philippines, and his wife, who had been a Minister in the Philippine Government. They were accused of having abused their positions to acquire for themselves public funds and works of art. The United States authorities sought legal assistance from the Swiss authorities to obtain banking and other documents in order to clarify the nature of certain transactions which were the subject of investigation. Mr. Marcos and his wife claimed immunity as the former leaders of a foreign state. In its judgment the Swiss federal tribunal stated at p. 203:
"The immunity in relation to their functions which the appellants enjoyed therefore subsisted for those criminal acts which were allegedly committed while they were still exercising their powers in the Republic of the Philippines. The proceedings brought against them before the United States courts could therefore only be pursued pursuant to an express waiver by the State of the Philippines of the immunity which public international law grants them not as a personal advantage but for the benefit of the state over which they ruled."
The tribunal then held that the immunity could not be claimed by Mr. & Mrs Marcos in Switzerland because there had been an express waiver by the State of the Philippines. However I would observe that in that case Mr. and Mrs Marcos were not accused of violating a rule of international law which had achieved the status of jus cogens.
Counsel also relied on the decision of the Federal Constitutional Court of the Federal Republic of Germany In re Former Syrian Ambassador to the German Democratic Republic (unreported) 10 June 1997. In that case the former Syrian ambassador to the German Democratic Republic was alleged to have failed to prevent a terrorist group from removing a bag of explosives from the Syrian Embassy, and a few hours later the explosives were used in an attack which left one person dead and more than 20 persons seriously injured. Following German unification and the demise of the German Democratic Republic in 1990 a District Court in Berlin issued an arrest warrant against the former ambassador for complicity in murder and the causing of an explosion. The Provincial Court quashed the warrant but the Court of Appeal overruled the decision of the Provincial Court and restored the validity of the warrant, holding that "The complainant was held to have contributed to the attack by omission. He had done nothing to prevent the explosives stored at the embassy building from being removed." The former ambassador then lodged a constitutional complaint claiming that he was entitled to diplomatic immunity.
The Constitutional Court rejected the complaint and held that the obligation limited to the former German Democratic Republic to recognise the continuing immunity of the complainant, according to Article 39(2) of the Vienna Convention, was not transferred to the Federal Republic of Germany by the international law of state succession.
Counsel for Senator Pinochet and for Chile relied on the following passage in the judgment of the constitutional court:
"For the categorization as an official act, it is irrelevant whether the conduct is legal according to the legal order of the Federal Republic of Germany (see above B.II.2.a)bb)) and whether it fulfilled diplomatic functions in the sense of Article 3 of the VCDR (see also the position taken by the [Swiss] Federal Political Department on 12 May  1961, Schweizerisches Jahrbuch für internationles Recht (SJIR) 21  p. 171; however, a different position was taken by the Federal Political Department on 31 January 1979, reproduced in SJIR 36 (1980), p. 210 at 211 f.). The commission of criminal acts does not simply concern the functions of the mission. If a criminal act was never considered as official, there would be no substance to continuing immunity.
"In addition, there is no relevant customary international law exception from diplomatic immunity here (see Preamble to the VCDR, 5th paragraph) . . . .
"Diplomatic immunity from criminal prosecution basically knows no exception for particularly serious violations of law. The diplomat can in such situations only be declared persona non grata."
However, two further parts of the judgment are to be noted. First, it appears that the explosives were left in the embassy when the ambassador was absent, and his involvement began after the explosives had been left in the embassy. The report states:
"The investigation conducted by the Public Prosecutor's Office concluded that the bombing attack was planned and carried out by a terrorist group. The complainant's sending state had, in a telegram, instructed its embassy in East Berlin to provide every possible assistance to the group. In the middle of August 1983 a member of the terrorist group appeared in the embassy while the complainant was absent and requested permission from the then third secretary to deposit a bag in the embassy. In view of the telegram, which was known to him, the third secretary granted that permission.
"Later, the member of the terrorist group returned to the embassy and asked the third secretary to transport the bag to West Berlin for him in an embassy car. At the same time, he revealed that there were explosives in the bag. The third secretary informed the complainant of the request. The complainant first ordered the third secretary to bring him the telegram, in order to read through the text carefully once again, and then decided that the third secretary could refuse to provide the transportation. After the third secretary had returned and informed the terrorist of this, the terrorist took the bag, left the embassy and conveyed the explosive in an unknown manner towards West Berlin."
It appears that these facts were taken into account by the constitutional court when it stated:
"The complainant acted in the exercise of his official functions as a member of the mission, within the meaning of Article 39(2)(2) of the VCDR, because he is charged with an omission that lay within the sphere of his responsibility as ambassador, and which is to that extent attributable to the sending state.
"The complainant was charged with having done nothing to prevent the return of the explosive. The Court of Appeal derived the relevant obligation of conduct out of the official responsibility of the complainant, as leader of the mission, for objects left in the embassy. After the explosive was left in the embassy and therefore in the complainant's sphere of control and responsibility, he was obligated, within the framework of his official duties, to decide how the explosive would then be dealt with. The complainant made such a decision, apparently on the basis of the telegraphed instruction from his sending state, so that private interests are not discernible (on the classification of activities on the basis of instructions see the Bingham Case in McNair, International Law Opinions, Vol. 1, 1956, p. 196 at 197; Denza, Diplomatic Law, 1976, p. 249 f.; Salmon Manuel de Droit Diplomatique, 1994, p. 458 ff.). Instead, the complainant responded to the third secretary directly, in his position as the superior official, and, according to the view of the Court of Appeal, sought the best solution for the embassy."
In addition the constitutional court stated that the rules of diplomatic law constitute a self-contained regime and drew a distinction between the immunity of a diplomat and the immunity of a head of state or governmental official and stated:
"Article 7 of the Charter of the International Military Tribunal of Nuremberg (UNTS. Vol. 82, p. 279)  and following it Article 7(2) of the Statute of the International Criminal Tribunal for Yugoslavia (ILM 32 (1993), p. 1192), as well as Article 6(2) of the Statute for the International Criminal Tribunal for Rwanda (ILM 33 (1994), p. 1602) state that the official position of an accused, whether as a leader of a state or as a responsible official in a Government department, does not serve to free him from responsibility or mitigate punishment. Exemptions from immunity for cases of war criminals, violations of international law and offences against jus cogens under international law have been discussed as developments of this rule. . . .However, as the wording of Article 7 of the Charter of the International Military Tribunal of Nuremberg makes clear, these exceptions are relevant only to the applicable law of state organs that flows directly from it, in particular for members of the Government, and not to diplomatic immunity.
"State immunity and diplomatic immunity represent two different institutions of international law, each with their own rules, so that no inference can be drawn from any restrictions in one sphere as to possible effects in the other."
Therefore I consider that the passage in the judgment relied on by counsel does not give support to the argument that acts of torture, although criminal, can be regarded as functions of a head of state.
In 1946 the General Assembly of the United Nations affirmed: "The principles of international law recognised by the Charter of the Nuremberg Tribunal and the judgment of the Tribunal" and gave the following directive to its International Law Commission:
"This Committee on the codification of international law established by the resolution of the General Assembly of 11 December 1946, to treat as a matter of primary importance plans for the formulation, in the context of a general codification of offences against the peace and security of mankind, or of an international criminal code, of the principles recognised in the Charter of the Nuremberg Tribunal and in the judgment of the Tribunal."
Pursuant to this directive the 1950 Report of the International Law Commission to the General Assembly set out the following principle followed by the commentary contained in paragraph 103:
"The fact that a person who committed an act which constitutes a crime under international law acted as head of state or responsible Government official does not relieve him from responsibility under international law.
"103. This principle is based on article 7 of the Charter of the Nürnberg Tribunal. According to the Charter and the judgment, the fact that an individual acted as head of state or responsible government official did not relieve him from international responsibility. 'The principle of international law which, under certain circumstances, protects the representatives of a state',said the Tribunal, 'cannot be applied to acts which are condemned as criminal by international law. The authors of these acts cannot shelter themselves behind their official position in order to be freed from punishment . . . .' The same idea was also expressed in the following passage of the findings: 'He who violates the laws of war cannot obtain immunity while acting in pursuance of the authority of the state if the state in authorising action moves outside its competence under international law."
The 1954 International Law Commission draft code of offences against the peace and security of mankind provided in Article III:
"The fact that a person acted as head of state or as responsible Government official does not relieve him of responsibility for committing any of the offences defined in the code."
The Statute of the International Tribunal for the former Yugoslavia established by the Security Council of the United Nations in 1993 for the prosecution of persons responsible for serious violations of international humanitarian law committed in the territory of the former Yugoslavia since 1991 provided in Article 7 paragraph 2:
"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 nor mitigate punishment."
The Statute of the International Tribunal for Rwanda established by the Security Council of the United Nations in 1994 for the prosecution of persons responsible for genocide and other serious violations of international humanitarian law committed in the territory of Rwanda in 1994 provided in Article 6 paragraph 2:
"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 nor mitigate punishment."
The 1996 draft code of the International Law Commission of Crimes against the Peace and Security of Mankind provided in Article 7:
"The official position of an individual who commits a crime against the peace and security of mankind, even if he acted as head of state of Government, does not relieve him of criminal responsibility or mitigate punishment."
In July 1998 in Rome the United Nations Diplomatic Conference of Plenipotentiaries on the Establishment of an International Criminal Court adopted the Statute of the International Criminal Court. The Preamble to the Statute states (inter alia):