He then referred to a number of instruments, including the Charter of the Nuremberg Tribunal (1946), the Charter of the Tokyo Tribunal (1948), the International Law Commission's Draft Code of Crimes Against the Peace and Security of Mankind (provisionally adopted in 1988), and the Statute of the War Crimes Tribunal for former Yugoslavia (1993), all of which expressly provide for the responsibility of heads of state, apart from the Charter of the Tokyo Tribunal which contains a similar provision regarding the official position of the accused. He concluded, at p. 84, that:

 "It can no longer be doubted that as a matter of general customary international law a head of state will personally be liable to be called to account if there is sufficient evidence that he authorised or perpetrated such serious international crimes."

So far as torture is concerned, however, there are two points to be made. The first is that it is evident from this passage that Sir Arthur is referring not just to a specific crime as such, but to a crime which offends against the public order of the international community, for which a head of state may be internationally (his emphasis) accountable. The instruments cited by him show that he is concerned here with crimes against peace, war crimes and crimes against humanity. Originally these were limited to crimes committed in the context of armed conflict, as in the case of the Nuremberg and Tokyo Charters, and still in the case of the Yugoslavia Statute, though there it is provided that the conflict can be international or internal in character. Subsequently, the context has been widened to include (inter alia) torture "when committed as part of a widespread or systematic attack against a civilian population" on specified grounds. A provision to this effect appeared in the International Law Commission's Draft Code of Crimes of 1996 (which was, I understand, provisionally adopted in 1988), and also appeared in the Statute of the International Tribunal for Rwanda (1994), and in the Rome Statute of the International Court (adopted in 1998); and see also the view expressed obiter by the U.S. Court of Appeals in Siderman de Blake v. Republic of Argentina (1992) 965 F. 2d 699 at p. 716. I should add that these developments were foreshadowed in the International Law Commission's Draft Code of Crimes of 1954; but this was not adopted, and there followed a long gap of about 35 years before the developments in the 1990s to which I have referred. It follows that these provisions are not capable of evidencing any settled practice in respect of torture outside the context of armed conflict until well after 1989 which is the latest date with which we are concerned in the present case. The second point is that these instruments are all concerned with international responsibility before international tribunals, and not with the exclusion of state immunity in criminal proceedings before national courts. This supports the conclusion of Lord Slynn ( [1998] 3 W.L.R. 1456 at p. 1474H) that "except in regard to crimes in particular situations before international tribunals these measures did not in general deal with the question whether otherwise existing immunities were taken away", with which I have already expressed my respectful agreement.

It follows that, if state immunity in respect of crimes of torture has been excluded at all in the present case, this can only have been done by the Torture Convention itself.

V. Torture Convention

I turn now to the Torture Convention of 1984, which lies at the heart of the present case. This is concerned with the jurisdiction of national courts, but its "essential purpose" is to ensure that a torturer does not escape the consequences of his act by going to another country: see the Handbook on the Convention by Burgers (the Chairman-Rapporteur of the Convention) and Danelius at p. 131. The Articles of the Convention proceed in a logical order. Article 1 contains a very broad definition of torture. For present purposes, it is important that torture has to be "inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity." Article 2 imposes an obligation on each state party to take effective measures to prevent acts of torture in any territory under its jurisdiction. Article 3 precludes refoulement of persons to another state where there are substantial grounds for believing that he would be in danger of being subjected to torture. Article 4 provides for the criminalisation of torture by each state party. Article 5 is concerned with jurisdiction. Each state party is required to establish its jurisdiction over the offences referred to in Article 4 in the following cases:

 "(a) when the offences are committed in any territory under its jurisdiction . . .;

 (b) when the alleged offender is a national of that state;

 (c) when the victim is a national of that state if that state considers it appropriate"

and also "over such offences in cases where the alleged offender is present in any territory under its jurisdiction and it does not extradite him. . . ."

Article 7 is concerned with the exercise of jurisdiction. Article 7(1) provides:

 "The state party in territory under whose jurisdiction a person alleged to have committed any offence referred to in Article 4 is found, shall in the cases contemplated in Article 5, if it does not extradite him, submit the case to its competent authorities for the purpose of prosecution."

This provision reflects the principle aut dedere aut punire, designed to ensure that torturers do not escape by going to another country.

I wish at this stage to consider briefly the question whether a head of state, if not a public official, is at least a "person acting in a public capacity" within Article 1(1) of the Torture Convention. It was my first reaction that he is not, on the ground that no one would ordinarily describe a head of state such as a monarch or the president of a republic as a "public official", and the subsidiary words "other person acting in a public capacity" appeared to be intended to catch a person who, while not a public official, has fulfilled the role of a public official, for example, on a temporary or ad hoc basis. Miss Montgomery, for Senator Pinochet, submitted that the words were not apt to include a head of state relying in particular on the fact that in a number of earlier conventions heads of state are expressly mentioned in this context in addition to responsible government officials. However, Dr. Collins for the Republic of Chile conceded that, in the Torture Convention, heads of state must be regarded as falling within the category of "other person acting in a public capacity"; and in these circumstances I am content to proceed on that basis. The effect of Dr. Collins' concession is that a head of state could be held responsible for torture committed during his term of office, although (as Dr. Collins submitted) the state of which he was head would be able to invoke the principle of state immunity, ratione personae or materiae, in proceedings brought against him in another national jurisdiction if it thought right to do so. Accordingly, on the argument now under consideration, the crucial question relates to the availability of state immunity.

It is to be observed that no mention is made of state immunity in the Convention. Had it been intended to exclude state immunity, it is reasonable to assume that this would have been the subject either of a separate article, or of a separate paragraph in Article 7, introduced to provide for that particular matter. This would have been consistent with the logical framework of the Convention, under which separate provision is made for each topic, introduced in logical order.

VI. The issue whether immunity ratione materiae has been excluded under the Torture Convention

(a) The argument

I now come to the second of the two issues which were raised during the hearing of the appeal, viz. whether the Torture Convention has the effect that state parties to the Convention have agreed to exclude reliance on state immunity ratione materiae in relation to proceedings brought against their public officials, or other persons acting in an official capacity, in respect of torture contrary to the Convention. In broad terms I understand the argument to be that, since torture contrary to the Convention can only be committed by a public official or other person acting in an official capacity, and since it is in respect of the acts of these very persons that states can assert state immunity ratione materiae, it would be inconsistent with the obligations of state parties under the Convention for them to be able to invoke state immunity ratione materiae in cases of torture contrary to the Convention. In the case of heads of state this objective could be achieved on the basis that torture contrary to the Convention would not be regarded as falling within the functions of a head of state while in office, so that although he would be protected by immunity ratione personae while in office as head of state, no immunity ratione materiae would protect him in respect of allegations of such torture after he ceased to hold office. There can, however, be no doubt that, before the Torture Convention, torture by public officials could be the subject of state immunity. Since therefore exclusion of immunity is said to result from the Torture Convention and there is no express term of the Convention to this effect, the argument has, in my opinion, to be formulated as dependent upon an implied term in the Convention. It is a matter of comment that, for reasons which will appear in a moment, the proposed implied term has not been precisely formulated; it has not therefore been exposed to that valuable discipline which is always required in the case of terms alleged to be implied in ordinary contracts. In any event, this is a different argument from that which was advanced to your Lordships by the appellants and those supporting them, which was that both torture contrary to the Torture Convention, and hostage-taking contrary to the Taking of Hostages Convention, constituted crimes under international law, and that such crimes cannot be part of the functions of a head of state as a matter of international law.

The argument now under consideration was not advanced before the Divisional Court; nor can it have been advanced before the first Appellate Committee, or it would have been considered by both Lord Slynn of Hadley and Lord Lloyd of Berwick in their dissenting opinions. It was not advanced before your Lordships by the appellants and those supporting them, either in their written cases, or in their opening submissions. In fact, it was introduced into the present case as a result of interventions by members of the Appellate Committee in the course of the argument. This they were, of course, fully entitled to do; and subsequently the point was very fairly put both to Miss Montgomery for Senator Pinochet and to Dr. Collins for the Government of Chile. It was subsequently adopted by Mr. Lloyd Jones, the amicus curiae, in his oral submissions to the Committee. The appellants, in their written submissions in reply, restricted themselves to submitting that "The conduct alleged in the present case is not conduct which amounts to official acts performed by the respondent in the exercise of his functions as head of state . . .": see paragraph 11 of their written submissions. They did not at that stage go so far as to submit that any torture contrary to the Torture Convention would not amount to such an official act. However, when he came to make his final oral submissions on behalf of the appellants, Professor Greenwood, following the lead of Mr. Lloyd Jones, and perhaps prompted by observations from the Committee to the effect that this was the main point in the case, went beyond his clients' written submissions in reply and submitted that, when an offence of torture is committed by an official within the meaning of section 134 of the Criminal Justice Act and Article 1 of the Torture Convention, no immunity ratione materiae can attach in respect of that act.

It is surprising that an important argument of this character, if valid, should previously have been overlooked by the fourteen counsel (including three distinguished Professors of International Law) acting for the appellants, and for Amnesty International and Human Rights Watch which are supporting the appellants in this litigation. The concern thereby induced as to the validity of the argument is reinforced by the fact that it receives no support from the literature on the subject and, on the material before your Lordships, appears never to have been advanced before. At all events, having given the matter the most careful consideration, I am satisfied that it must be rejected as contrary to principle and authority, and indeed contrary to common sense.

(b) Waiver of immunity by treaty must be express

On behalf of the Government of Chile Dr. Collins' first submission was that a state's waiver of its immunity by treaty must always be express. With that submission, I agree.

I turn first to Oppenheim's International Law. The question of waiver of state immunity is considered at pp. 351-355 of the 9th edition, from which I quote the following passage:

 "A state, although in principle entitled to immunity, may waive its immunity. It may do so by expressly submitting to the jurisdiction of the court before which it is sued, either by express consent given in the context of a particular dispute which has already arisen, or by consent given in advance in a contract or an international agreement . . . A state may also be considered to have waived its immunity by implication, as by instituting or intervening in proceedings, or taking any steps in the proceedings relating to the merits of the case . . ."

It is significant that, in this passage, the only examples given of implied waiver of immunity relate to actual submission by a state to the jurisdiction of a court or tribunal by instituting or intervening in proceedings, or by taking a step in proceedings.

A similar approach is to be found in the Report of the International Law Commission on the Jurisdictional Immunities of States and their Property reported in 1991 Yb.I.L.C., vol. II, Part 2, in which a fuller exposition of the subject is to be found. Article 7 of the Commission's Draft Articles on this subject is entitled Express consent to exercise of jurisdiction. Article 7(1) provides as follows:

 "1. A state cannot invoke immunity from jurisdiction in a proceeding before a court of another state with regard to a matter or case if it has expressly consented to the exercise of jurisdiction by the court with regard to the matter or case:

  (a) by international agreement;

  (b) in a written contract; or

  (c) by a declaration before the court or by a written communication in a specific proceeding."

I turn to the commentary on Article 7(1), from which I quote paragraph (8) in full:

  "In the circumstances under consideration, that is, in the context of the state against which legal proceedings have been brought, there appear to be several recognisable methods of expressing or signifying consent. In this particular connection, the consent should not be taken for granted, nor readily implied. Any theory of 'implied consent' as a possible exception to the general principles of state immunities outlined in this part should be viewed not as an exception in itself, but rather as an added explanation or justification for an otherwise valid and generally recognised exception. There is therefore no room for implying the consent of an unwilling state which has not expressed its consent in a clear and recognisable manner, including by the means provided in Article 8 [which is concerned with the effect of participation in a proceeding before a court]. It remains to be seen how consent would be given or expressed so as to remove the obligation of the court of another state to refrain from the exercise of its jurisdiction against an equally sovereign state."

The two examples then provided of how such consent would be given or expressed are (i) Consent given in a written contract, or by a declaration or a written communication in a specific proceeding, and (ii) Consent given in advance by international agreement. In respect of the latter, reference is made (in paragraph (10) to such consent being expressed in a provision of a treaty concluded by states; there is no reference to such consent being implied.

The general effect of these passages is that, in a treaty concluded between states, consent by a state party to the exercise of jurisdiction against it must, as Dr. Collins submitted, be express. In general, moreover, implied consent to the exercise of such jurisdiction is to be regarded only as an added explanation or justification for an otherwise valid and recognised exception, of which the only example given is actual submission to the jurisdiction of the courts of another state.

The decision of the Supreme Court of the United States in Argentine Republic v. Amerada Hess Shipping Corporation (1989) 109 S.Ct. 683 is consistent with the foregoing approach. In an action brought by a shipowner against the Argentine Republic for the loss of a ship through an attack by aircraft of the Argentine Air Force, the defendant relied upon state immunity. Among other arguments the plaintiff suggested that the defendant had waived its immunity under certain international agreements to which the United States was party. For this purpose, the plaintiff invoked para. 1605(a)(1) of the Foreign Sovereign Immunities Act 1976, which specifies, as one of a number of exceptions to immunity of foreign states, a case in which the foreign state has waived its immunity either explicitly or by implication. It was the plaintiff's contention that there was an implicit waiver in the relevant international agreements. This submission was tersely rejected by Rehnquist C.J., who delivered the judgment of the court, in the following words, at p. 693:

 "Nor do we see how a foreign state can waive its immunity under para. 1605(a)(1) by signing an international agreement that contains no mention of a waiver of immunity to suit in United States courts . . ."

Once again, the emphasis is on the need for an express waiver of immunity in an international agreement. This cannot be explained away as due to the provisions of the United States Act. On the contrary, the Act contemplates the possibility of waiver by implication; but in the context of a treaty the Supreme Court was only prepared to contemplate express waiver.

I turn next to the State Immunity Act 1978, the provisions of which are also consistent with the principles which I have already described. In Part I of the Act (which does not apply to criminal proceedings--see section 16(4)), it is provided by section 1(1) that "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." For the present purposes, the two relevant provisions are section 2, concerned with submission to the jurisdiction, and section 9, concerned with submissions to arbitration by an agreement in writing. Section 2(2) recognises that a state may submit to the jurisdiction by a prior written agreement, which I read as referring to an express agreement to submit. There is no suggestion in the Act that an implied agreement to submit would be sufficient, except in so far as an actual submission to the jurisdiction of a court of this country, may be regarded as an implied waiver of immunity; but my reading of the Act leads me to understand that such a submission to the jurisdiction is here regarded as an express rather than an implied waiver of immunity or agreement to submit to the jurisdiction. This is consistent with Part III of the Act, which by section 20 provides that, subject to the provisions of that section and to any necessary modifications, the Diplomatic Privileges Act 1964 shall apply to a sovereign or other head of state. Among the Articles of the Vienna Convention on Diplomatic Relations so rendered applicable by section 2 of the Act of 1964 is Article 32 concerned with waiver of immunity, paragraph 2 of which provides that such waiver must always be express, which I read as including an actual submission to the jurisdiction, as well as an express agreement in advance to submit. Once again, there is no provision for an implied agreement.

In the light of the foregoing it appears to me to be clear that, in accordance both with international law, and with the law of this country which on this point reflects international law, a state's waiver of its immunity by treaty must, as Dr. Collins submitted, always be express. Indeed, if this was not so, there could well be international chaos as the courts of different state parties to a treaty reach different conclusions on the question whether a waiver of immunity was to be implied.

(c) The functions of public officials and others acting in an official capacity.

However it is, as I understand it, suggested that this well-established principle can be circumvented in the present case on the basis that it is not proposed that state parties to the Torture Convention have agreed to waive their state immunity in proceedings brought in the states of other parties in respect of allegations of torture within the Convention. It is rather that, for the purposes of the Convention, such torture does not form part of the functions of public officials or others acting in an official capacity including, in particular, a head of state. Moreover since state immunity ratione materiae can only be claimed in respect of acts done by an official in the exercise of his functions as such, it would follow, for example, that the effect is that a former head of state does not enjoy the benefit of immunity ratione materiae in respect of such torture after he has ceased to hold office.

In my opinion, the principle which I have described cannot be circumvented in this way. I observe first that the meaning of the word "functions" as used in this context is well established. The functions of, for example, a head of state are governmental functions, as opposed to private acts; and the fact that the head of state performs an act, other than a private act, which is criminal does not deprive it of its governmental character. This is as true of a serious crime, such as murder or torture, as it is of a lesser crime. As the Lord Chief Justice said in the Divisional Court:

 ". . . a former head of state is clearly entitled to immunity in relation to criminal acts performed in the course of exercising public functions. One cannot therefore hold that any deviation from good democratic practice is outside the pale of immunity. If the former sovereign is immune from process in respect of some crimes, where does one draw the line?"

It was in answer to that question that the appellants advanced the theory that one draws the line at crimes which may be called "international crimes". If, however, a limit is to be placed on governmental functions so as to exclude from them acts of torture within the Torture Convention, this can only be done by means of an implication arising from the Convention itself. Moreover, as I understand it, the only purpose of the proposed implied limitation upon the functions of public officials is to deprive them, or as in the present case a former head of state, of the benefit of state immunity; and in my opinion the policy which requires that such a result can only be achieved in a treaty by express agreement, with the effect that it cannot be so achieved by implication, renders it equally unacceptable that it should be achieved indirectly by means of an implication such as that now proposed.

(d) An implication must in any event be rejected.

In any event, however, even if it were possible for such a result to be achieved by means of an implied term, there are, in my opinion, strong reasons why any such implication should be rejected.

I recognise that a term may be implied into a treaty, if the circumstances are such that "the parties must have intended to contract on the basis of the inclusion in the treaty of a provision whose effect can be stated with reasonable precision"; see Oppenheim's International Law, 9th ed., p. 1271, n.4. It would, however, be wrong to assume that a term may be implied into a treaty on the same basis as a term may be implied into an ordinary commercial contract, for example to give the contract business efficacy (as to which see Treitel on Contract, 9th ed., pp. 185 et seq.). This is because treaties are different in origin, and serve a different purpose. Treaties are the fruit of long negotiation, the purpose being to produce a draft which is acceptable to a number, often a substantial number, of state parties. The negotiation of a treaty may well take a long time, running into years. Draft after draft is produced of individual articles, which are considered in depth by national representatives, and are the subject of detailed comment and consideration. The agreed terms may well be the fruit of "horse-trading" in order to achieve general agreement, and proposed articles may be amended, or even omitted in whole or in part, to accommodate the wishes or anxieties of some of the negotiating parties. In circumstances such as these, it is the text of the treaty itself which provides the only safe guide to its terms, though reference may be made, where appropriate, to the travaux preparatoires. But implied terms cannot, except in the most obvious cases, be relied on as binding the state parties who ultimately sign the treaty, who will in all probability include those who were not involved in the preliminary negotiations.

In this connection, however, I wish first to observe that the assumption underlying the present argument, viz. that the continued availability of state immunity is inconsistent with the obligations of state parties to the Convention, is in my opinion not justified. I have already summarised the principal articles of the Convention; and at this stage I need only refer to Article 7 which requires that a state party under whose jurisdiction a person alleged to have committed torture is found shall, in the cases contemplated in Article 5, if it does not extradite him, submit the case to its competent authorities for the purpose of prosecution. I wish to make certain observations on these provisions. First of all, in the majority of cases which may arise under the Convention, no question of state immunity will arise at all, because the public official concerned is likely to be present in his own country. Even when such a question does arise, there is no reason to assume that state immunity will be asserted by the state of which the alleged torturer is a public official; on the contrary, it is only in unusual cases, such as the present, that this is likely to be done. In any event, however, not only is there no mention of state immunity in the Convention, but in my opinion it is not inconsistent with its express provisions that, if steps are taken to extradite him or to submit his case to the authorities for the purpose of prosecution, the appropriate state should be entitled to assert state immunity. In this connection, I comment that it is not suggested that it is inconsistent with the Convention that immunity ratione personae should be asserted; if so, I find it difficult to see why it should be inconsistent to assert immunity ratione materiae.

The danger of introducing the proposed implied term in the present case is underlined by the fact that there is, as Dr. Collins stressed to your Lordships, nothing in the negotiating history of the Torture Convention which throws any light on the proposed implied term. Certainly the travaux preparatoires shown to your Lordships reveal no trace of any consideration being given to waiver of state immunity. They do however show that work on the draft Convention was on foot as long ago as 1979, five years before the date of the Convention itself. It is surely most unlikely that during the years in which the draft was under consideration no thought was given to the possibility of the state parties to the Convention waiving state immunity. Furthermore, if agreement had been reached that there should be such a waiver, express provision would inevitably have been made in the Convention to that effect. Plainly, however, no such agreement was reached. There may have been recognition at an early stage that so many states would not be prepared to waive their immunity that the matter was not worth pursuing; if so, this could explain why the topic does not surface in the travaux preparatoires. In this connection it must not be overlooked that there are many reasons why states, although recognising that in certain circumstances jurisdiction should be vested in another national court in respect of acts of torture committed by public officials within their own jurisdiction, may nevertheless have considered it imperative that they should be able, if necessary, to assert state immunity. The Torture Convention applies not only to a series of acts of systematic torture, but to the commission of, even acquiescence in, a single act of physical or mental torture. Extradition can nowadays be sought, in some parts of the world, on the basis of a simple allegation unsupported by prima facie evidence. In certain circumstances torture may, for compelling political reasons, be the subject of an amnesty, or some other form of settlement, in the state where it has been, or is alleged to have been, committed.

Furthermore, if immunity ratione materiae was excluded, former heads of state and senior public officials would have to think twice about travelling abroad, for fear of being the subject of unfounded allegations emanating from states of a different political persuasion. In this connection, it is a mistake to assume that state parties to the Convention would only wish to preserve state immunity in cases of torture in order to shield public officials guilty of torture from prosecution elsewhere in the world. Such an assumption is based on a misunderstanding of the nature and function of state immunity, which is a rule of international law restraining one sovereign state from sitting in judgment on the sovereign behaviour of another. As Lord Wilbeforce said in I Congreso del Partido [1983] 1 A.C. 244, 272, "The whole purpose of the doctrine of state immunity is to prevent such issues being canvassed in the courts of one state as to the acts of another." State immunity ratione materiae operates therefore to protect former heads of state, and (where immunity is asserted) public officials, even minor public officials, from legal process in foreign countries in respect of acts done in the exercise of their functions as such, including accusation and arrest in respect of alleged crimes. It can therefore be effective to preclude any such process in respect of alleged crimes, including allegations which are misguided or even malicious--a matter which can be of great significance where, for example, a former head of state is concerned and political passions are aroused. Preservation of state immunity is therefore a matter of particular importance to powerful countries whose heads of state perform an executive role, and who may therefore be regarded as possible targets by governments of states which, for deeply felt political reasons, deplore their actions while in office. But, to bring the matter nearer home, we must not overlook the fact that it is not only in the United States of America that a substantial body of opinion supports the campaign of the I.R.A. to overthrow the democratic government of Northern Ireland. It is not beyond the bounds of possibility that a state whose government is imbued with this opinion might seek to extradite from a third country, where he or she happens to be, a responsible Minister of the Crown, or even a more humble public official such as a police inspector, on the ground that he or she has acquiesced in a single act of physical or mental torture in Northern Ireland. The well-known case of The Republic of Ireland v. The United Kingdom (1978) 2 E.H.R.R. 25 provides an indication of circumstances in which this might come about.

Reasons such as these may well have persuaded possible state parties to the Torture Convention that it would be unwise to give up the valuable protection afforded by state immunity. Indeed, it would be strange if state parties had given up the immunity ratione materiae of a head of state which is regarded as an essential support for his immunity ratione personae. In the result, the subject of waiver of state immunity could well not have been pursued, on the basis that to press for its adoption would only imperil the very substantial advantages which could be achieved by the Convention even if no waiver of state immunity was included in it. As I have already explained, in cases arising under the Convention, state immunity can only be relevant in a limited number of cases. This is because the offence is normally committed in the state to which the official belongs. There he is unprotected by immunity, and under the Convention the state has simply to submit the case to the competent authorities. In practice state immunity is relevant in only two cases--where the offender is present in a third state, or where the offender is present in a state one of whose nationals was the victim, that state being different from the state where the offence was committed. A case such as the present must be regarded as most unusual. Having regard to considerations such as these, not to press for exclusion of state immunity as a provision of the Convention must have appeared to be a relatively small price to pay for the major achievement of widespread agreement among states (your Lordships were informed that 116 states had signed the Convention) in respect of all the other benefits which the Convention conferred. After all, even where it was possible for a state to assert state immunity, in many cases it would not wish to expose itself to the opprobrium which such a course would provoke; and in such cases considerable diplomatic or moral pressure could be exerted upon it to desist.

I wish to stress the implications of the fact that there is no trace in the travaux preparatoires of any intention in the Convention to exclude state immunity. It must follow, if the present argument is correct, first that it was so obvious that it was the intention that immunity should be excluded that a term could be implied in the Convention to that effect, and second that, despite that fact, during the negotiating process none of the states involved thought it right to raise the matter for discussion. This is remarkable. Moreover, it would have been the duty of the responsible senior civil servants in the various states concerned to draw the attention of their Governments to the consequences of this obvious implication, so that they could decide whether to sign a Convention in this form. Yet nothing appears to have happened. There is no evidence of any question being raised, still less of any protest being made, by a single state party. The conclusion follows either that every state party was content without question that state immunity should be excluded sub silentio, or that the responsible civil servants in all these states, including the United Kingdom, failed in their duty to draw this very important matter to the attention of their Governments. It is difficult to imagine that either of these propositions can be correct. In particular it cannot, I suspect, have crossed the minds of the responsible civil servants that state immunity was excluded sub silentio in the Convention.

The cumulative effect of all these considerations is, in my opinion, to demonstrate the grave difficulty of recognising an implied term, whatever its form, on the basis that it must have been agreed by all the state parties to the Convention that state immunity should be excluded. In this connection it is particularly striking that, in the Handbook on the Torture Convention by Burgers and Danelius, it is recognised that the obligation of a state party, under Article 5(1) of the Convention, to establish jurisdiction over offences of torture committed within its territory, is subject to an exception in the case of those benefiting from special immunities, including foreign diplomats. It is true that this statement could in theory be read as limited to immunity ratione personae; but in the absence of explanation it should surely be read in the ordinary way as applicable both to immunity ratione personae and its concomitant immunity ratione materiae, and in any event the total silence in this passage on the subject of waiver makes it highly improbable that there was any intention that immunity ratione materiae should be regarded as having been implicitly excluded by the Convention. Had there been such an intention, the authors would have been bound to refer to it. They do not do so.