(i)  In general

An associated question is whether the mere enactment of legislation can give rise to international responsibility, or whether an obligation is only breached when the state implements that legislation. There is a general duty to bring national law into conformity with obligations under international law,27 but what this entails depends on the obligation in question. Normally a failure to bring about such conformity is not in itself a breach of international law; that arises only when the state concerned fails to observe its obligations on a specific occasion.28 But in some circumstances legislation (in its absence) could of itself constitute a breach of an international obligation, for example where a state is required to prohibit certain conduct or to enact a uniform law.

(ii)  National laws as ‘facts’ before international tribunals

Thus a decision of a national court or a legislative measure may constitute evidence of a breach of a treaty or of customary international law.30 However, the general proposition that international tribunals take account of national laws only as facts ‘is, at most…debatable’.31

The concept of national law as ‘merely facts’ has at least six distinct aspects.

1. 
   

   (a)  National law may itself constitute, or be evidence of, conduct in violation of a rule of treaty or customary law.

   
   
2. 
   

   (b)  National law may be part of the ‘applicable law’ either governing the basis of a claim or more commonly governing a particular issue.

   
   
3. 
   

   (c)  Whereas the principle iura novit curiaapplies to international law, it does not apply to matters of national law. International tribunals will generally require proof ofReferences(p. 53) national law, although they may also (subject to due process constraints) undertake their own researches.32

   
   
4. 
   

   (d)  When called upon to apply national law an international tribunal should seek to apply that law as it would be applied in the state concerned.33It is for each state, in the first instance, to interpret its own laws.34International tribunals are not courts of appeal and they do not have the authority to substitute their own interpretation of national law for those of the national authorities, especially when that interpretation is given by the highest national courts. In many situations an international tribunal must simply take note of the outcome of a domestic decision and then deal with its international implications.35It will only be in exceptional circumstances that an international tribunal will depart from the construction adopted by a national authority of its own law, such as where a manifestly incorrect interpretation is put forward in the context of a pending case.36

   
   
5. 
   

   (e)  International tribunals cannot declare the unconstitutionality or invalidity of rules of national law as such.37Only if it is transparently clear that a national law would be treated as unconstitutional or invalid by the national courts should an international tribunal follow suit.

   
   
6. 
   

   (f)  The proposition that an international tribunal ‘does not interpret national law as such’38is open to question. When it is called on to apply rules of national law, an international tribunal will interpret and apply domestic rules as such.39This may occur in a variety of circumstances. First there is the case of renvoi: in Lighthouses, for example, the special agreement required the court to decide if the contracts had been ‘duly entered into’ under Ottoman law.40Or international law may designate a system of domesticReferences(p. 54) law as the applicable law in respect of some claim or transaction.41Where relevant issues (whether classified as ‘facts’ or otherwise) require investigation of national law, the Court has made the necessary findings.

(iii)  Treatment of national law by international tribunals

Cases where a tribunal dealing with issues of international law has to examine the national law of one or more states are by no means exceptional.42 The spheres of competence claimed by states, represented by territory, jurisdiction, and nationality of individuals and legal persons, are delimited by legislation and judicial and administrative decisions. International law sets the limits of such competence, but in order to decide whether particular acts are in breach of obligations under treaties or customary law, the Court has had to examine national law relating to a wide range of topics including expropriation,43 fishing limits,44 nationality,45guardianship and welfare of infants,46 the rights of shareholders in respect of damage suffered by corporations,47 and the arbitrary arrest and expulsion of aliens.48 National law is very frequently implicated in cases concerning individuals, including those relating to the protection of human rights and the exhaustion of local remedies.

A considerable number of treaties contain provisions referring directly to national law49 or employing concepts which by implication are to be understood in the context of a particular national law.50 Many treaties refer to ‘nationals’ of the contracting parties,51 and the presumption is that the term connotes persons having that status under the internal law of one of the parties. Similarly, treaties often involve references to legal interests of individuals and corporations existing within the cadre of a given national law. Treaties having as their object the creation and maintenance of certain standards of treatment of minority groups or aliens may refer to a national law as a method of describing the status to be created and protected.52 The protection of rights may be stipulated as being ‘without discrimination’ or as ‘national treatment’ for theReferences(p. 55) categories concerned.53 Controversy has been generated in relation to the meaning and scope of the so-called ‘umbrella clause’54 including the circumstances in which breach of a contract between an investor and a host state will also amount to a breach of such a clause contained in an investment treaty.55 The better view is that, if the obligation in question is one which arises under national law, for example under a contract, it is only if in truth the obligation is breached that the umbrella clause has anything to operate upon: that clause does not ‘internationalize’ the contract.56

On occasion an international tribunal may be faced with the task of deciding issues solely on the basis of national law. Serbian Loans57 concerned a dispute between the French bondholders of certain Serbian loans and the Serb-Croat-Slovene government, the former demanding loan service on a gold basis, the latter holding that payment in French paper currency was permissible. The French government took up the case of the French bondholders and the dispute was submitted to the Permanent Court. The Court emphasized its duty to exercise jurisdiction duly conferred by agreement, in the absence of provision to the contrary in the Statute.58On the merits the Court held that the substance of the debt and the validity of the clause defining the obligation of the debtor state were governed by Serbian law, but, with respect to the method of payment, the law applicable was that of the place of payment, in this case French law.

(i)  Establishing international law before national courts

An initial issue is whether the jurisdiction considers international law to be ‘part of ’ (in the sense of generally available to) national law, a question that is oft en constitutional in character, and which may be answered differently for customary law andReferences(p. 56) treaties.59 Thus, the 1949 German Grundgesetz provides in Article 25 that ‘[t]he general rules of public international law shall be an integral part of federal law’. Where such a position is adopted, a national court will go about establishing the content of international law as a matter of legal argument.60 Once a court has ascertained that there are no bars within its own legal system to applying the rules of international law or provisions of a treaty, the rules are accepted as rules of law and are not required to be established by evidence, as in the case of matters of fact and foreign law.61 But in the case of international law, this process of judicial notice has a special character. In the first place, there is a serious problem involved in finding reliable information of international law, especially customary law, in the absence of formal proof and resort to expert witnesses. Secondly, issues of public policy and difficulties of obtaining evidence on larger issues of state relations combine to produce a procedure whereby the executive may be consulted on certain questions of mixed law and fact, for example, the existence of a state of war or the status of an entity claiming sovereign immunity.

Thus in France, for example, the Minister of Foreign Affairs may give an interpretation of a treaty to a court, which may then be relied upon in later cases involving the same provision.62 Detailed research is normally out of the question, and counsel cannot always fill the gap. In these circumstances it is hardly surprising that courts have historically leaned heavily on the opinions of writers, though modern practice—at least in England—has tended to steer away from academic commentaries as a source of law.63 It can happen that a national court itself makes a full investigation of all the legal sources,64 including treaties and state practice—yet here also works of authority may be relied upon as repositories and assessors of state practice. Reference may also be made to decisions of international tribunals65 and the work of the ILC.66

References(p. 57) (ii)  International law as the applicable law in national courts

Once a national court has determined that international law is in some way applicable to a matter before it, it falls to the court to determine how that law is to sit alongside any national law that may also be applicable. Indeed, the increasing penetration of international law into the domestic sphere has to an extent muddied the distinction between the two.67 Thus, international law is increasingly finding its way into national courts, and judges are increasingly finding themselves called upon to interpret and apply it—or at least to be aware of its implications.

Again, the approach of a national court to international law will be largely determined by the rules of the jurisdiction in question. But certain issues common to many or all jurisdictions may be identified.

1. 
   

   (a)  Courts may be called upon to adjudicate in conflicts between a municipal law on the one hand, and a rule of customary international law on the other. Many municipal systems now appear to have in one way or another accepted customary international law as ‘the law of the land’, even where no constitutional provision is made,68but questions remain as to how it fits within the internal hierarchy of a national system. As a general (but by no means absolute) rule, an extant statute will prevail over a rule of customary international law if no reconciliation is possible by way of interpretation.69

   
   
2. 
   

   (b)  The question also arises with respect to treaties, but will take on a more overtly constitutional flavour. ‘Monist’ systems may expressly provide that duly signed and ratified treaties take precedence over national legislation.70In other (‘dualist’) systems where the conclusion of a treaty is an executive act, it will be for the legislature to implement the treaty as part of domestic law—insofar as this may be required. In such a system the treaty is applied by the courts as mediated by the legislation, and legislation will prevail, again unless the issue can be resolved by interpretation.71

   
   
3. 
   

   (c)  When applying international law rules, municipal courts may find it necessary to develop the law, notably where it is unclear or uncertain.72This will include consideration of how the international rule is applicable in a domestic context, a processReferences(p. 58) which has been notable, for example, in the field of state immunity.73The question is particularly vexed in the US due to the so far unique provisions of the Alien Tort Statute74and subsequent efforts to define its scope.75

   
   
4. 
   

   (d)  Even in monist systems, the court may need to determine the extent to which a rule of international law may be directly applied. For example, a treaty (even if duly ratified and approved in accordance with constitutional processes) may be held ‘non-self-executing’, that is to say, inapplicable without further specification or definition by the legislature.76

   
   
5. 
   

   (e)  A further question is the extent to which the executive may intervene in the court’s application of international law. One consideration may be the need for the judiciary and the executive to speak with one voice with respect to the foreign policy of the country in question. Thus, when considering issues such as the recognition of states and governments, state immunity and diplomatic immunity the courts may accept direction from the executive.77Caution must be exercised, however, particularly in the European context, with the European Court of Human Rights holding in Beaumartin v France that the practice in extreme forms is incompatible with the right of access to ‘an independent and impartial tribunal’.78There, the practice scrutinized was the French procedure of referring preliminary questions on matters of treaty interpretation to the Minister for Foreign Affairs, and treating any opinion given as binding.79The revised French practice does not attribute binding effect to such opinions and indeed does not require them to be given at all.80

   
   
6. 
   

   (f)  A court may be called upon under the rules of private international law to apply foreign law. If it is alleged that the applicable law is in conflict with international law, the court may be required to determine whether the act or law of a foreign state is contrary to its international obligations. In many jurisdictions—notably in the US—such issues have given rise to the ‘act of state’ doctrine, whereby a court will, as an organ of a sovereign, refuse to pass judgment on the acts of another, formally equal, sovereign. The scope of the doctrine varies from one jurisdiction to another.

   
   
7. 
   

   References(p. 59) (g)  Finally, the court, confronted with an intricate issue of international law, may simply concede that it is beyond its capacity to decide, that is, is non-justiciable. As will be seen, the doctrine exists in England and in other common law jurisdictions.81

A further suite of issues emerges with respect to federal states:82 the capacity of entities other than the federal government to deal with questions of foreign affairs; the place of international law in the components of the federal system,83 and the capacity of courts other than those at a federal level to apply international law.

(i)  National res iudicata before international courts

From a formal point of view, res iudicata is a general principle within the meaning of Article 38(1)(c) of the Statute, applied in tandem by international and national courts.85 But there is no effect of res iudicata from the decision of a national court so far as an international jurisdiction is concerned. Even if the subject-matter may be substantially the same, the parties may well not be, at least in the context of diplomatic protection and possibly outside that context also.86 Other considerations also play a role, not least the principle that international law is (in its own terms) supreme. But an international tribunal may be bound by its constituent instrument to accept certain categories of national decisions as conclusive of particular issues.87

Some international tribunals afford natural and juridical persons standing against states, including decisions of state courts. For example the European Court of HumanReferences(p. 60) Rights functions as a court of final resort on human rights issues; it is only accessible once local remedies have been exhausted and does not re-examine any questions of fact already dealt with by a municipal court.88 In the case of investor-state arbitration tribunals, the default position is that the decisions of national court create no res iudicata insofar as the work of the tribunal is concerned,89 but the parties to the bilateral or multilateral treaty granting the tribunal jurisdiction may incorporate procedural roadblocks into the bargain, such as the so-called ‘fork in the road’ clause.90 Such a clause requires the claimant to elect investor-state arbitration or litigation before the courts of the host state of the investment as its preferred method of dispute resolution. Once an election is made, other ways of bringing the original claim are closed to the claimant.

(ii)  International res iudicata before national courts

In principle decisions by organs of international organizations are not binding on national courts without the co-operation of the national legal system,91 which may adopt a broad constitutional provision for ‘automatic’ incorporation of treaty norms or require specific acts of incorporation or implementation. On the other side of the equation, however, municipal courts may seek to circumvent the finality of such decisions without engaging the question of res iudicata through interpretive legerdemain. In recent times this has been a feature of US practice, which links the effect of a judgment to the status of the relevant international court or tribunal’s constitutive instrument within municipal law.92

Leaving aside such arguments, a decision of the International Court, even one concerning substantially the same issues as those before a national court, does not of itself create a res iudicata for the latter.93 However, it does not follow that a national court should not recognize the validity of the judgment of an international tribunal of manifest competence and authority, at least for certain purposes.94 For this reason, states oft en accord res iudicata effect to international and domestic arbitral awards.95 On the one hand, this is desirable as a matter of common sense, and the argumentsReferences(p. 61) from a policy perspective are well known; parties to litigation are at a certain point in time entitled to draw a line under a dispute and be free of continued legal harassment. On the other, it may be the subject of a treaty obligation, for example under the New York Convention96 or the ICSID Convention.97 Outside those areas with specific treaty obligations, state practice is extremely variable, with a number of countries not affording res iudicata effect to foreign judgments,98 or even those judgments arising from a different federal unit of the same country.99

(iii)  Res iudicata and third parties

In international law res iudicata includes issue estoppel, but does not extend to the US doctrine of collateral estoppel (binding upon third parties).100 But the decisions of an international court or tribunal may carry evidentiary weight even vis-à-vis third parties. For example national courts, in dealing with cases of war crimes and issues arising from belligerent occupation, the validity of acts of administration, of requisition and of transactions conducted in occupation currency have relied upon the findings of the International Military Tribunals at Nuremberg and Tokyo as evidence, even conclusive evidence, of the illegality of the war which resulted in the occupations.101

Quite aside from this, the legal reasoning employed by international tribunals may carry weight. In Mara’abe v Prime Minister of Israel, the Supreme Court of Israel found that the International Court’s Wall advisory opinion102 did not constitute res iudicata but that the Court’s interpretation of international law (as opposed to factual determinations) should be given ‘full appropriate weight’.103

(i)  Unincorporated treaties

In England the conclusion and ratification of treaties are within the prerogative of the Crown, and if a transformation doctrine were not applied, the Crown could legislate for the subject without parliamentary consent,110 in violation of the basal notion of parliamentary sovereignty.111 The rule does not apply in the very rare cases where the Crown’s prerogative can directly extend or contract jurisdiction without the need for legislation.112

(ii)  Incorporated treaties

Once a treaty is implemented by Parliament,118 the resulting legislation forms part of UK law and is applicable by the courts as so implemented.119 Accordingly, there is no distinction in the law of the UK between self-executing and non-self-executing treaties; all treaties may be classified as non-self-executing as all require legislative action to become law. An apparent exception to this rule arises in the case of treaties concluded by the institutions of the European Union, with the European Court of Justice holding these to be directly enforceable within member states as part of the acquis communautaire. But in UK law EU treaties have this effect because of the relevant statute.120

Once enacted, the statute implementing the treaty will function as any other Act of Parliament. Thus, for example, the words of a subsequent Act of Parliament will prevail over the provisions of a prior treaty in case of clear inconsistency between the two.121

References(p. 65) Legislation to give effect in domestic law to treaty provisions may take various forms. A statute may directly enact the provisions of the international instrument, which will be set out as a schedule to the Act.122 It may employ its own substantive provisions to give effect to a treaty, the text of which is not itself enacted. It may be that the enacting legislation makes no specific reference to the treaty in question, though there is extrinsic evidence to show that the statute was intended to give effect to it.123 The result is a balancing act that requires the court to scrutinize the strength of the relationship between the enacting statute and its parent treaty, and determines the124 strength of the latter as an interpretative tool.

(iii)  Treaties and the interpretation of statutes125

Questions surrounding the interpretation of treaties and statutes in English law can generally be divided into two categories: the interpretation of enabling instruments, and the interpretation of other legislation in light of treaties entered into, both incorporated and unincorporated. As to the former, it is to be remembered that primary object of interpretation is the implementing statute, and only at one remove the treaty which implements or incorporates it.126 Accordingly, although international courts and tribunals may rule on the interpretation of a treaty, their rulings are not binding.127

On the other hand the interpretation of treaty provisions is a matter of law. Unlike in some countries, the courts do not seek binding interpretations of treaties from the executive.128 They will apply international rules of treaty interpretation, as reflected in the Vienna Convention on the Law of Treaties,129 rather than the domestic canons of statutory interpretation (though these are less different than they were).130 Furthermore,References(p. 66) in the interests of coherent interpretation between states parties to the relevant agreement, the decisions of other domestic tribunals on the interpretation of treaties are taken into account.131

Difficulties may arise where the implementing statute is ambiguous on its face as to the extent to which it implements a treaty, or fails to mention the treaty entirely. But where it is clear that Parliament intended to implement a treaty through the legislation, the terms of the legislation are to be construed if possible so as to conform to the treaty.132

More generally, as noted by Diplock LJ in Salomon: ‘Parliament does not intend to act in breach of international law, including therein specific treaty obligations’.133 This presumption applies to unincorporated treaties as much as incorporated ones,134 but it only applies to legislation enacted after a treaty has been signed or ratified.135 On the other hand, it will apply even where there is no link between the treaty and the legislation in question.136 In addition to legislation, the presumption may also apply to other instruments or guidelines given domestic effect.137

References(p. 67) (iv)  Treaties and the determination of the common law

The presumption in favour of interpreting English law in a way which does not place the UK in breach of an international obligation applies not only to statutes but also to the common law.140 Use may be made of unincorporated treaties particularly where the common law is uncertain or developing.141 The English courts have regularly taken into account treaty-based standards concerning human rights in order to resolve issues of common law, including the legality of telephone tapping,142 the offence of criminal libel,143 contempt of court,144and freedom of association.145 This development is not confined to human rights treaties: Alcom Ltd v Republic of Colombia, for example, involved reference to general international law for purposes of statutory interpretation in the context of state immunity.146

(i)  ‘Incorporation’

References(p. 68) But according to Lord Wilberforce, it may be wise to ‘avoid commitment to more of the admired judgment of Lord Denning MR than is necessary’.150 The position in England is not that custom forms part of the common law (how can foreign states of whatever legal tradition make the common law?), but that it is a source of English law that the courts may draw upon as required.151 The doctrine is decisive only occasionally. According to O’Keefe, outside of immunities cases it has only twice had a decisive impact on the outcome,152 although there are other cases where it has been influential.

In short, the relationship of custom and the common law is more nuanced than either the doctrines of incorporation or transformation would suggest.154

(ii)  The process and limits of ‘incorporation’

It is possible to discern a broad process in the way the common law adopts customary international law. There is an initial question of or akin to choice of law: is this a subject matter on which international law has something to say, and which it allows (or even requires) national courts to say. If (as with foreign state immunity) the answer to both questions is yes, there is a second, constitutional question: is this an area where the common law courts retain law-making power or (as with substantive criminal law) not.155 Where it is appropriate to consider norms of international law, rather than the law of the forum or a foreign law, then the courts will take judicial notice of the applicable rules, whereas formal evidence is required of foreign (national) law.

References(p. 69) However, the courts still have to ascertain the existence of the rules of international law and their effect within the national sphere: the latter task is a matter on which the rules of international law may provide limited guidance. Case-law suggests that four considerations are relevant to the question of incorporation.156

1. 
   
   (a)  The first question is whether the customary international law rule is susceptible to domestic application.157For example, is the rule in question of a strictly interstate character, or does it implicate the rights of private parties? Self-evidently, the former may be difficult to restructure as a norm within a domestic legal system, aside from cases where the common law has transposed the various state immunities directly from international law. In the case of the latter, individual rights may be more readily transposed.158Some courts have identified further limits that might be imposed on such an attempted transposition, based not on amenability for adoption, but on the character of the norm. In Al-Saadoon, Laws LJ said:
   

   
   

   
   

   [T]he…proposition that the customary rule may be sued as a cause of action in the English courts is perhaps not so clear cut. It would of course have to be shown that the rule did not conflict with any provision of English domestic law…I apprehend the rule would also have to possess the status of jus cogens erga omnes…159

   
   

   But whilst ‘incorporation’ as conceived here has existed since the eighteenth century, the concept of peremptory norms is much more recent. The combination of the two is ahistorical—but the insight that certain norms may imperatively call for implementation is a valuable one. Something similar may have been implied by Justice Souter’s dictum for the Supreme Court in Sosa that norms of international law, to be given direct effect under the Alien Tort Statute, have to be ‘specific, universal, and obliga tory’ (although Sosa concerned statutory, not common law incorporation).160

   
   
2. 
   

   (b)  The next question is whether the proposed common law rule is contradicted by any constitutional principle.161Thus in R v Jones (Margaret), the issue was whether the crime of aggression in customary international law could be considered part of the law of England. Lord Bingham said that in order for a customary norm to be translated to the common law, it must conform to the constitution: ‘customary internationalReferences(p. 70) law is applicable in the English courts only where the constitution permits’.162As the constitution requires that only Parliament could be responsible for the creation of crimes in English law,163aggression could not be considered an element of the common law but was a matter for legislation.164Lords Hoffmann and Mance reached substantially similar conclusions.165

   
   
   Within the consideration of constitutionality and custom is the principle that the common law is inferior to statute, a concept flowing directly from the doctrine of parliamentary sovereignty.166Thus, a customary norm may only be transposed into the common law to the extent that it does not conflict with an Act of Parliament. In Chung Chi Cheung v R, Lord Atkin said:167
   

   
   

   
   

   The courts acknowledge the existence of a body of rules which nations accept amongst themselves. On any judicial issue, they seek to ascertain the relevant rule, and, having found it, they will treat it as incorporated into the domestic law, so far as it is not inconsistent with rules enacted by statutes or finally declared by their tribunals.

   
   

   Thus, in Ex parte Thakrar, a statement in the Immigration Act 1979 that any exceptions to the rule that a non-patrial required leave to enter the UK were to be found within the Act itself prevented the introduction of an additional exception through the operation of customary international law.168Similarly, in Al-Adsani v Government of Kuwait, Mantell J would not accept the argument that a common law tort of ‘torture’ arising from custom (even if it could be said that one existed) would prevail over the provisions of the State Immunity Act 1978.169

   
   
3. 
   

   (c)  A third consideration is whether the proposed rule is itself contradicted by some antecedent principle of the common law. In West Rand, Lord Alverstone CJ accepted that custom could contribute to the common law insofar as it was not ‘contrary to the principles of her laws as decided by her courts’.170Similarly, Lord Atkin in Chung Chi Cheung v R conditioned incorporation on consistency ‘with rules…finallyReferences(p. 71) declared by…tribunals’.171A practical example of how extant principles may bar the expansion of the common law in this way occurred in Chagos Islanders v Attorney General.172The case concerned a claim for damages based in reliance on the UK’s supposed breach of the international human right not to be prevented from returning to one’s home state. Ouseley J denied the claim, noting that even if breach of the right in question could be said to violate a common law as well as customary right, this could not, in itself, give rise to an action for damages. To do so, His Honour noted, would be ‘no more and no less than a particular example of a tort for unlawful administrative acts’,173the possibility of which the House of Lords had previously excluded at common law.174

   
   
4. 
   
   (d)  A further problem is one of precedent. In Trendtex, Lord Denning said:
   

   
   

   
   

   International law knows no rule of stare decisis. If this court is satisfied that the rule of international law on a subject has changed from what it was 50 or 60 years ago, it can give effect to that change—and apply the change in our English law— without waiting for the House of Lords to do it…After all, we are not considering here the rules of English law on which the House has the final say. We are considering the rules of international law.175

   
   
   By contrast in Thai-Europe Tapioca Service Ltd v Government of Pakistan Scarman LJ said:
   

   
   

   
   

   it is important to realise that a rule of international law, once incorporated into our law by decisions of a competent court, is not an inference of fact but a rule of law. It therefore becomes part of our municipal law and the doctrine of stare decisisapplies as much to that as to a rule of law with a strictly municipal provenance.176

But it is excessively parochial to think that an incorporated rule of international law is entirely domesticated, any more than an incorporated treaty. It should be open to the courts to reconsider the rule if there are indications of material change in international law, and more generally to track developments in the law. On the one hand it was artificial to think that a House of Lords decision on absolute immunity of 1938177 should be considered as preclusive in the very different state of affairs in 1978. On the other hand the decision in Trendtex was authority on the contemporary state of international law, and was in fact followed as such.178

(i)  Non-justiciability

It was a long-standing position in English law that the Crown’s prerogative powers were immune from judicial control. That is no longer so,179 although the extent of judicial review depends on the subject-matter.180

Despite these developments, several areas of government activity connected with international law remain generally off limits to the courts. In Abassi the Court of Appeal was asked to require the Foreign Secretary to make representations to the US government on behalf of British nationals detained in Guantanamo Bay. Although the Court was deeply concerned by what it saw as US intransigence, it declined to make the orders requested.181

The courts are also extremely reluctant to pronounce on issues connected to the deployment of armed forces.182 In R v Jones (Margaret), Lord Hoffmann acknowledged that whilst the House of Lords was in principle capable of examining the deployment of armed forces by the government, ‘[t]he decision to go to war, whether one thinks it was right or wrong, fell squarely within the discretionary powers of the Crown to defend the realm and conduct its foreign affairs’.183

Similarly, in Al-Jedda,190 the claimant alleged that his detention in Iraq by British forces was in breach of the UK’s obligations under the ECHR. In turn, the government asserted that the claimant’s detention was not only justified by the need to ensure security in Iraq, but also by the terms of Security Council Resolution 1546 of 2004, which qualified the UK’s ECHR obligations by way of Article 103 of the Charter. Neither the Charter nor the Resolution had been incorporated into English law. The necessary foothold came from the Human Rights Act 1998, which gave effect to the ECHR in UK law. As the Act provided that ECHR rights were only applicable to the extent they were recognized on the international law plane, the court was required to examine the effect of the Resolution to determine the scope of the ECHR in the particular circumstance.191

It is however very doubtful whether there is a broader exception to non-justiciability for unincorporated human rights treaties.195

Thirdly, where the decision-maker explicitly relies on a treaty in making a decision, the courts will apply normal standards of judicial review to the treaty as so relied on.196

(ii)  Judicial restraint and act of state

Policy considerations of a similar kind have led courts to apply a further rule of non-justiciability, holding a claim to be barred if it requires determination of the lawfulness or validity of acts of a foreign state. This is a doctrine of English public law which, long familiar in a general way, still has very uncertain limits.197

Within this principle there are in fact two overlapping doctrines: judicial restraint on the one hand, and act of state on the other. The former is triggered by issues relating to the transactions of states,199 and requires the court to exercise its discretion to determine whether it is sufficiently equipped to handle the dispute. In Buttes Gas, the Court would have been required to address vexed questions of international law arising from the actions of two emirates in the Arabian Gulf with regard to a contested island, Abu Musa, and two competing oil companies claiming concessions within its territorial sea.

Judicial restraint is a discretionary principle,200 but where it applies it is a substantive bar to adjudication, reflecting the incapacity of a national court to deal adequately with certain issues on the international plane. Thus, it cannot be waived, even by the state(s) concerned.201

The concept of act of state forms the hard core of the principle:202 it refers to the non-justiciability in a national court of the acts of a foreign state within its own territory203 or, exceptionally, outside it.204 Thus, in Ex parte Johnson, it was held that once consent to a re-extradition had been obtained by the UK from Austria under the European Convention on Extradition,205 in the form of a diplomatic note, the court could not then proceed to inquire into the quality of the consent so offered.206 As a domestic rule of law, it is distinct from the doctrine of state immunity, a rule of international law.207 Justiciability in this context refers to the act of determining the lawfulness or validityReferences(p. 76) of a foreign act of state performed within its own domain; the court is not prevented from taking note of its existence.208

As with the wider doctrine of non-justiciability, exceptions to the doctrine of act of state nonetheless exist.209The first is that the acts of a foreign state will be justiciable where their recognition would be contrary to English public policy. The exception arose originally with respect to gross human rights violations in Oppenheimer v Cattermole,210 and was expanded in the decision of Kuwait Airways Corporation v Iraqi Airways Company to include acts of state done in clear violation of international law more generally.211 The case concerned the seizure and removal of aircraft owned by Kuwait Airways during the illegal invasion of Kuwait by Iraq in August 1990. But the scope of this exception is uncertain. Lord Steyn stated that not every rule of public international law will create such an exception.212 Lord Nicholls (with whom Lord Hoffmann agreed) stated that the points of law before them were ‘rules of fundamental importance’ and quoted Oppenheim v Cattermole more generally to the effect that ‘[i]nternational law, for its part, recognises that a national court may properly decline to give effect to legislative and other acts of foreign states which are in violation of international law’. Moreover, the exception was applied more broadly to the doctrine of judicial restraint as identified in Buttes Gas, based on the dictum by Lord Wilberforce that abstention was predicated on a lack of ‘manageable standards’. As Lord Nicholls noted, the breach of international law was ‘plain beyond dispute’, and was acknowledged as such by Iraq with its acceptance of the Security Council-mandated ceasefire; accordingly, ‘[t]he standard being applied by the court [was] clear and manageable, and the outcome not in doubt’.213

Thus ‘clearly established’ rules of international law may be considered part of the public policy of the UK,214 as are human rights more generall.215

The second exception arises where Parliament has rendered an issue which is ordinary beyond the competence of the court justiciable. In the first Pinochet case before the House of Lords, Lord Nicholls noted that ‘there can be no doubt that the [act of state] doctrine yields to a contrary intention shown by Parliament’. In that case, the definition of ‘torture’ in section 134(1) of the Criminal Justice Act 1988 and sectionReferences(p. 77) 1(1) of the Taking of Hostages Act 1982 in terms required the investigation of foreign officials in certain cases.

(i)  Treaties

A principal point of difference between the common law tradition as developed in the UK and the tradition that subsequently emerged in the US is the method by which treaties are incorporated into municipal law. In Foster v Neilsen,219 Justice Marshall adopted for the US a modified version of the UK’s dualist model. At its heart was the distinction between self-executing treaties, which by their terms could be incorporated into municipal law without more, and non-self-executing treaties,220 which required enabling legislation to be effective.221

Currently, the central question within US jurisprudence on treaties is the process by which a court determines that a treaty or other international agreement is self-executing. Here, vigorous debate has been prompted by the Supreme Court’s decision in Medellin v Texas,222 which concerned the domestic effect within the US of theReferences(p. 78) decision of the International Court in Avena.223 There the International Court held that the US was in breach of its obligations under Article 36 of the Vienna Convention on Consular Relations (VCCR)224 to provide consular notification to foreign nationals who are detained or arrested. The consequence was an order for the ‘review and reconsideration’ of the cases of 51 individuals so affected. The question for determination by the Supreme Court in Medellin was whether the Charter—which had not been the subject of an enabling statute issued by Congress—was in this respect self-executing.

On this basis, the majority concluded that as the Charter, the Optional Protocol to the VCCR, and the Statute had not been incorporated into US law by way of legislation and the treaties were not themselves self-executing, they could not be given judicial effect.228

As shown by Medellin, the Supreme Court’s current approach utilizes predominantly the text of the treaty.229The ultimate issue is whether the text ‘conveys an intention’References(p. 79) of self-execution.230 In Medellin, the Court appears to have viewed the intention of US treaty-makers as dispositive.231 In addition, although some commentators—and notably the Restatement Third232—had previously taken the position that there was, in cases of ambiguity, a strong presumption in favour of the self-execution of treaties, the Court in Medellin appears to have distanced itself from such a notion, instead requiring that each treaty be considered on its facts, with reference to text, structure, and ratification history.233However, notwithstanding Medellin, important lower courts continue to apply the more nuanced test for self-execution advocated in the Restatement Third.234 In addition, the Supreme Court’s emphasis on text in Medellin is not universally shared. The Senate Foreign Relations Committee, for example, was unhappy with Medellin and modified its procedures in response.235 Moreover, it might be suggested that the Supreme Court’s approach does not accord with the reality of international treaty-making, particularly in a multilateral context: it is not realistic to expect a multilateral treaty involving negotiators from a range of legal cultures to deliberately include in the text of their agreement express language to satisfy the Court’s parochial requirements.236

The final question is the effect—if any—of an unimplemented non-self-execut-ing treaty. As Bradley points out, Medellin is ambiguous on this point.237 The Court rejected the argument that such a treaty merely fails to provide a private right of action within US law, but may still be applied where such a cause of action is not necessary,238 but refused to comment further. As a basic rule, however, a non-self-executing treaty which has not been the subject of implementing legislation has no status in domestic law and is not judicially enforceable.239 In Medellin, the dissent went so far as to imply that the conclusion of such a treaty is to be considered ‘a near useless act’.240

But an analogue of the UK’s presumption of compatibility is present in US law. In Murray v Schooner Charming Betsy, Marshall CJ wrote that ‘an act of CongressReferences(p. 80) ought never be construed to violate the law of nations if any other possible construction remains’.241 In the Restatement Third, this is rendered as ‘[w]here fairly possible, a United States statute is to be construed so as not to conflict with international law or with an international agreement of the United States’.242 The canon was developed to resolve situations in which a treaty or rule of customary international law conflicted with a statute passed later in time by Congress. Ordinarily, this would result in the latter impliedly repealing the former. Charming Betsy by contrast required later statutes to be interpreted, if possible, consistently with the earlier international law obligations of the US. As with the UK presumption of compatibility, the Charming Betsy canon is only applicable where the statute to be interpreted is ambiguous on its face.243

Neither the Charming Betsy nor the Restatement Third makes any distinction between self-executing and non-self-executing treaties. As such, courts have interpreted the canon to breathe life into non-self-executing treaties.244 Such treaties may be held to have codified customary international law;245 more broadly they represent international obligations entered into in good faith from which the US presumably does not wish to depart. Particularly influential is the International Covenant on Civil and Political Rights (ICCPR),246 which was ratified by the US in 1992 with a declaration that Articles 1 to 27 were not self-executing. Despite this, the courts regularly utilize Charming Betsy in order to avoid conflicts with the non-self-executing provisions of the ICCPR.247

The Charming Betsy has been applied to treaties other than the ICCPR,248 may be invoked in a purely domestic context with no international nexus,249 and its relevance does not appear to have been diminished appreciably by the decision in Medellin.250

(ii)  Customary international law

The conventional view of custom252 vis-à-vis the municipal law of the US is therefore that it is a source of law, first in the sense that state and federal courts may apply these rules to determine a dispute, and secondly in the sense that rules of custom, as per the Charming Betsy, are tools of interpretation.253 Thus the Restatement Third:254 ‘[c]ustomary international law is considered to be like common law in the US, but is federal law’. This basic position remains unchallenged: two recent Supreme Court decisions saw no reason to depart from the Paquete Habana.255 But ‘[c]ustomary law does not ordinarily confer legal rights on individuals or companies, even rights that might be enforced by a defensive suit such as one to enjoin or to terminate a violation by the United States (or a State) of customary international law’.256

Customary international law, however, has recently been the cause of considerable scholarly friction,257 with some critics arguing that the monist incorporation of custom into municipal law is inconsistent with principles of democratic governance.258 Dubinsky links these concerns with emerging efforts to diminish the scope of custom in American municipal law, principally through the undermining of the Charming Betsy canon.259 In Serra v Lapin, a case concerning the consistency of prison wages with customary international law, it was said that the Charming Betsy ‘bears on a limited range of cases’260 and could not apply to purely domestic matters that did not inject considerations of international comity.261 In Al-Bihani v Obama,262 the DC Circuit Court of Appeals was called upon to determine whether a foreign national was detained validly pursuant to the 2001 Congressional Authorization for the Use of Military Force (AUMF). Remarkably, Judge Brown, writing for the majority, held that international law could not limit the President’s authority under the AUMF for three reasons. First, the AUMF contained no indication that the customary internationalReferences(p. 82) humanitarian law constituted an extra-textual limiting principle,263 an argument that cuts clear across the line of authorities beginning with the Charming Betsy that such an intention need not be expressed. Second, the laws of war had not been introduced directly into US law via enabling legislation and therefore could not be a source of authority for the court.264 True it is, customary international law could not have provided the detainee in Al-Bihani with rights opposable against the US government,265 but that was not what was sought; rather, Al-Bihani was relying on the AUMF as the source of his rights as interpreted in light of custom. Third, it was said that the laws of war were so vague that they were of limited use in determining the scope of the President’s powers under the AUMF and that moreover, ‘we have no occasion here to quibble over the intricate application of vague treaty provisions and amorphous customary principles’.266 Leaving to one side questions as to the indeterminacy of international humanitarian law, this is—in the words of the separate opinion of Judge Williams—‘hard to square’267 with the decision of the Supreme Court in Hamdin v Rumsfeld which relied explicitly on the laws of war to determine that the AUMF included the authority to detain.268

The DC Circuit, sitting en banc, declined to rehear Al-Bihani v Obama,269 but in refusing the application, the majority took the unusual step of simply issuing a short statement to the effect that the issues of the domestic legal status of the laws of armed conflict addressed in the panel’s decision were not necessary for the disposition of the merits.270

(iii)  The Alien Tort Statute (ATS)271

The ATS gives federal courts jurisdiction272 over cases where the applicable law is customary international law where (a) the plaintiff is an alien, (b) the defendant273 is responsible for a tort, and (c) the tort in question violates international law, includingReferences(p. 83) customary international law. Since the ‘rediscovery’ of the ATS in the 1980s, it has been extensively litigated, breathing life into custom as an element of domestic law in the US. Dozens of actions have been brought, some resulting in sizeable settlements. To date, the claims pursued have related largely to human rights abuses; courts have found that such norms include (but are not limited to) prohibitions on genocide and war crimes,274 torture275 and cruel, inhuman, or degrading treatment,276 summary execution,277disappearances,278 non-consensual medical experimentation on children,279 and forced labour.280 The Supreme Court in Sosa v Alvarez-Machain,281 however, narrowed the scope of those customary international law rules the breach of which could grant a right of action under the ATS to ‘norm[s] of an international character accepted by the civilized world’ that are ‘defined with a specificity comparable to the features of the 18th-century paradigms we have recognized’,282 being those norms with a definite content and similar international acceptance to the rules extant at the time the Act was passed (e.g. offences against ambassadors, violations of safe conduct, and piracy). Thus, in Sosa, the applicant failed in his claim based on ‘the clear and universally recognized norm prohibiting arbitrary arrest and detention’.283 The principles enunciated in Sosa were applied in Sarei v Rio Tinto, with the majority there holding that the plaintiffs’ claims of genocide and war crimes fell within the ATS, whereas claims alleging crimes against humanity arising from a blockade and racial discrimination did not.284

(iv)  Non-justiciability of political questions and acts of state

The doctrines of act of state and the non-justiciability of political questions are analogous to the similar doctrines that exist in the UK. Both are, however, in a state of considerable flux.

Despite the litany of factors given in Baker v Carr, the doctrine has been applied only rarely and idiosyncratically by the Supreme Court and others in a few discrete domestic fields, including political apportionment and gerrymandering,288 impeachment,289 constitutional amendments,290 the political status of foreign countries,291 and most importantly for the purposes of the present discussion, foreign affairs and the deployment of armed forces.292 Thus in Greenham Women against Cruise Missiles v Reagan,293 the decision to deploy American cruise missiles in the UK was held non-justiciable.