British judges who were interviewed considered that citations of foreign law, including general principles of law, mostly occur in human rights cases and in private law cases. The use of foreign law is less frequent in criminal cases. In human rights cases, the British judges hope to find guidance in case law concerning the interpretation of the Convention for the Protection of Human Rights and Fundamental Freedoms (ECHR) or concerning comparable instruments for human rights protection. In contract and tort cases, the judges consider that the shared background with other common law legal systems makes legal comparison often useful.

Concerning principles related to the protection of human rights, a British judge remembered having looked at French case law in a case which concerned the balancing of the anonymity of parties and the interest of media coverage in the light of the right to a fair trial and the principle of open justice. Another judge, speaking about the same legal question, mentioned having searched German law and having made inquiries with personal contacts in Germany in order to find useful information, which then might give rise to a question to counsel to base arguments on this information. In the decision given on 27 January 2010, Lord Rodger, who delivered the unanimous judgment, remarked that:

Unfortunately, no real additional help with the question of anonymity orders can be obtained from examining the practices of courts in Europe when issuing judgments. In all the principal systems, at least, steps can apparently now be taken, where appropriate, to anonymise reports of matrimonial disputes and disputes relating to children. Apart from that, however, what is striking is the variety of approaches.⁹

This observation was followed by an overview of French, Italian and German case law.¹⁰ The responses of the interviewed judges and the reasoning in the judgment suggest that the comparative analysis in this case was carried out with the aim to get a clearer insight into the state of the domestic law. The observed variety of approaches can be considered a justifying argument for the decision taken, which stays very close to the facts of this specific case. Furthermore, the foreign case law gives an indication of factors to be taken into account when balancing the right of privacy against the rights of the press. In this way, the knowledge of the practices in other legal systems seems to have helped the judges to mark out the relevant questions during the process of discovery.

Concerning the reference to foreign principles in private law cases, judges sometimes take account of “soft law” instruments which are considered to have a certain prestige. References to the Principles of European Contract Law (PECL), developed by the Lando Commission,¹¹ can be found in a small number of judgments of the Law Lords and the UK Supreme Court. A search of BAILII yielded five judgments given between 2001 and 2009.¹² However, these references appear to have no impact on the interpretation of domestic law. They are used as guidance for the interpretation of European law, such as the directive on unfair terms in consumer contracts,¹³ or to highlight the differences between the UK and the continental legal traditions. This latter argument transpires, for example, from the opinion of Lord Hoffmann in Chartbrook Ltd v. Persimmon Homes Ltd, in which the judge observed that the PECL and related instruments “reflect the French philosophy of contractual interpretation, which is altogether different from that of English law”.¹⁴ An interviewed judge further considered that taking into account the PECL or the Draft Common Frame of Reference (DCFR) developed at the initiative of the European Commission would not make sense, because this source is too vague and academic in comparison with the domestic law. This judge considered that the DCFR might develop into an optional system in Europe “as an ever closer union”.¹⁵ However, it is this judge’s belief that practical hindrances to commerce will remain as a result of efficiency considerations and costliness. The judge therefore considered that the DCFR can be no more than an inspiration for the UK Supreme Court.

An example from the Supreme Court of Canada’s case law concerns the interpretation of domestic legal norms in light of international law, in this case customary international law. In Suresh v. Canada (Minister of Citizenship and Immigration),¹⁶ the Canadian authorities wanted to extradite a Sri Lankan immigrant who allegedly posed a security risk. However, when sent back to Sri Lanka, this person would run the risk of being tortured. The Supreme Court considered the following with regard to the role of the international perspective:

We have examined the argument that from the perspective of Canadian law to deport a Convention refugee to torture violates the principles of fundamental justice. However, that does not end the inquiry. The provisions of the Immigration Act dealing with deportation must be considered in their international context: Pushpanathan, cit. Similarly, the principles of fundamental justice expressed in s 7 of the Charter and the limits on rights that may be justified under s 1 of the Charter cannot be considered in isolation from the international norms which they reflect. A complete understanding of the Act and the Charter requires consideration of the international perspective. International treaty norms are not, strictly speaking, binding in Canada unless they have been incorporated into Canadian law by enactment. However, in seeking the meaning of the Canadian Constitution, the courts may be informed by international law. Our concern is not with Canada’s international obligations qua obligations; rather, our concern is with the principles of fundamental justice. We look to international law as evidence of these principles and not as controlling in itself.¹⁷

The Supreme Court of Canada then investigated whether the prohibition of torture is a peremptory norm or ius cogens, an argument which was advanced by the intervener, Amnesty International. On this point, the Court made the following observation:

Although this Court is not being asked to pronounce on the status of the prohibition on torture in international law, the fact that such a principle is included in numerous multilateral instruments, that it does not form part of any known domestic administrative practice, and that it is considered by many academics to be an emerging, if not established peremptory norm, suggests that it cannot be easily derogated from.¹⁸

The Court continued with the interpretation of the conflicting international legal instruments which were at issue in this case, namely, the International Covenant on Civil and Political Rights (ICCPR), the United Nations Convention Against Torture (CAT) and the Refugee Convention. Furthermore, the Court took into account the position taken by the United Nations Committee Against Torture, and relevant judgments of the Supreme Court of Israel (sitting as the High Court of Justice) and the House of Lords rejecting the use of torture as a legitimate tool in the fight against terrorism. The Supreme Court concluded:

That the better view is that international law rejects deportation to torture, even where national security interests are at stake. This is the norm which best informs the content of the principles of fundamental justice under s 7 of the Charter.¹⁹

In applying this view to the Immigration Act, the Supreme Court cited the opinions of Lord Hoffmann and Lord Slynn in the British Rehman case, which concerned a similar legal question.²⁰ Balancing all arguments thus collected, the Supreme Court of Canada pronounced as its judgment that torture constitutes a violation of the Charter, but that an exceptional case might occur in which extradition of an individual to a Country where this person faces the risk of torture could be allowed under section 53(1)(b) of the Immigration Act.²¹

It seems that international and comparative law were used in this case in order to clarify the possible meanings of the domestic law. The study of the relevant international legal norms also enabled the Court to ensure the consistency of Canadian practice with international law, and in this way to confirm the respect of the Canadian authorities for international law.²² The acknowledgment of the possible occurrence of exceptional cases in the future fits the common law tradition of leaving space for the further development of the law.

The motives of the highest courts when selecting specific foreign legal sources often seem to come down to the emphasising of unity of values with other liberal-democratic regimes, such as the ECHR. However, comparative law is sometimes used in another way as well. An example is the Supreme Court of Canada’s judgment in the case of United States v. Burns. In this case, the Supreme Court decided that it was unconstitutional under the Charter to extradite two Canadian citizens, suspected of criminal acts, to the United States if no assurances were given that the death sentence would not be imposed or carried out.²³ This decision overturned earlier judgments of the Court, in which the extradition of US residents was not prevented.²⁴ The Court’s reasoning contained a reference to international experience and a comparison with other Countries and with the US legal system:

International experience … confirms the validity of concerns expressed in the Canadian Parliament about capital punishment. It also shows that a rule requiring that assurances be obtained prior to extradition in death penalty cases not only accords with Canada’s principled advocacy on the international level, but is also consistent with the practice of other Countries with whom Canada generally invites comparison, apart from the retentionist jurisdictions in the United States.²⁵

By emphasising the exceptional position of the US with regard to the death penalty, the Supreme Court of Canada justified its refusal to allow the extradition to the United States. The Court backed up its judgment further by citing supporting case law of the European Court of Human Rights (ECtHR; Soering v. United Kingdom), the South African Constitutional Court (S. v. Makwanyane), and the English Court of Appeal.²⁶ In this way, the Supreme Court of Canada used the argument of almost universal consensus to enhance the legitimacy of a judgment which departed from the Court’s previous case law and to set itself apart from the other legal system (that of the United States) involved in this case.

Interestingly, foreign factual experience concerning potential wrongful convictions was invoked in the Burns judgment as one of the arguments justifying the Court’s reversal of its Kindler and Ng jurisprudence. The assessment of facts in light of the principles of fundamental justice, underlying the Canadian legal system, led to a different balancing of outcomes:

The outcome of this appeal turns on an appreciation of the principles of fundamental justice, which in turn are derived from the basic tenets of our legal system. These basic tenets have not changed since 1991 when Kindler and Ng were decided, but their application in particular cases (the “balancing process”) must take note of factual developments in Canada and in relevant foreign jurisdictions. When principles of fundamental justice as established and understood in Canada are applied to these factual developments, many of which are of far-reaching importance in death penalty cases, a balance which tilted in favour of extradition without assurances in Kindler and Ng now tilts against the constitutionality of such an outcome. For these reasons, the appeal is dismissed.²⁷

An example from the United States concerned the interpretation of domestic law implementing international treaty norms. This topic was addressed by the Supreme Court in a case concerning the envisaged extradition of a person to Ethiopia. It had to be decided whether this alien, who had assisted or participated in persecution under duress, could be eligible for asylum in the United States.²⁸ The petitioner referred among other things to “concepts of international law” to argue that the notion of “persecution” used in the Immigration and Nationality Act included the requirement of “moral blameworthiness”.²⁹ In the discussion of the arguments put forward by both sides, Justice Kennedy, writing for the majority in the US Supreme Court, considered:

The persecutor bar in this case… was enacted as part of the Refugee Act of 1980. Unlike the [Displaced Persons Act of 1948], which was enacted to address not just the post war refugee problem but also the Holocaust and its horror, the Refugee Act was designed to provide a general rule for the ongoing treatment of all refugees and displaced persons. As this Court has twice recognized, “‘one of Congress’ primary purposes’ in passing the Refugee Act was to implement the principles agreed to in the 1967 United Nations Protocol Relating to the Status of Refugees, Jan 31, 1967, 19 UST 6224, TIA S 6577 (1968)”, as well as the “United Nations Convention Relating to the Status of Refugees, 189 UNTS 150 (July 28, 1951), reprinted in 19 UST 6259” (Aguirre-Aguirre, 526 US, at 427, quoting Cardoza-Fonseca, 480 US, at 436–437).³⁰

This consideration reflects an effort to interpret the domestic law in conformity with international legal norms. The Supreme Court considered that the Board of Immigration Appeals had misapplied an earlier precedent of the Court and because of this mistaken application had not taken into account the alien’s motivation and intent when determining whether the alien had assisted in persecution.³¹ The case was remanded for further proceedings.

As another example, an interviewed judge mentioned that foreign references played a role in cases judged by the Supreme Court in the 1970s concerning women’s rights. This judge mentioned the case of Reed v. Reed, which concerned the contestation by the mother of a deceased child of a statute preferring males over females in the administration of an estate.³² Counsel in this case cited case law of the German Bundesverfassungsgericht to support its argument that the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution had been violated. The Supreme Court ruled in favour of the petitioner, in this way acknowledging the constitutional basis for the protection of individuals against discrimination based on gender.

International opinion and the practices of other States, in particular the United Kingdom, were also taken into account by the US Supreme Court in the case of Roper v. Simmons to support the judgment of unconstitutionality of the juvenile death penalty.³³ In the majority judgment delivered by Justice Kennedy, the Supreme Court found support for its judgment in “the overwhelming weight of international opinion against the juvenile death penalty”, which “while not controlling [the Court’s] outcome, does provide respected and significant confirmation for [the Court’s] conclusions”.³⁴ In a dissenting opinion, Justice Scalia criticised the majority’s argument, stating that:

The Court thus proclaims itself sole arbiter of our Nation’s moral standards–and in the course of discharging that awesome responsibility purports to take guidance from the views of foreign courts and legislatures.³⁵

The disagreement in the Roper case is illustrative of the controversy which has developed in legal and academic debate in the United States in the last decades regarding the reference to non-binding foreign law. Justice Scalia is an important contributor to this debate. He has argued that international law which has not been integrated into the national legal system should not be used as an interpretive tool, since this practice would mean bypassing the normal process of integration of international law in the domestic legal system. Justice Scalia has further argued that there is no useful purpose to the use of comparative law or international opinion in the process of interpreting one’s national law.³⁶

In France, the Cour de cassation is the supreme judge in civil and criminal cases and the Conseil d’État is the supreme administrative judge. The Conseil constitutionnel, since the introduction of a posteriori review of legislation in 2009, has acquired the status of a true constitutional judge, able to protect the rights of citizens in concrete cases.

Concerning the reference to general principles of law, in particular in human rights cases, an analysis of the practice of the Conseil constitutionnel reveals an interesting development. In its case law, the Conseil constitutionnel has established that its competence is limited to the review of parliamentary acts in the light of the Constitution. The conformity of these acts to international treaty law formally is not tested.³⁷ However, an interviewed judge indicated that, notwithstanding this case law, the members of the Council have developed the practice to check their interpretation of fundamental constitutional rights in light of the interpretation given by the ECtHR to human rights protected by the ECHR. The reasons for the change of practice of the Conseil constitutionnel are of a mixed legal and political nature. In order to prevent cases from going up to Strasbourg, the members of the Conseil constitutionnel consider it desirable that legislation is checked for its conformity to the European Convention. Moreover, this review benefits the guarantee of the unity of the law and legal certainty in the French legal system, in which the other highest courts and the trial courts, in relevant cases, consider the conformity of legal provisions to the ECHR.³⁸

According to the interviewed French judge, in principle there is no reason to give a different interpretation from the ECtHR as concerns the meaning of fundamental rights. Therefore, if the national judge wants to adopt a different solution, he should justify this. Such a justification might be found in the specificity of the national legal system, for example, as concerns the right to religious freedom and the French principle of “laïcité” (secularism). In this light, mention can be made of the high-profile case concerning the constitutionality of a legislative act prohibiting the concealment of one’s face in public. This law was aimed in particular at the prohibition of the burqa, a garment worn by certain Muslim women. The awareness of the members of the Conseil constitutionnel of the ECtHR’s case law can be deduced from the presentation of relevant materials in the “dossier documentaire” which is prepared by the Council’s documentation service. In the aforementioned case, this file contained extracts from four judgments of the European Court.³⁹ The idea of coherence of transnational judicial interpretations thus has induced an “enrichment” of the deliberations of the constitutional judge. However, this awareness is not shown in the reasoning of the Council’s decisions, which will only contain the result of the conformed interpretation. In case of the predominance of a specific French constitutional principle, such as the principle of “laïcité”, the Council only presents an argument based on this principle. Indeed, the aforementioned decision did not explicitly address the interpretation given by the ECtHR regarding the right of religious freedom.