This post has been contributed by Professor Paul Arnell, Module Convenor for Public International law.
Public international law may seem remote and apart from domestic law and practice. It might not seem to directly and immediately affect individuals. Both of these perceptions are misplaced. Extradition is one area where the domestic and individual relevance of public international law is clear for all to see. Governing the forcible transfer of accused and convicted persons from one country to another, extradition is a procedure with public international law at its heart. In the UK, courts in England, Northern Ireland and Scotland commonly hear extradition cases, with the vast majority having a basis in a bilateral or multilateral treaty. Extradition in the UK context and more generally provides a useful window through which public international law can be seen and considered.
Public international law generally governs relations between states, although, as we shall see, its rules can directly affect individuals. Amongst its various sources are treaties. They are, of course, one of the sources listed in article 38(1) of the Statute of the International Court of Justice. A recent example of a bilaterial treaty is the Extradition Treaty between the Government of Great Britain and Northern Ireland and the Government of the State of Kuwait 2021 (the 2021 Treaty). This agreement formalised and placed on an international legal basis the process of extradition between the two countries.
The 2021 Treaty entered into force on 10 March 2021. It contains 19 articles which both countries agreed would facilitate extradition between them. As with all treaties, the 2021 Treaty is governed by the Vienna Convention on the Law of Treaties 1969. Perhaps the most important provision of which is article 26, entitled “Pacta sunt servanda”. That article provides that treaties in force between states are binding upon them and must be performed in good faith.
As regards extradition between the UK and Kuwait, article 1 of the 2021 Treaty provides that “The Contracting Parties agree to extradite to each other, pursuant to the provisions of this Treaty, any person who is wanted for trial or punishment in the Requesting State for an extraditable offence”. The Treaty goes on to provide a definition extraditable offences, grounds for refusal of an extradition request, and details of the required procedures and documents. Amongst the grounds for refusal, in article 3, are human rights.
Shedding light on the operation of the 2021 Treaty, from a UK perspective in particular, is a recent English Divisional Court case, Badie v Kuwait [2025] EWHC 2783 (Admin). In this appellate case, objections to the decisions of the district judge and the Secretary of State ordering Badie’s extradition to Kuwait were dismissed. The court held that there were no legal impediments to Badie’s forcible transfer to Kuwait.
Several aspects of the case illustrate the operation and effect of public international law. A first is, simply, that the Kuwaiti request took place under the terms of the 2021 Treaty. The UK was, then, obliged to agree to the request unless one of the stipulated grounds of refusal were met. The request was considered by the UK courts under Part 2 of the Extradition Act 2003. This Part contains the rules that govern extradition requests from countries with which the UK has an extradition agreement (not including the UK’s former EU partners).
A second aspect of the case shedding light on the effect of public international law is that some of the arguments made by Badie against his extradition were based on human rights. These, in the UK domestic context, have their basis in the European Convention on Human Rights and Fundamental Freedoms 1950. This is the leading regional human rights treaty, with 46 state parties. The rights in that treaty became applicable, or justiciable, in UK courts following the enactment of the Human Rights Act 1998. Those rights include the right to be free from torture or inhuman or degrading treatment and punishment under article 3 and the right to respect for private and family life under article 8.
In considering Badie’s arguments against extradition in his appeal the Divisional Court referred to various cases, including some decided by the European Court of Human Rights (ECtHR). Chahal v United Kingdom (1996) 23 EHRR 413 and Othman v United Kingdom (2012) 55 EHRR 1, for example, were cited in the appeal judgment. This reference to ECtHR jurisprudence again highlights the effect of public international law in the UK’s extradition process. In this vein, that particular law was the jurisprudence of an international, though regional, human rights court.
A final example of public international law affecting individuals in the extradition context in this case is found in the issuance and reliance upon diplomatic assurances. These assurances took the form of Kuwaiti promises to the United Kingdom, inter alia, that Badie would be imprisoned in a particular part of the Kuwaiti prison estate if extradited. These assurances, or promises, were made to overcome concerns that were expressed about inhuman punishment in Kuwait. Notably, such assurances are not per se binding in international law. They are also controversial. Diplomatic assurances in this context are perceived by certain commentators and academics and NGOs as inappropriately circumventing legitimate human rights concerns relating to requested persons.
There is no doubt that public international law, in this case in the form of the extradition process, has a real and profound effect in domestic law and practice and on the fate of individuals subjected to it. That is plain to see. There are, of course, many other areas of domestic law and practice affected by public international law. The perception that public international law has little practical relevance on domestic law and practice and the fate of individuals is simply not true.