The Domestic Application of International Law in British Courts

Abstract

Abstract This chapter considers the use and application of international law in British courts. Consideration is given to developments that have led to the increasing use of such law and to the fact that compliance with international law is now a central part of evaluating the lawfulness of executive actions. The chapter explains that the primary underpinning of the dualist British system is the constitutional principle of Parliamentary sovereignty and the corollary that an exercise of the royal, executive, prerogative does not enable ministers to change the law, unless such a power is expressly conferred by statute. It explains that although this constitutional framework is clear as a matter of principle, the application of it, in discrete cases, gives rise to continuing debate. The chapter describes the use of treaties that are formally incorporated into domestic law (incorporated treaties), those that are not so incorporated (unincorporated treaties), and customary international law. Consideration is given to the way in which British courts approach treaty interpretation and the canons of interpretation that are deployed in relation to unincorporated treated (the presumption of compatibility and the principle of legality). The chapter notes that there are other cases that may raise issues of international law, such as where a British court is invited to adjudicate on the lawfulness of a foreign state’s conduct. It concludes that British courts have a flexible and open approach to the possibility of using and applying international law obligations and standards, especially in the context of assessing the lawfulness of executive action, subject to the important caveat that it must be constitutionally permissible and institutionally appropriate.