Engagement and Disengagement with International Institutions: The UK Perspective

Abstract

This chapter considers the UK legal rules that govern engagement and disengagement with international institutions. The discussion begins with consideration of the rules that shape initial treaty engagement with such institutions. The UK is fundamentally a dualist system, such that the basic starting point is that statutory incorporation of treaties is a condition precedent to their application in UK law, although the breadth of this rule has been questioned, as will be seen from the analysis. UK law also contains statutory provisions that, subject to certain conditions, accord a veto power to the House of Commons to prevent the executive ratifying a treaty, thereby preventing the UK from being bound by international law obligations. This analysis concludes with discussion of the limits of dualism, as manifest in the making and application of rules at the global level that can have an impact, de jure or de facto, on the nation state. The focus in the second part shifts to what is termed continuing engagement. This concerns constraints flowing from national law while the UK is a member of an international organization. The nature and content of such constraints can vary, as can their conceptual foundation. The discussion considers three types of constraint: statutory, common law, and those grounded in the desire for autochthony.

The final part of the chapter addresses the UK rules concerning disengagement from an international organization. The starting point is that the executive, acting pursuant to prerogative power, negotiates disengagement from an international organization, and Parliament then enacts or repeals the legislation to make this a legal reality in national law. There are, however, limits to the prerogative: it cannot be used to alter the law of land or affect rights, and it cannot be deployed to circumvent a statute that covers the same ground. There was contestation as to the meaning of these precepts in litigation concerning the UK’s exit from the EU.

Keywords: dualist, treaties, parliamentary sovereignty, constitutional constraints