Introduction

All law is shaped by its historical development. If anything, this is particularly true of foundational principles. These have a greater tendency to endure hard-wired in inter-generational thinking than detailed rules, which may more readily be re-evaluated and recast. The legal principles on which foreign relations are conducted have become one of the pressing issues of contemporary public law. But the widespread changes in this field, examined in this work, have taken place against a continuing debate about the extent to which an exclusionary approach is supported in a deep way by common law constitutional thought. So, in 2010 the Supreme Court of Canada cited Dicey as authority for the proposition that the foreign affairs power is a matter for the prerogative. In 2000 Lord Hoffmann, writing for the majority in a deeply divided Privy Council, said: ‘The rule that treaties cannot alter the law of the land is but one facet of the more general principle that the Crown cannot change the law by the exercise of its powers under the prerogative. This was the great principle which was settled by the Civil War and the Glorious Revolution in the 17th century.’ How may these exclusionary rules be reconciled with the principle, supported, as Lord Bingham said in 2006, by the ‘old and high authority’ of Lord Mansfield and Blackstone, that ‘the law of nations in its full extent is part of the law of England and Wales’?

It is therefore of considerable importance to understand the origin of the ideas underlying foreign relations law. In that way, it will be possible to assess their continuing relevance and application in the modern legal system. The argument that will be presented in part B of this chapter is that the outlines of the traditional position do bear the indelible imprint of twin seventeenth-century forces, specifically (a) the reservation to the executive of what John Locke called the ‘federative power’ to conduct foreign relations following the Glorious Revolution of 1688; and (b) the interposition of parliamentary sovereignty which confirmed the strict division between the international and national planes of law-making.