For a lawyer brought up on the continent of Europe, an examination of the United Kingdom’s legal system, particularly its highest court, the House of Lords, produces something of a shock. There is the initial shock that derives from seeing how two great legal cultures, embodying two distinct modes of thinking about the law, confront each other as they try to embed and extend their influence throughout the world. The sacrosanct dividing line between common law and Romano-Germanic law is a plain fact that cannot be denied and it strikes any casual observer forcibly. But a further shock flows from this first one. It relates to the place of the House of Lords at the heart of European constitutionalism. We all know that the highest British court is not itself a ‘Constitutional Court’, given that there is no written British constitution. But, notwithstanding the special nature of British constitutional law, the judicial arm of the House of Lords and the Judicial Committee of the Privy Council constitute two bodies, comprising mostly the same judges, which retain the power to interpret laws in the light of constitutional principles, in particular principles of common law, and also the power to control the division of competences between the constituent parts of the United Kingdom. The House of Lords is therefore a kind of constitutional court, but its powers and ways of operating are clearly not within the mainstream which one French constitutional expert describes as ‘the European constitutional justice model'. The essential feature of this ‘model’ is judicial oversight of what is constitutional. But we should be careful not to delude ourselves. Continental constitutional justice is heterogeneous in nature: its uniformity is deceptive. The European constitutional justice model presents, on the surface, a certain uniformity, but when one looks more closely at European constitutional courts, the key characteristic which comes to the fore is diversity.