Introduction

As has already been noted, much of the uncertainty surrounding separation of powers in the UK constitution can be traced back to the myriad interpretations of the doctrine that have, over time, been proposed. Yet the idea that judges should not be seen to legislate – to create law rather than to interpret it – has historically provided one of the more certain dividing lines between the respective functions of the three branches of government in the constitution of the UK. The tradition of what Stevens has termed ‘substantive formalism’, which dominated judicial attitudes and method for much of the twentieth century, ironically gave rise to a relatively rigid conception of separated governmental functions under which ‘the function of the legislature is to make the law, the function of the administration is to administer the law and the function of the judiciary is to interpret and enforce the law’.

It is, of course, central to the Diceyan understanding of parliamentary supremacy that no other constitutional body possesses legal power which can challenge that of Parliament; as such, the judiciary have no generally applicable competence to strike down or question the authority of primary legislation, nor do the judges have power to act in a way which would otherwise usurp the legislative function. As we have seen, the HRA attempts, in theory, to preserve Parliament's role as sovereign legislature and therefore preserve the constitutional equilibrium.