ENGLISH public law has gained in coherence with the gradual disappearance of rigid doctrinal barriers to judicial review. The repudiation of earlier restrictions on review of ministers’ exercise of the royal prerogative marked a particularly significant step towards a more rational system of legal control. It is true that acknowledgement of the susceptibility of prerogative decisions to judicial review, in principle, was accompanied by warnings about the constraints of justiciability in practice; but the various supposed categories of non-justiciable decision-making have been gradually breached and eroded in the course of common law development. When individual rights have required protection, neither the formal source of the power in question nor its intrinsically discretionary character have proved impenetrable barriers to judicial scrutiny.