This article takes a critical look at common law constitutionalism, a theory which has received much support in public law circles of late. The first part of the article elaborates the common law constitutionalist position. The second part of the article assesses the cogency of the theory in terms of its ability to accommodate certain paradigmatic features of judicial review. The article concludes with the suggestion that public lawyers, in their forays into theory, might do better to look to the special role that judicial review plays in assessing the legitimacy of governmental action rather than its supposed connection with ‘fundamental principles of morality’.