This talk will consider legal control of the exercise of the prerogative and common law powers of the Crown through judicial review.  In particular, I will ask how legal analysis based on what are sometimes called “fundamental rights”, or common law constitutionalism, has a bearing on the exercise of the Crown’s powers. It is argued that this is through their impact on application of the rationality standard of review, rather than by being treated as free-standing positive rights recognised in private law.