This review article discusses the relationship between deference and the presumption of constitutionality, as discussed in Brian Foley’s book, Deference and the Presumption of Constitutionality. Foley argues for the rejection of the presumption of constitutionality as it operates in the Irish Constitution, proposing instead a ‘due deference’ approach. This approach would require courts to give varying degrees of weight to the legislature’s conclusions that particular legislative provisions are constitutional. The article praises Foley’s book, particularly its stronger justification of due deference (...) which focuses on its ability to foster a culture of justification which, in turn, facilitates popular sovereignty. The review also provides a criticism of the argument made in the book and discusses its application to the UK constitution. First, the review argues that the focus on constitutional as opposed to institutional factors to determine deference may, in practice, undermine Foley’s justification of due deference. Second it argues that Foley’s justification of deference may be best served in the UK constitution by a theory of democratic dialogue as opposed to the application of due deference. (shrink)