In this paper, I use Dworkin's distinction between rules and principles to analyse the doctrine of parliamentary sovereignty. I argue that, inherent in many conceptions of the doctrine, is an assumption that it operates in the conclusive manner of a Dworkinian rule. I then submit that the doctrine actually functions in the flexible way characteristic of a Dworkinian principle. In support of this contention, I argue that Acts of Parliament may be balanced against competing principles or statutes; that they possess the dimension of weight or importance; and that the degree to which they will be adhered in any particular case will be contingent upon the importance attributed to any competing principle or statute. I finish the paper with an evaluation of my arguments and an attempt to anticipate potential counter-arguments.