This paper, which is based on a paper given at a seminar held at the University of Glasgow in November 2005, discusses the sovereignty of Parliament in the light of the decision of the House of Lords in Attorney General v Jackson, which considered the question of whether the Parliament Act 1949 and the Hunting Act 2004 were valid Acts of Parliament. The paper begins by explaining the background to the litigation, before going on to summarise the decision. Next, it briefly analyses the preliminary issues of standing and jurisdiction involved in the case, before going on to consider how the political background and political practice affected the decision of the House of Lords on the key questions in the case. The major part of the paper is devoted to a discussion and analysis in the light of constitutional theory of the extensive dicta in the case on the principle of the sovereignty of Parliament, which contrasts positivist and Dworkinian perspectives, and considers the question of whether the orthodox view of sovereignty is likely to be displaced in the foreseeable future by the view that Parliament’s legislative power is subject to legal constraints. The paper concludes that such a change in the rule of recognition is unlikely to come about merely because the judges change their view of the content of fundamental doctrines; changes of this nature require the assent of the other institutions of government.