The two European referendums of 1975 and 2016 are examined in their historical, political and constitutional context. The paper provides a short account of United Kingdom’s accession and participation in the European Union. The uneasy relationship with the EU is shown, with reference to political process of negotiating Britain’s position in the Union. Some political, economic and cultural factors that have shaped British attitudes towards European integration are analysed. A legislative framework for both referendums is described and the dynamics of pre-referendum debates and campaigns are discussed. The political implications of ‘Leave’ vote (in favour of Brexit) are indicated. Finally, certain constitutional and legal issues surrounding UK withdrawal from the EU are considered, also in the context of the doctrine of parliamentary sovereignty.

In recent years, the United Kingdom has seen a growing doctrinal discourse around competing models of legal and political constitutionalism. The situation has been exacerbated by ongoing changes in both theory and practice, which have engendered a strong conviction that the UK is now departing from the political constitutionalism associated with the traditional model of parliamentary sovereignty, in which Parliament’s legislative power is unlimited by law and the courts have no right to question the validity of laws on substantive grounds. From a theoretical point of view, legal constitutionalists contributed to provoking this change while desiring to continue to promote it by moving almost completely and exclusively towards legal constitutionalism, thus supplanting its political formula. From a practical point of view, however, one should bear in mind that the events that led to a specific change in thinking about British constitutionalism encompass, in particular, the legal consequences resulting from the UK’s membership in the European Union, including the phenomenon of the so-called judicial activism. Nevertheless, these events were also induced by the expansion and strengthening of judicial review of administrative actions, judicial shaping of the principle of legality, as well as by the enactment and application of the Human Rights Act 1998.