The concept of parliamentary sovereignty is widely considered to be the central concept for the British constitution. Essentially, parliamentary sovereignty recognises the idea that parliament is the supreme law making body within the UK. Unlike other countries such as the USA or Germany, the UK does not have one single text for its constitution and is un-codified. This does not, however, reduce its central importance to the UK constitutional processes.
Parliamentary sovereignty is quite simply the priority that parliament has over other law making bodies. Critically, parliament cannot make any decisions that would bind future parliaments. This essentially removes the chance of having a codified constitution as this would require the removal of parliamentary sovereignty, before a written constitution could become enshrined into British law. The concept of sovereignty goes back several centuries; until 1689, it was the monarch who held the ultimate power. This was changed to give parliament the top political and law making role, although the monarch is still heavily involved (albeit largely nominally).
This situation of parliamentary sovereignty means that the judiciary cannot block a law from being passed. Contrast this with the USA where the Supreme Court has the power to strike down an act with which it does not agree. The idea of parliamentary sovereignty was laid out by AV Dicey in Law of the Constitution, back in 1885, where he stated: "In theory Parliament has total power. It is sovereign". This he felt was based on four factors: first, that parliament has the competence to pass any law on any subject; second, that the laws established by parliament can control any person in any location; third; that no laws can bind successive parliaments; and fourth, that the courts do not have the jurisdiction to challenge the decisions of parliament.
Despite the importance of the doctrine of parliamentary sovereignty, there have been some important recent limitations on this concept. In 1972, the UK entered the European Union which many have said substantially limits the current doctrine of sovereignty. Under the EU constitution, it is now recognised that European law can have direct effect on the subjects of member states. This was established in the leading case of Van Gend en Loos, where the direct effect of Article 25 of the EC treaty (as it is now) relating to the free movement of goods could be directly relied upon by individuals within the member states. In the court's judgement, the existence of this new legal order was recognised, stating categorically that the European law could be seen as supreme to national parliament. It was stated that the EC treaty "…constitutes a new legal order of international law for the benefit of which the states have limited their sovereign rights, albeit within limited fields and the subjects of which comprise not only member states but also their nationals. Independently of the legislation of member states, community law therefore not only imposes obligations on individuals but is also intended to confer upon them rights which become part of their legal heritage".
This jurisprudence has shown the clear intention of the EU to be seen as the supreme law making body and that, where there is conflict, European law will take precedence, which is a substantial limitation on the ultimate authority of parliament. This was also expressed in Thoburn v Sunderland City Council. In this case, it was held that the concept of implied repeal could not be considered to be effective when it came to certain constitutionally important acts such as the European Communities Act 1972. One of the primary factors of parliamentary sovereignty is the concept that one parliament cannot be bound by the previous parliament. Therefore, where there are two acts in conflict, the latter takes precedence. However, in this case, it was held that the earlier European Act took precedence, suggesting a further erosion of the principle of parliamentary sovereignty.
A further seeming limitation of parliamentary supremacy has been established in the form of the Human Rights Act 1998. One of the key factors of parliamentary sovereignty has been the division of power between the judiciary and parliament. The judiciary does not, under the rules of parliamentary sovereignty, have the power to challenge the decisions of parliament.
The Human Rights Act 1998 was enacted into British law as a result of the European Convention on Human Rights. Critically, section 3 of the 1998 act states: "So far as it is possible to do so, primary legislation and subordinate legislation must be read and given effect in a way which is compatible with the Convention rights". Furthermore, section 4 allows the courts to make declarations of incompatibility where domestic legislation is in conflict with the rights under the ECHR. Although this process is seen as a last resort and the judiciary has been required, where possible, to read primary legislation in a way that is compatible with the ECHR, there is still the ultimate power to state that the primary legislation is incompatible. It should be noted, however, that the incompatible legislation will remain in force until parliament changes the legislation.
Although this has not fully eroded the principle of parliamentary sovereignty, the true effect can be seen in the case of A and Others v. Secretary of State for the Home Department, where the judiciary made a declaration of incompatibility in relation to Part 4 of the Anti-terrorism, Crime and Security Act 2001. Based on this, parliament changed the legislation in the Prevention of Terrorism Act 2005. Therefore, although the judiciary does not have the power to change the legislation laid down by parliament, it can challenge parliament and require it to re-visit its current provisions.
Parliamentary sovereignty has been the vital cornerstone of constitutional law in the UK for several centuries. Despite this, recent events relating to joining the European Union have limited the supreme power that parliament had by eroding two of the main factors referred to by Dicey. Firstly, the judiciary has a much more political role by virtue of the Human Rights Act 1998, thus allowing it to challenge the decisions of parliament; and secondly, there is now a higher body of law that has direct effect on the UK. Both of these factors have acted to limit, but not remove, the traditional concept of parliamentary sovereignty.
Dakolias, Maria, Are We There Yet? Measuring Success of Constitutional Reform, Vanderbilt Journal of Transnational Law, 39, 2006
Dicey, Albert Venn, Lectures Introductory to the Study of the Law of the Constitution, Macmillan, 1886
Fenwick, Helen, Phillipson, Gavin, Constitutional and Administrative Law, Routledge, 2003
Goldsworthy, Jeffrey Denys, The Sovereignty of Parliament: History and Philosophy,
Oxford University Press, 1999
Jones, Alistair, Britain and the European Union, Edinburgh University Press, 2007
MacCormick, Neil, Questioning Sovereignty: Law, State, and Nation in the European Commonwealth, Oxford University Press, 1999
Mackay Irvine of Lairg, Alexander Andrew, Human Rights, Constitutional Law and the Development of the English Legal System: Selected Essays, Hart Publishing, 2003
Turpin, Colin, Tomkins, Adam, British Government and the Constitution: Text and Materials, Cambridge University Press, 2007
Young, Ernest A., Public Law, Constitutional Commentary, 21, 2004
 Goldsworthy, Jeffrey Denys, The Sovereignty of Parliament: History and Philosophy,
Oxford University Press, 1999
 Dicey, Albert Venn, Lectures Introductory to the Study of the Law of the Constitution, Macmillan, 1886
 Young, Ernest A., Public Law, Constitutional Commentary, 21, 2004
 NV Algemene Transport- en Expeditie Onderneming van Gend & Loos v. Netherlands Inland Revenue Administration  ECR 1
 Jones, Alistair, Britain and the European Union, Edinburgh University Press, 2007
  Eu. L.R. 587
 Turpin, Colin, Tomkins, Adam, British Government and the Constitution: Text and Materials, Cambridge University Press, 2007
 MacCormick, Neil, Questioning Sovereignty: Law, State, and Nation in the European Commonwealth, Oxford University Press, 1999
 Fenwick, Helen, Phillipson, Gavin, Constitutional and Administrative Law, Routledge, 2003
  UKHL 56
 Dakolias, Maria, Are We There Yet? Measuring Success of Constitutional Reform, Vanderbilt Journal of Transnational Law, 39, 2006
 Mackay Irvine of Lairg, Alexander Andrew, Human Rights, Constitutional Law and the Development of the English Legal System: Selected Essays, Hart Publishing, 2003