The United Kingdom does not have a written constitution, meaning its constitution is “partly written and wholly uncodified.” As a result, the UK’s system of government is one of parliamentary sovereignty. This principle consists of two major components. First, British courts cannot overrule legislation coming from Westminster. This might sound foreign to an American audience, where the U.S. Supreme Court can strike down what laws it deems unconstitutional through judicial review. Second, British law states that no parliament can bind the hands of a future parliament. This means that, in theory, the parliament has final say on legislation governing any British citizen. British parliamentary sovereignty contrasts sharply with the check-and-balance mindset of the American Founding Fathers and with the notion of constitutional supremacy in Germany. Many have argued that domestic as well as international developments in recent decades have both complicated the tenet of parliamentary sovereignty and eroded its principles. On the other hand, political philosophers and legalists challenge the assumption by raising the question of whether parliamentary sovereignty still is, or ever has been, central to the British Constitution.
The proponents of the erosion argument agree that the loss of British parliamentary sovereignty was incremental in nature due to three major domestic developments: devolution, constitutional reforms, and the empowerment of the British central bank and courts. Devolution refers to the process by which the legislative power of Westminster has been increasingly shared by Scottish Parliament, the National Assembly for Wales, and the Northern Ireland Assembly. Parliament’s legislative power has also been devolved to city regions like Greater Manchester, which have gained extra control over local budget and decision making abilities. The Labour government from 1997 to 2007 strengthened the local legislatures and sub-levels of government through other measures. The Local Government Act 2000 allows for referendums on directly elected mayors. In 1997, the Bank of England was granted autonomy over monetary policy, and the Constitutional Reform Act 2005 established the UK Supreme Court, both of which chipped away Westminster’s authority.
Internationally, the UK’s commitment to various multilateral institutions has led to erosion of its national, and thereby parliamentary, sovereignty. The UK enacted The Human Rights Act 1998 at the European Convention on Human Rights (ECHR), which created extra hurdles for Parliament to act autonomously. When the body creates laws deemed incompatible with the ECHR mandate, Parliament is required to revisit its current provisions. The UK also joined the European Union in 1973, binding the UK to European law. The doctrine, known as the “direct effect,” was established in the landmark case of Van Gend en Loos under Article 25 of the EC treaty, the implication being that European law will take precedence upon conflict with UK law.
In the aftermath of several recent high-profile British referenda, including the vote to exit the European Union in 2016, it seems as though public opinion carries more weight in the legislative process than what a state driven by parliamentary, not popular, sovereignty would normally allow. Using referenda to make large legislative decisions (such as the 2011 referendum on Alternative Voting reform), signals the slight but legitimate possibility of a power shift from parliamentary to popular sovereignty. The media and public alike also seem to support the instrument of referendum, as many are calling for a second referendum in the aftermath of Brexit. In any case, these recent developments lead to the conclusion that Westminster’s power is eroding. It also triggers the debate that perhaps Parliament has de jure sovereignty but not de facto autonomy.
Scholars seem split on the question of parliamentary sovereignty, but they mostly agree on the need for certain constitutional reforms. Vernon Bogdanor represents the group that believes parliamentary sovereignty is no longer valid today. Iain McLean, on the other hand, epitomizes the group that challenges the concept of British parliamentary sovereignty as only a recent construct promoted by the conservative establishment. He thinks that the concept was never central to legislative decision-making. In either case, a constitutional reform appears to be the best solution to increase citizen engagement in the government, to reduce the encumbersome House of Lords, and to increase legislative efficiencies. Parliamentary sovereignty, if not relevant to legislative debate, is certainly relevant in terms of revisiting constitutional reform in the post-Brexit United Kingdom.