Our constitution is dominated by the sovereignty of Parliament
Sovereignty is defined as the supreme authority in a state, to impose law on everyone else and alter any pre-existing law. Therefore the “parliamentary sovereignty" in its simplest terms, means it is the Parliament who has the authority to enact, amend and repeal the laws in the state.
There are differing approaches among past and present scholars as to how this Parliamentary authority emerged and took shape. The orthodox views of Dicey and Wade, as summarised by P. Craig  , stipulate that Parliament’s authority is absolute: the legislation enacted cannot be invalidated by courts, latest will of the Parliament will dominate an earlier Act, repealing past legislation, therefore theoretically it seems impossible to entrench certain pieces of legislation and bind future Parliaments. The common law view (New View) on the other hand says Craig, held by Lord Jennings, Heuston and Marshall, maintains that it is the courts who apply the Acts of the Parliament give legitimacy to parliamentary sovereignty.
K. Armstrong,  also adds two more approaches from different scholars: the “Pluralist" approach, which considers the EU to be a superior legal authority that created a new constitutional hierarchy (Mitchell); or that different legal orders were (trying to) coexist in harmony, without hierarchical separation (MacCormick). The fourth approach would be the “Sceptical" approach, which claimed that the actual controlling authority was the Executive, therefore Parliament could not be said to have absolute sovereignty (Griffith).
The approaches, while diverging on the source and extent of sovereignty, are mostly concurring on the fact that some measure of parliamentary sovereignty exists. The question is whether this sovereignty was ever absolute. This essay will argue that while the initial aim was an absolute parliamentary sovereignty, the internal and global developments have had material effect on creating certain limitations.
Inception of parliamentary sovereignty
P. Leyland explains that, “since the Bill of Rights of 1689, the courts have recognised Acts of Parliament as the highest source of law… it was noted in the opening chapter that the Bill of Rights of 1689 makes the Crown subject to the will of the Parliament and that it also recognizes that the Parliament (Crown, Lords and Commons) has unlimited legislative authority"  . We see that, at least at the time of its inception, the Parliament had absolute power in enacting laws and thus governing the country. Such power, prima facie, did not seem to have any limits but qualifications emerged through time.
The courts, have shaped this power to have certain boundaries such as protecting private persons’ rights, through their decisions of limiting the powers of the Crown and the Secretary of State to interfere with the person or the property of citizens without lawful authority (Entick v Carrington  ). This aim was cemented with the Human Rights Act (HRA) 1998 s.4 which gives the courts the right to issue a declaration of incompatibility if an Act of Parliament was found to be in breach of a Convention right.
The most recent authority on whether the validity of the Acts of Parliament could be questioned came about in the case of Jackson v Attorney General  . The validity of Hunting Act 2004 had been put as a question to the House of Lords (due to the fact that it had been passed under the powers of Parliament Acts 1911 and 1949 which greatly reduced the powers of the House of Lords) who did, in fact find the Act valid. However the important point of that case was that the courts were considered to be entitled to decide on the validity of an Act of Parliament. P. Leyland asserts that “..an emerging judicial view … questions the unqualified supremacy of the Parliament and foresees the possibility of judicial intervention to invalidate legislation where it involves flagrant abuse of power (threats to human rights, removal of judicial review, etc.)  . Considering that not so long ago, Lord Hoffman in R v Secretary of State for the Home Department ex parte Simms and O’Brien  had declared that “Parliamentary sovereignty means that Parliament can, if it chooses, legislate contrary to fundamental principles of human rights. The Human Rights Act 1998 will not detract from this power. The constraints upon its exercise by Parliament are ultimately political, not legal," it seems that this judicial view may take a longer time to find root and flourish.
The Devolution Acts  enabled the creation of the Scottish Parliament, National Assembly for Wales and Northern Ireland Assembly; giving them inter alia the power to legislate on issues related to their areas of competence. The Acts themselves had built in safeguards for the ultimate sovereignty of the central government, however it would be very difficult to justify an interference of the Westminster Parliament in the devolved areas where they have their own elected assemblies and governments. The history of devolution shows that while the central government might have preferred and tried to hold on to “UK-wide" sovereignty, the will of the people living in Wales, Scotland and Northern Ireland have created the necessity for devolution and transfer of sovereignty.
Perhaps the most hard-to-accept challenges to the parliamentary sovereignty were the outside factors: the European Council with European Convention on Human Rights (ECHR) and most importantly the European Union.
ECHR and HRA 1998: The atrocities witnessed during WW2 made it imperative that individual rights and liberties were given supra-national protection. ECHR entered into force in 1953 and UK enacted the HRA in 1998, which enabled individuals to address breaches to their rights in national courts, instead of applying to the European Court of Human Rights if they were not able to find remedies in the national legal system. While the HRA 1998’s mechanism of “declaration of incompatibility" does not automatically invalidate the Acts found to be in breach of Convention rights, it does in effect ask the government to respond, limiting the lengths legislation can go to.
European Union and ECA 1972: UK’s 1973 accession to the European Economic Community (EEC) was enabled by the European Communities Act (ECA) 1972. ECA 1972’s most important effect in limiting the sovereignty of the parliament was that Acts of Parliament would have to conform to EEC Treaties and the decisions of the European Court of Justice (ECJ). Even before UK’s membership to the EEC, ECJ had ruled that there was “ a new legal order of international law" that determined the effects Treaty of Rome in the domestic law  and that EEC law had priority in case of a conflict between national law and the Treaties  . The most significant portrayal of these were seen in the Factortame case  where the ECJ ruled that “a court which in those circumstances would grant interim relief, if it were not for a rule of national law, is obliged to set aside that rule" and the House of Lords, in return, agreed that the courts had a duty to uphold EU law over national law when delivering their judgment. In the Thoburn  case, Lord Justice Laws explained that not all Acts of Parliament are of equal importance, ECA 1972 as a “constitutional statute" is more important than “ordinary statutes", and as such cannot be held to implied repeal: constitutional Acts have to be expressly repealed by the Parliament. This view has served to further limit on the Parliament at least in the procedural sense of repeals.
Like the other countries in the world, the United Kingdom does not and cannot live in an isolated vacuum. As time goes on, changes in the global and internal political and economic arenas inevitably affect the way countries are governed. Looking internally, people in Wales, Scotland and Northern Ireland had clearly demonstrated that they wished to distinguish their own identity over the UK identity. On the global side, WW2 experience necessitated the formation of a supra-national institution which member states would surrender some of their sovereignty to, and in return this institution would bring them together, prevent wars and related economic repercussions. Member states have created the EEC as the common shield, and then gradually empowered it to become today’s EU. One view contends that all these qualifications on the parliamentary sovereignty may be still suspended: “…since, in theory at least, Parliament could repeal any of the laws implementing these changes."  However the fact remains that as explained above, it was actually Parliamentary Acts bringing the limitations. It may be difficult to accept, but such “repeals" will remain as mere theoretical exercises unless and until the people are willing to “re-unite" or get out of EU membership.