Thoburn v Sunderland City Council is an important English constitutional law case. It advances the theory that there exists a hierarchy of Acts of Parliament, whereby those Acts affecting "the legal relationship between citizen and State" or "fundamental constitutional rights" form a special and superior category known as "constitutional statutes" and can only be expressly repealed or abrogated by Parliament and therefore immune from the doctrine of implied repeal. Included within this category is the European Communities Act 1972.
In 1994 several statutory instruments came into force whose effect was to bring the United Kingdom into compliance with Directive 80/181/EEC which aims to harmonise the use in the European Community of units of measurement. The directive does not outlaw imperial measures, but sets a timeframe within which they are to be replaced by metric units.
Amongst the measures introduced, the Weights and Measures Act 1985 (Metrication) (Amendment) Order 1994 and the Units of Measurement Regulations 1994 are particularly worthy of mention. Without modifying the basic principle in Section 1 of the 1985 Act that the pound and the kilogram enjoyed parity, the Order specified that the use of the pound as a primary indicator of measurement would be illegal after 1 January 2000 and would be a criminal offence under Section 8 of the 1985 Act. The 1994 Regulations permitted the continued display of imperial measures until 2010 so long as the metric equivalent also appeared alongside in larger characters.
These statutory instruments were adopted on the basis of Sections 2(2) and (4) of the European Communities Act 1972 which authorises Ministers to pass secondary legislation in order to bring the UK into compliance with its obligations under EU law. This is a so-called Henry VIII clause.
The second argument concerned the nature of the authorisation contained in the European Communities Act 1972, what is known as a Henry VIII clause delegating to the Executive a power to amend primary and secondary legislation in order to achieve a certain aim. It was argued that the power to modify legislation only extends to legislation passed at the time the authorisation was made, and not future legislation.
For their part, the respondents argued that so long as the United Kingdom is a member of the European Union, the doctrine of Parliamentary sovereignty whereby Parliament is free to create or repeal any law must be disapplied in relation to matters concerning EU law where the principle of supremacy of EU law as expressed in the judgments of the European Court of Justice in Costa v. ENEL and Van Gend en Loos takes precedence.
In disposing with the second argument Laws LJ took the opportunity to outline a new theoretical constitutional framework within which the competing and seemingly irreconciliable principles of Parliamentary sovereignty and EU supremacy could be accommodated. He began by stating that the exceptions which the common law had in recent years recognised to the doctrine of implied repeal could be explained as forming part of a new class or category of legislative provisions which cannot be repealed by mere implication. There is, in effect, a hierarchy of Acts of Parliament. As he explained:
In this category of "constitutional statutes" Laws identified the Magna Carta, the Bill of Rights 1689, the Acts of Union 1707, the Reform Acts, the Human Rights Act 1998, the Scotland Act 1998, the Government of Wales Act 1998 and the European Communities Act 1972. Such statutes are, because of their constitutional importance, to be protected from implied repeal and, whilst not entrenched in English law, can only be repealed by the express intervention of Parliament. Laws noted that the question of whether the European Communities Act was affected by implied repeal had already been determined by the House of Lords in Factortame. In this case, the Merchant Shipping Act 1988 had in effect impliedly repealed Section 2(2) of the 1972 Act by authorising a discrimination contrary to Community law, but the Lords did not recognise this authorisation as operating as such.
The hierarchy of statutes proposed by Laws is a novel concept in English law, and runs contrary to the principle of equality according to which all statutes are equally susceptible to implied or express repeal.
Thus established, it is the doctrine of Parliamentary sovereignty which necessarily conditions the relationship between English and EU law - only an Act of Parliament can authorise the incorporation of EU law into the English legal system, and the principle of supremacy of EU law must therefore originate from and be authorised by Parliament - an authorisation which is merely temporary. In fact, as Laws added, even if Parliament wished to subordonate the doctrine of Parliamentary sovereignty to the principle of EU supremacy, it would not be able to do it under the terms of English constitutional law. As he explained: "there is nothing in the [European Communities Act] which allows the Court of Justice, or any other institutions of the EU, to touch or qualify the conditions of Parliament's legislative supremacy in the United Kingdom. Not because the legislature chose not to allow it; because by our law it could not allow it."