EU Treaty change: the parliamentary process of bills

Since the UK joined the European Economic Community (EEC) in 1973, there have been six major EU Treaty ratification procedures in the UK Parliament. These concerned the Single European Act and the Treaties of Maastricht, Amsterdam, Nice and Lisbon, all of which amended the original Treaty of Rome to take account of institutional and constitutional changes, new policy developments and additional EU competences. There have been other Treaty amendments – concerning new accessions, for example – which are not considered here. 

Although treaty ratification is strictly speaking a matter of Royal Prerogative, EC/EU Treaty amendments have always been brought into force by means of an Act of Parliament. The passage of the implementing legislation is not formally part of ratification and there is no reference to ratification in the bills, but legislation is necessary if ratification is to proceed smoothly. 

The UK joined the EEC by means of the European Communities Act 1972 and all subsequent bills relating to Treaty change have amended the European Communities Act 1972. Since 1978 the UK Parliament has had to give its explicit approval (by Act of Parliament) to any subsequent treaty or other international agreement which increases the powers of the European Parliament. 

Legislation in 2008 and 2011 specified that EU treaty amendments adopted under the Ordinary Revision Procedure could not be ratified “unless approved by Act of Parliament”. The later Act also provided for a referendum in certain cases where sovereignty was transferred from the UK to the EU.

Of the six Bills linked to EC/EU Treaties, Parliament spent most time on the Maastricht Treaty (41 days), closely followed by the original membership process (39 days). Lisbon came third with 25 days. Lisbon gave rise to the largest number of divisions, although a number of these were not on the Bill itself but concerned government policy in various policy areas relevant to the Lisbon Treaty.