The European Parliament has its roots in the Common Assembly of the ECSC, which however had no power to initiate the laws and served as an advisory body for the legislative proposals from the High Authority. It had 78 members with dual mandate (members could serve both in the Assembly and their national parliaments) (McCormick, 2011 B, p.204). The Member States themselves chose  how to select the members to the European Parliament: they could hold direct elections or ask their national parliaments to nominate members for the European parliamentary assembly (Shackleton, 2012, p.126).

The Treaty of Rome (1957) increased the European Parliament’s advisory powers. It has changed the way of appointing members and introduced a requirement for direct elections for all the Member States (Shackleton, 2012, p. 126). Nevertheless, the change was slow: the first direct elections took place in 1979. In the meantime, the EU budgetary system was reformed. As a result of these reforms, the Treaties in 1970 and 1975 gave the European Parliament control over the budget: the right to reject the budget and to approve the annual accounts (Shackleton, 2012, p. 128).

Since 1979, the gradual increase in the powers of the European Parliament can be observed. In 1980, in the Isoglucose judgement, the European Court of Justice annulled a piece of legislation as it was adopted by the Council of Ministers without the opinion of the Parliament. The Court thus established the right of consultation (Shackleton, 2012, p. 128). This consultation right requires the Council of Ministers to receive an opinion from the EP before passing a proposal into law. We will discuss the role of  the European Court of Justice in European integration and in the evolution of the European Union institutional setting in the last section.

The Single European Act of 1986 introduced the procedure of co-operation that significantly increased the Parliament’s legislative powers (Cooperation procedure, 2007). The Maastricht and Amsterdam Treaties introduced the co-decision procedure. The Treaty of Lisbon made co-decision an ordinary procedure, which we will discuss again in the following sections (McCormick, 2011 B, p.205).