Under the Treaty of Lisbon, codecision officially became the 'Ordinary Legislative Procedure' and the general rule for passing legislation at EU level, covering the vast majority of areas of Union action.
The main characteristic of the ordinary legislative procedure is the adoption of legislation jointly and on an equal footing by Parliament and the Council. It starts with a legislative proposal from the Commission (normally for a regulation, directive or decision) and consists of up to three readings, with the possibility for the co-legislators to agree on a joint text - and thereby conclude the procedure - at any reading.
At first reading, Parliament and Council examine in parallel the Commission's proposal. It is, however, the Parliament that acts first, voting by a simple majority (i.e. a majority of the votes cast) and usually on the basis of a report prepared by one of its committees, in most cases either amending the Commission's proposal or adopting it without amendments. It can also reject the proposal altogether. After the Parliament has adopted its position, the Council may decide to accept Parliament's position, in which case the legislative act is adopted, or it may adopt a different position at first reading and communicate it to Parliament for a second reading. Neither the Parliament nor the Council is subject to any time limit by which it must conclude its first reading.
In very general terms, the second reading in the ordinary legislative procedure follows a similar logic and pattern.
However, when compared to the first reading, there are key differences, in particular as regards the deadlines and the voting procedure in Parliament. Thus at second reading each of the co-legislators has three months, extendible by one month, to adopt its position. As regards the voting majorities in Parliament at second reading, Parliament rejects or amends the Council's first-reading position by an absolute majority of its Members (currently 353 out of 705 votes), rather than by a simple majority as it is the case in first reading.
Conciliation is the third and final stage of the ordinary legislative procedure. The conciliation procedure is opened if the Council cannot accept all the amendments adopted by Parliament at second reading. It consists of negotiations between the two co-legislators in the framework of the Conciliation Committee, with the objective of reaching an agreement in the form of a 'joint text' which then has to be confirmed by both Parliament and the Council.
In practice, a very large proportion of codecision files are now agreed at the first and second reading (including early second-reading agreements: when Parliament approves without amendment the Council's position at first reading). The third and final stage of the procedure, known as 'conciliation', has become the exception and is limited to very difficult files. In the eighth term all files under the ordinary legislative procedure were agreed before the third reading stage.