After a decision has been made in the European Union, the matter is considered in plenary session if it must be approved by Parliament or if legislation must be drafted as a result of the decision. EU legislation and especially directives often require amendments to national legislation. Decisions are made by Parliament in the normal order. International agreements, including amendments to the EU's Treaties, must be approved in plenary session.
The Speaker's Council may decide to hold a topical debate on an EU matter. The Government can also send Parliament a statement or report on an EU matter that needs to be discussed in plenary session.
The principle of subsidiarity is meant to ensure that decisions are taken as closely as possible to the citizens of the Union. Following the Treaty of Lisbon, any national parliament may object to draft EU legislation by sending a reasoned opinion stating why it considers that the draft in question does not comply with the principle of subsidiarity. This is on the grounds that the draft concerns a matter that should be decided at the national, regional or local level rather than EU level.
The Grand Committee generally evaluates such an issue at the request of one of the special committees. Reasoned opinions must be approved in plenary session on the basis of the Grand Committee's report.