The (European) Economic and Social Committee consists of representatives of organised civil society, and it must be consulted by the Council or by the Commission where the Treaty establishing the European Community (TEC) so provides.
The EESC (or ESC) may be consulted in other cases, as well as by the European Parliament. The EESC may issue opinions on its own initiative.
The relevant treaty provisions on this advisory body are Articles 257 to 267 TEC (in the Treaty of Lisbon Articles 300 to 304 of the Treaty on the Functioning of the European Union; TFEU).
As with the Committee of the Regions, the opinion of the Economic and Social Committee is a mandatory requirement for Community legislation, when provided by the TEC, and the opinion is mentioned in the Preamble of the act.
For a student or researcher digging deeper into a Community act, the opinion is an essential reference.
The Official Journal of the European Union (OJEU) is the prime source for official materials on the European Union.
Far from the hectic pace of public information on the web and daily news reporting, the opinions of the European Economic and Social Committee are published in the OJEU with some delay.
The latest example is today’s OJEU 30.4.2009 C 100, where you find the opinions of the European Economic and Social Committee of the 448th plenary session held on 21 to 23 October 2008.
In other words, official publication takes place about six months after the session. Luckily, you can search the opinions by later sessions on the EESC web page Opinion Search.