This working party composed of member states experts from the capitals (thus not from the permanent representations in Brussels; source) was formally set up by the Council on 25 February and is regarded by the Council as part of the major changes of its working structures in Justice and Home Affairs (JHA) after the Lisbon Treaty ratification.
COSI will have the task to
facilitate, promote and strengthen coordination of operational actions of the authorities of the Member States competent in the field of internal security. (Article 2)Citing from Article 6 of the Council decision, the European Journal remarks that
[w]hereas the committee is required to report its activities to the Council, the Council solely is required to “keep the EP and national parliaments informed.” Hence, such committee will not be subject to a proper parliamentary control.The scope of the work of the committee looks pretty broad, including a number of controversial security issues discussed in the member states and the EU.
From the summary of discussions of the first COSI meeting we learn that one of the tasks of the committee could be to deal with mutual assistants of member states in case of terrorist attacks as well as in case of natural or man-made disasters (cf. Article 222 TFEU).
Other fields of activity concern "the exchange of personal data for law enforcement purposes", "counter-terrorism measures", "PNR" (Passenger Name Records), all topics on the agenda before the summer, as well as the plan for an EU "internal security strategy" which the Commission wants to propose after the summer of 2010. In this regard, the committee is also interested in the co-operation of the EU internal security agencies CEPOL, Eurojust, Europol and FRONTEX whose representatives can be allowed to participate in COSI meetings.
This new committee looks like one of the new major players in the EU's internal security policies on the side of the EU governments - and I hope the European Parliament and national parliaments will be able to counterbalance its weight in the years to come.
Supplement: In the Council search you can find, for example, the latest agendas or summary of discussions in which COSI is mentioned.
Supplement 2: 16 member states have issued their comments regarding the tasks that COSI should take over. Unfortunately, the documents are only partially public so you don't see which country has sent which questionnaire.