1. The Members of the Commission

Today the members of the Commission are chosen on the ground of their general competence and European commitment from persons whose independence is beyond doubt.

In carrying out its responsibilities, the Commission is completely independent - the members of the Commission shall neither seek nor take instructions from any Government or other institution, body, office or entity. The members of the Commission must refrain from any action incompatible with their duties or the performance of their tasks.

The Treaty of Lisbon views here separately the High Representative of the Union for Foreign Affairs and Security Policy who is a member of the Commission and conducts the EU’s common foreign and security policy contributing by his proposals to the development of that policy, which he carries out as mandated by the Council. The same shall applies to the common security and defence policy. Thus, the High Representative is mandated also by the Council.

This means double accountability of the High Representative (Damian Chalmers):

In the Commission, the High Representative is one of the Vice-Presidents of the Commission. He ensures the consistency of the EU’s external action. He is responsible within the Commission for responsibilities incumbent on it in external relations and for coordinating other aspects of the EU’s external action. In exercising these responsibilities within the Commission, and only for these responsibilities, the High Representative is bound by Commission procedures.

In the Council, the High Representative presides over the Foreign Affairs Council.

The High Representative is appointed to his office by the European Council, acting by a qualified majority, requiring also the agreement of the President of the Commission. His dismissal is similar - he is the only member of the Commission who is not dismissed unilaterally by the President of the Commission.

From 1 November 2014, the European Commission consists of a number of members, including its President and the High Representative of the Union for Foreign Affairs and Security Policy, corresponding to two thirds of the number of Member States, unless the European Council, acting unanimously, decides to alter this number.
The members of the Commission will be chosen from among the nationals of the Member States on the basis of a system of strictly equal rotation between the Member States, reflecting the demographic and geographical range of all the Member States. This system will be established unanimously by the European Council in accordance with Article 244 of the TFEU.

2. The Principle of Collegiality

The Commission is collectively responsible for all decisions taken and all Commission decisions should be taken collectively. Generally, the Commission decisions should be taken at the weekly meetings of the Commission by the simple majority vote of the College. According to practitioners, meetings of each Commissioner's Cabinet take place two days before the weekly meeting. If there is agreement, it will be formally adopted as an "A" item and no formal discussion on the matter will take place at the meeting. It has been alleged that in reality there is little discussion within the College. (Damian Chalmers)

There are two procedures for taking majority of the Commission's decisions:

1) The written procedure, under which procedure the Commissioner responsible for the relevant portfolio adopts a proposal (a greffe). Thereafter it is expected that the proposal would be approved by the Legal Service and associated Directorates-General after what the proposal would be circulated to the Cabinets of the other Commissioners. Be there no objection, the proposal is adopted as a Commission decision.

The "ordinary" written procedure gives the Cabinets five working days for considering the proposal.

The expedited written procedure must be authorized by the President and the Cabinets are only giveen three working days. (Damian Chalmers)

2) The internal delegation, under which procedure the Commission can delegate a straightforward "act of management" to particular members, at the same time is alleged that it is not clear what constitutes such act, except that it should be an act of management / administrative act. (Damian Chalmers)

The Commission, as a body, is responsible to the European Parliament. Pursuant to Article 234 of the TFEU, the European Parliament may vote on a motion of censure of the Commission. If such a motion is carried, the members of the Commission shall resign as a body and the High Representative of the Union for Foreign Affairs and Security Policy shall resign from the duties that he carries out in the Commission.

3. The Cabinets

The Cabinets lie between the College of Commissioners and the Directorates General. Each Cabinet is the Office of a Commissioner composed of seven to eight officials. The main tasks are: interface between a Commissioner and the DGs, helping the Commissioners to formulate priorities and policies, acting the Commission's eyes and ears, cooperation with other Cabinets in order to prepare the weekly meetings for the College of Commissioners. (Damian Chalmers)