The 5th COSAC in The Hague on 11-12 November 1991 adopted the first Rules of Procedure. The new rules confirmed that meetings of COSAC should take place every six months during the second part of the Presidency of the Council, taking into consideration the schedules of the parliaments. The rules provided for the possibility of organising extraordinary meetings of COSAC if an absolute majority of the Presidents of the European Affairs Committees were in favour of it. The rules fixed the number of participants per Member State at six, leaving the composition of each delegation up to the Parliaments.
It was furthermore agreed that the Presidential Troika (composed of the current, former and future Presidencies), together with a representative of the European Parliament, should be responsible for proposing topics for forthcoming meetings at the beginning of each Presidency. Decisions on the draft agenda should be taken by the Presidency after having consulted the Presidential Troika and the representative of the European Parliament. The practice of involving the full group of Chairmen of the European Affairs Committees was dropped.
According to the first Rules of Procedure, COSAC was empowered to issue communiqués of the meetings drawn up by the Presidential Troika and the European Parliament. The decision-making process on how to adopt such conclusions was not specified in the rules, but a practice requiring unanimity was established. However, the Presidency was left with the possibility of issuing a message under its own responsibility provided that the Conference could not agree upon a final communiqué. As already mentioned, agreement on the article concerning the change of the Rules of Procedure caused certain difficulties, but it was eventually agreed that consensus was needed for future revisions.
As well as agreeing the rules, the 5th COSAC deliberated on the proposals for a Political Union and an Economic and Monetary Union prepared for the Intergovernmental Conference. The proposals were analysed on the basis of the final declaration of the Assizes.