A declaration annexed to the Treaty on European Union, which came into force in 1993, states that it might be possible to review the classification of Community acts with a view to establishing an appropriate hierarchy between the different categories of act. The main purpose of such a hierarchy would be to enable the law-making authority to concentrate on policy aspects of particular issues rather than on questions of detail. It would dictate the shape of the Community decision- making process by ensuring that instruments of constitutional status were subject to more restrictive procedures (such as adoption by unanimous vote, augmented qualified majority, and assent) than legislative instruments, which are themselves subject to less flexible procedures (for example, the co-decision procedure) than implementing instruments (for instance, the institutionalized delegation of powers to the Commission). The subject was addressed in 1990 during the early discussions on the possibility of incorporating the co-decision procedure into the Treaty. The underlying idea was to avoid an over-rigorous procedure being applied to certain acts of secondary importance and thereby prevent the legislative machinery becoming congested. In 1991, during the negotiations on the Treaty of Maastricht, the Commission proposed introducing a hierarchy of norms and a new system for classifying Community instruments (treaties, laws, secondary or implementing acts), but failed to overcome the problems posed by the different national legal traditions. The subject has been raised again in the European Convention, which was set up in December 2001 with the task of drafting a constitution for Europe. With the signatory in October 2004 of the Treaty establishing a Constitution for Europe, we have a pyramid of Community acts that simplify the overlapping series of European Treaties and Protocols