Enhanced co-operation - flexibility in short - refers to activities by groups of EU states smaller than the whole membership, using treaty institutions and laws.
It was written into the Treaty of Amsterdam in 1997 to regulate such activities within the treaty framework. Ireland and other states agreed that subjecting them to the rule of law was preferable to allowing them to fragment the EU by developing outside it.
The Treaty of Nice, under the pressure of a looming enlargement potentially doubling the number of member-states in coming years, has amended these rules in three main ways. It has removed a veto giving any one state the right to prevent such an initiative. It stipulates that at least eight member-states must be involved (a majority now, but not after enlargement).
It also strengthens several of the conditions applying to the use of flexibility and the institutional safeguards to ensure it is not abused.
Flexibility must be consistent with the EU's objectives; used only within the limits of its powers; used only as a last resort after existing mechanisms have failed; remain open to all member-states; deepen its integration; and be approved in most instances by the European Commission, which has responsibility for protecting the treaties' legal integrity.
Flexibility cannot be used in areas over which the EU has exclusive competence, such as the common policies on agriculture, fisheries, trade, the single market, competition and cohesion. This means that most current EU activities are excluded. But it could be used in such areas as border controls, tax, macroeconomic management, environment, employment and social policy. It may now be applied in the EU's Common Foreign and Security Policy, but not to "matters having military or defence implications".
An abiding worry among most EU member-states has been that these provisions could be used to create a two-tier system in the EU, an inner core with more power than the rest. The rules are intended to prevent that happening by ensuring that enhanced co-operation remains open to all states.
Flexibility could be a laboratory for new activities, but inclusively rather than exclusively. Thus it would be a multi-speed rather than a multi-tier system.
Whether these intentions are indeed achieved will depend not only on how well the rules and safeguards are drafted, but on the future course of European integration. That will be determined in the forthcoming debate on the EU's overall shape, culminating in another treaty negotiation in 2004. It will also be affected by whether sufficient resources are made available to the less-developed new member-states to ensure they are able to participate in these initiatives.
On Monday: Foreign policy, security and defence