They are all subject to the third stage of EMU, i.e. having accepted the irrevocable fixing of exchange rates, the introduction of the Euro and budgetary discipline, but will benefit from a transition period.

The participation of the rear guard States in EMU is explained by their reluctance to accept that the “Eurozone” is temporarily managed solely by those States, which have introduced the Euro – supported by ad hoc institutions – as they are also affected by any decisions taken. The question of management of the Eurozone – which is of concern to all – has been addressed in pragmatic fashion by the draft Constitution. Only those decisions affecting States with the Euro as their currency are taken in the absence of the rear guard States. Here again,concerns about duplicating legal systems and institutions prevailed.

Historically-speaking, social policy provides another example of differentiation arranged into rear guard of States. John Major did not want the advances in social policy contained in the Maastricht Treaty, however limited, to apply to the United Kingdom. However, he accepted that these provisions would apply to the other Member States in exchange for a Protocol, which left the UK provisionally on the side-line.

Schengen is a good illustration of the theory that it is easier to organise a rear guard than an adv ance party. To begin with, in the 1980s, a majority of Member States established an international framework outside the European Community – without resorting to the Community method, for example by preventing Commission participation in Schengen – in order