The European Union without EMU: the United Kingdom, Denmark, Sweden and the accession countries

European Monetary Union has the distinction of being among the few EU policies not to require the participation of all EU Member States. This indicates the politically divisive nature of monetary union, as without the possibility of derogation it is unlikely that the Treaty would have been ratified. While in other contentious EU policy areas (such as the Common Agricultural Policy) states were expected to adopt the entire acquis despite reservations about any specific issue areas, monetary union was treated differently in order to ensure that monetary integration would not be derailed due to a small number of recalcitrant Member States. Thus neither Denmark nor the United Kingdom is obliged to adopt the euro in the future.