The European Union
(EU) comprises 28 member states
. Each member state is party to the founding treaties
of the union and thereby subject to the privileges and obligations of membership. Unlike members of most international organisations
, the member states of the EU are subjected to binding laws in exchange for representation within the common legislative and judicial institutions. Member states must agree unanimously for the EU to adopt policies concerning defence and foreign affairs. Subsidiarity
is a founding principle of the EU.