Enlargement of the European Union and "morally imperative", which reflected the desire of the EU to admit these countries as members, even though they were less developed than the Western European countries. Following this Romania and Bulgaria, though were deemed initially as not fully ready by the Commission to join in 2004, acceded nevertheless on 1 January 2007. These, like the countries joining in 2004, faced a series of restrictions as to their citizens not fully enjoying working rights on the territory of some of the older EU members. Bulgaria and Romania are not yet members of the Schengen area; however, their citizens can travel
European Union law 2011 two new treaties, the European Fiscal Compact and European Stability Mechanism were signed among Eurozone countries. In 2013, Croatia entered the EU. However a further crisis was triggered after the UK's Conservative government chose to hold a referendum in 2016, and campaigners for "leave" (or "Brexit") won 51.89 per cent of votes on a 72.2 per cent turnout. Although the European Union does not have a codified constitution, like every political body it has laws which "constitute" its basic governance structure. The EU's primary constitutional sources are the Treaty on European Union and the Treaty on the Functioning of