While contributing to peace has always been a major objective of European integration, it was only in 1992 that certain values were incorporated into the Maastricht treaty (1992). The current Lisbon Treaty (2007) provides a list of six core values that any Member State or candidate country should comply with: human dignity, freedom, democracy, equality, the rule of law and respect for human rights (including minorities). The EU Charter of Fundamental Rights (2000) is another important document. The average citizen associates the Union mainly with peace, human rights and democracy. The present text also analyses the intellectual grounds for this emphasis on values (the "constitutional" approach of the German philosopher Jürgen Habermas) as well as the difficulty in putting them fully into effect under circumstances like the Greek crisis, the evolution of Hungary (member country) and the relations with Turkey (as a candidate country).