Two core functional treaties, the Treaty on European Union (originally signed in Maastricht in 1992) and the Treaty on the Functioning of the European Union (originally signed in Rome in 1957 as the Treaty establishing the European Economic Community), lay out how the EU operates, and there are a number of satellite treaties which are interconnected with them. The treaties have been repeatedly amended by other treaties over the 65 years since they were first signed. The consolidated version of the two core treaties is regularly published by the European Commission.
The two principal treaties on which the EU is based are the Treaty on European Union (TEU; Maastricht Treaty, effective since 1993) and the Treaty on the Functioning of the European Union (TFEU; Treaty of Rome, effective since 1958). These main treaties (plus their attached protocols and declarations) have been altered by amending treaties at least once a decade since they each came into force, the latest being the Treaty of Lisbon which came into force in 2009. Lisbon also made the Charter of Fundamental Rights legally binding, though that is not a treaty per se. The troubled ratification of Lisbon has meant there is little prospect of further reform in the next few years beyond accession treaties, which merely allow a new state to join.
The first deals with common provisions. Article 1 establishes the European Union on the basis of the European Community and lays out the legal value of the treaties. The second article states that the EU is "founded on the values of respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities". The member states share a "society in which pluralism, non-discrimination, tolerance, justice, solidarity and equality between women and men prevail".
Article 3 then states the aims of the EU in six points. The first is simply to promote peace, European values and its citizens' well-being. The second relates to free movement with external border controls are in place. Point 3 deals with the internal market. Point 4 establishes the euro. Point 5 states the EU shall promote its values, contribute to eradicating poverty, observe human rights and respect the charter of the United Nations. The final sixth point states that the EU shall pursue these objectives by "appropriate means" according with its competences given in the treaties.