The EU Constitution contains different categories of competence.
Exclusive Competence
Art. 12 defines competition rules within the internal market, the customs union, common commercial policy, monetary policy for Euro countries, the conservation of marine biological resources under the common fishing policy, and -under certain circumstances- the conclusion of international agreements as exclusive competences.
In these areas the Member States have no right to legislate on their own.
Shared Competence
Art. 13 defines the internal market, agriculture and fisheries, transport, trans-European networks, energy, certain areas of social policy, economic, social and territorial cohesion, environment, certain areas of public health, consumer protection and the area of freedom, security and justice as shared competences. In these areas the Member States lose the right to legislate when the EU legislates.
For research, technological development, and space, the EU may decide on programmes and take action as well as the Member States.
For development co-operation and humanitarian aid the Union will have the competence to take action and conduct a common policy without preventing the Member States from exercising their competence.
Other
Art. 14 gives the EU co-ordinating powers for economic, employment and social policies and allows specific provisions to be decided for the Euro countries.
Art. 15 empowers the EU to act in the field of foreign and security policy. Paragraph 2 obliges the Member States to give active and unreserved support for the Union's common foreign and security policy.
Art. 16 defines industry, education, vocational training and youth, culture, sport, civil protection and improvement of human health as “areas for supporting, coordinating and complementary action”.
The specific legal bases are inserted in the third part of the EU Constitution.