A novel feature of the Treaties was that they created institutions distinct from the Member States with the capacity to make law. Such law is known as the secondary law of the EU. It is subordinate to the Treaties, which belong to the primary law of the EU. ‘Secondary EU Law’ explains the principles of conferral and competence, which play an important role in preserving a balance between the powers of the EU and those of the Member States. A leading role is played in the exercise of the EU’s competences by its four main political institutions: the European Parliament, the European Council, the Council, and the Commission.