EU Treaties are international agreements signed and ratified by sovereign states. The EU is, therefore, a creation of international law. However, it is increasingly treated by scholars as distinct from international law and is starting to resemble a national system in its scope and complexity. ‘On the origin of treaties’ explains how the EU treaties may be amended, which is more difficult than amending secondary EU law, and the processes of joining and leaving the EU. Finally, it considers the general principles of law and fundamental rights that bind the EU’s institutions and member states.