What constitutes primary law within the European Union?

The concept of primary law within the European Union (EU) is fundamentally tied to the treaties that form the legal foundation of the EU itself. These treaties outline the framework for governance, set out the competencies of the EU institutions, and establish the rights and obligations of member states. Primary law thus consists of foundational legal agreements such as the Treaty on European Union (TEU) and the Treaty on the Functioning of the European Union (TFEU).

In contrast, acts passed by the European Parliament, regulations, directives, and decisions from the European Court of Justice fall under secondary law. Secondary law derives its authority from primary law and is intended to implement, interpret, or detail the stipulations laid out in the treaties. As a result, while these other legal instruments are significant for the functioning of the EU, they do not constitute the primary law that outlines the foundational legal structure and principles of the Union itself.