The work initially deals with the dogmatic justification, the substantive design, and the scope of the principle of equal treatment in labor law developed by national jurisprudence. It also particularly addresses the largely unresolved relationship with freedom of contract. Following this, an examination is conducted of the increasingly numerous specific prohibitions of discrimination, which mostly originate from European law. Their similarities are presented and summarized into a general part of the prohibitions of discrimination. Finally, the author analyzes the relationship between the two different approaches, highlighting their commonalities and differences, and demonstrates how they can meaningfully complement each other in the future.