This work initially presents the practical forms of most-favored-nation agreements (most-favored-nation clauses/collective bargaining most-favored-nation). It then examines the collective bargaining most-favored-nation agreement regarding its validity, based on a dogmatic classification, from both constitutional and statutory law perspectives. Specifically, it investigates the extent to which the collective bargaining most-favored-nation agreement interferes with the freedom of association of trade unions, individual employees, third-party employers, and employer associations, and whether this may result in a legal invalidity of the most-favored-nation agreement. This is also analyzed considering the specific peculiarities in the public service sector. Finally, the impact of the collective bargaining most-favored-nation agreement on labor dispute law is examined.