Keywords: Civil Law and Labour Law; Will of the Parties; Contract Integration; Inderogability; Collective Agreement.
Inderogability is a fundamental characteristic of labour law because of its main purpose of protection the weak part of the employment relationship. After the fall of the corporative system, the question concerning the qualification of the collective agreement as a heteronomous source of the individual contract has long catalyzed the doctrinal and jurisprudential debate. To solve this issue, the dialogue between the civil and labor law's doctrines has been fundamental. Specifically, the contribution deriving from the revolution of the contract theory that was taking place in the 1960s and, subsequently, the rewriting of the art. 2113 c.c. have been decisive to solve the problem.