This paper goes through the evolution of case law on the prohibition of moclifications «in peius» of workers duties, as pro-vide by article 2103, Last pragraph, of the civil code. The study de-als with some hypotheses suggesting that this prohibition could be derogated as well as with the explicít derogation to anide 2103 contained in Act n. 223/1991. The results of the analysis carried out lead the Author to state that case law puts forward a more ela-stic interpretation of the prohibition so as to take into account the worker's interests, which have changed ín accordance with the evolution of the economic and productive context.