This paper points out the questions involved by the abrogation of article 47 d. Igs. 29/93 about unions representativeness. In the absence of legal rules, a re-solution recently adopted by the ARAN (public agency for collective bargaining) has introduced a new standard system to estimate the trade unions representati-veness. The analysis emphasizes critically the rejection of one of the most relevant previous standard, that is that based on the result of the election by public workers. As a consequence, only trade unions membership and their territorial diffusion are now regarded as relevant standards. The study goes into the effects and the legitimacy of this resolution, it emphasizes the doubts on the validity of unilateral decisions on this matter, supporting as a result the definition of a new system of legal rules.