Company collective agreements apply to all company workers, even if they are not members of the union(s) signing same, with the exception of those workers who, by joining a different trade union, explicitly demonstrate their dissent to the agreement.

Court of Cassation, employment section, judgment no. 26509 of 20 November 2020

With this ruling, the Court of Cassation returns to the issue of the applicability of company collective bargaining agreements.
In the case in point, some employees (drivers) raised court action claiming differences in pay for overtime, to be calculated according to the increases established by the national collective bargaining agreement for that category of workers.
In fact, the employees complained about the inapplicability of the provisions on flat-rate overtime contained in the company-level  agreements, given their express disagreement with these agreements.
The Court of Appeal of Brescia rejected the appeal, observing that the provisions of the company agreements applied, on the basis of express contract, to all the employees, including the plaintiffs, since they did not claim to be members of a different trade union from those who were a party to the agreement. 
The Court of Appeal noted, in fact, that the company agreement “after clarifying that the forfeiture of travel and overtime payments has the nature and effectiveness of a collective agreement” expressly stated that “collective agreements apply to all employees of companies that fall within the scope of the agreements”.
Precisely with reference to the issue of the general effectiveness of company-level agreements, the Court of Appeal comments “the proper purpose of the company agreements stipulated in the specific matter of overtime work performed by drivers assigned to discontinuous tasks: since it may be objectively difficult to define, case by case, what should be considered actual work, with such agreements it is easier to pay the related compensation, adopting, through uniform criteria to be applied to the workers, a lump sum payment”.

The Court of Cassation, with the judgment in question, has confirmed the decision of the court of first instance, reaffirming its orientation according to which “company collective agreements are applicable to all workers of the company, even if they are not members of the trade unions signing, with the sole exception of those workers who, by joining a different trade union, explicitly dissent from the agreement”.
The principle follows an orientation now consolidated within the Supreme Court (Cass. Civ. Sez. Lav. n. 10353/2004; Cass. Civ. Sez. Lav. n. 6044/2012).
The Supreme Court also cites that “the protection of collective interests of the corporate working community and, sometimes, the inseparability of the resulting rules, contribute to justify the subjective effectiveness erga omnes of the company collective agreements, ie towards all workers of the company, even if not members of trade unions (see, among others, Cass. n. 12272/2013, cit.)”.
Therefore, concludes the Supreme Court “the lower court has correctly found that since the applicants were not members of a trade union different from those stipulating the company agreement, then such company-level agreements should apply to them”.