Laval un Partneri Ltd v. Svenska Byggnadsarbetareförbundet, Svenska Byggnadsarbetareförbundets avdelning 1, Byggettan e Svenska Elektrikerförbundet, Case C-341/05, CJEU, 18 December 2007

Trade unions of workers of a Member State take collective actions, in accordance with the domestic law of that State, aimed at imposing to the service provider of another Member State to sign a collective agreement in favor of workers temporarily posted by that provider on the territory of the first Member State.

Artt. 12 e 49 EC
Directive 96/71 / EC of the European Parliament and of the Council of 16 December 1996 concerning the posting of workers in the framework of the provision of services

Art. 3, of Directive 96/71, relating to the posting of workers in the framework of the provision of services, cannot be interpreted as allowing the host Member State to make the provision of a service in its territory subject to compliance with working and employment conditions that go beyond the mandatory minimum protection standards. In fact, as regards the matters referred to in art. 3, Directive 96/71 explicitly provides for the level of protection which the host Member State is entitled to demand compliance by undertakings established in other Member States in favor of their workers posted to the territory of that host Member State. Consequently, without prejudice to the option for companies established in other Member States to voluntarily sign a (possibly) more favorable collective bargaining agreement in the host Member State, the level of protection guaranteed to workers posted on the territory of the Member State host is limited, in principle, to that provided for by art. 3 unless these workers already enjoy more favorable terms and conditions of employment by virtue of the law or collective agreements in the Member State of origin.