An Italian language version of this paper will be published in Diritti Lavori Mercati, 2020, 1.

This paper, which starts from the Epsu judgement of the European Union Tribunal issued in 2019, provides an opportunity to check the extent of the two dimensions of the principle of subsidiarity, i.e. the vertical and horizontal subsidiarity. In doing so, it is necessary to deal with the origin of social dialogue and the role played by the Commission and the Council in that dialogue. A key point stands in the reasons for the Commission's refusal to submit a proposal for a directive implementing a European collective agreement that can be the result of the social dialogue. This paper ends by highlighting that there is not the cancellation of horizontal subsidiarity if one well establishes the "boundaries" of the Commission's motivation.