The Constitutional principle of horizontal subsidiarity and the European Union: the case of the energy communities

Horizontal subsidiarity is articulated into two distinct but complementary dimensions, corresponding to different stages of public action. In its decision-making sense, it is expressed through citizens’ participation in the formulation of public policies: an involvement that strengthens the legitimacy of collective choices and integrates representative mechanisms with instruments of participatory democracy. The implementation dimension, on the other hand, concerns the active role of civil society in carrying out decisions, managing services, and concretely caring for the general interest. In this second case, the relationship between citizens and the administration takes the form of structured cooperation, based on equal and non-competitive logics, according to the model of shared administration. Thus, alongside participation in deciding, there is participation in doing, which constitutes the distinctive feature of horizontal subsidiarity in its fullest form.

While the decision-making dimension of horizontal subsidiarity finds some degree of acceptance in Union law, the implementation dimension remains largely excluded. The model of shared administration, in which citizens and administrations cooperate in the pursuit of the general interest, is still foreign to the legal framework of the Union, which continues to regulate relations between public and private actors according to schemes inspired by competition and contractual reciprocity. Administrative activity therefore remains firmly anchored to a synallagmatic paradigm, which marginalizes any collaborative perspective. In this context, horizontal subsidiarity tends to assume a reductive meaning: not as an instrument of effective cooperation between institutions and citizens, but as a procedural corrective aimed at compensating for the democratic shortcomings of the European decision-making system, through mechanisms of consultation, listening, and civic participation. Its main function appears to be that of strengthening the legitimacy of European institutions, ensuring greater closeness to civil society, rather than promoting structured forms of co-management of goods and services of general interest.

However, a sectoral analysis makes it possible to identify signs of discontinuity with respect to this general framework. The energy sector, in particular, offers a privileged laboratory for observing the emergence, at the legal level, of models that integrate an implementation-oriented conception of horizontal subsidiarity. The transition towards a decentralized and climate-neutral energy system requires, in fact, the direct and structural involvement of citizens not only in the policy-making phase but also in their implementation.

From this perspective, the regulation of energy communities marks a decisive step in the process of opening the European legal order to the paradigm of shared administration. The legal definitions of REC (Renewable Energy Communities) and CEC (Citizen Energy Communities), contained respectively in RED II and the IEM Directive, expressly include local authorities among the actors entitled to participate: a significant element, considering that the legislation not only allows for their involvement but actively encourages it, requiring Member States to provide regulatory support measures and to strengthen institutional capacities. In this way, energy communities fully take shape as instruments of shared administration, in which citizens and administrations cooperate stably in the production and management of energy, generating environmental, economic, and social benefits in the relevant territories. Ultimately, these are mechanisms that formalize the first significant expression of implementation-oriented horizontal subsidiarity, based on co-design and co-responsibility between public and private actors.

In line with the path set by European regulatory evolution, Decree-Law No. 57/2023 amended the Third Sector Code, including among activities of general interest those aimed at the production, storage, and sharing of renewable energy for self-consumption. This intervention established full compatibility between the status of energy communities and that of Third Sector entities, paving the way for the application, in the energy sector, of the shared administration tools provided by the TSC. RECs established in the form of Third Sector Entities can now both participate in collaborative processes promoted by administrations and constitute their project outcome, giving rise to public–community partnerships aimed at sustainable energy development and the promotion of territorial cohesion.

An emblematic example in this direction is provided by the Municipality of Rome, which has recently adopted a specific regulation to govern co-design processes for the creation of solidarity-based RECs. The regulation sets out the ways in which Third Sector entities can collaborate with the municipal administration to establish renewable energy communities in the form of TSEs, providing for the granting of public spaces and requiring that the economic benefits generated be allocated to social purposes.

Thus, while it is true that, within the European Union context, the “implementation” dimension of horizontal subsidiarity still struggles to gain full recognition, the regulation of energy communities represents a noteworthy exception. It is no surprise that this exception has arisen precisely in the energy sector, an area in which the Union has long required active citizen involvement to achieve the strategic objectives related to the energy transition. Through energy communities, in fact, the European legal order appears to have gone beyond the boundaries of “decision-making” subsidiarity, venturing—albeit indirectly and perhaps not entirely consciously—into the still little-explored territory of implementation-oriented subsidiarity. An evolution primarily driven by the transformative impulse of the European Green Deal.

The generative impact of energy transition policies on the Italian legal order provides clear evidence of this: the “irritation”—to use Luhmann’s terminology—produced by European law has triggered a process of redefining the material scope of application of the Third Sector Code. From this perspective, the energy sector today emerges as the main European laboratory for the application of the principle of “implementation-oriented” horizontal subsidiarity, with significant transformative effects on national legal systems.