Through ruling no. 134 of 15 July 2025, the Italian Constitutional Court ruled on a key issue for the governance of the energy transition: the constitutional illegitimacy of a regional law introducing an absolute ban on the siting of renewable energy plants.
This ruling aligns with and confirms the position recently adopted by the Regional Administrative Court (TAR) of Lazio – Rome, Section III, in judgment no. 10095 of 26 May 2025, which upheld a challenge brought by our Firm against the rejection of a solar project, based solely on the area’s classification as “non-suitable”(for a detailed overview, see our previous publication dated 4 June 2025).
In that case, the TAR clarified that the classification of an area as “non-suitable” under Regional Law no. 20/2024 of Sardinia and Ministerial Decree of 21 June 2024 cannot result in an automatic ban, but only in a stricter procedural burden within the permitting process. The principle upheld by the TAR – in line with the arguments presented by our Firm – has now received full confirmation from the Constitutional Court.
The new regulatory framework: Legislative Decree 199/2021 and Ministerial Decree of 21 June 2024. Regional autonomy meets its limits: legislative identification is not equivalent to a ban.
Ruling no. 134/2025 of the Constitutional Court declared the illegitimacy of Article 14 of Calabria Regional Law no. 36/2024, which absolutely prohibited the construction of biomass plants with a power exceeding 10 MW within regional and national parks, even with reference to plants already authorized. The subject of the judgement was, therefore, a generalized and retroactive ban, devoid of any procedural balance and not accompanied by an individualized preliminary investigation.
The decision of the Constitutional Court, as well as the ruling of the TAR Lazio before it, measured itself against the new regulatory framework defined by Legislative Decree no. 199/2021 and Ministerial Decree of 21 June 2024, which have profoundly innovated the subject matter, attributing to the Regions the possibility of identifying by law not only the areas suitable, but also those unsuitable for the installation of plants powered by renewable sources.
The Court states, in fact, that "The assessment of the present governmental censure of the Calabrian law now requires this Court to address, for the first time ex professo - given its relevance ratione temporis -, the scope of the recent Ministerial Decree of 21 June 2024, which, precisely by implementing Article 20, paragraph 1, of Legislative Decree no. 199 of 2021, establishes the new principles and uniform criteria for the identification by the regions of the areas and areas suitable and unsuitable for the installation of RES plants".
This power, however, continues the Court, in line with the orientation of the administrative judge, must be exercised in compliance with a fundamental principle: the identification of an area as unsuitable cannot amount to an absolute prohibition, but only to a heightened procedural requirement, to be assessed on a case-by-case basis within the authorization procedure (“a careful reading of the aforementioned ministerial decree shows that the unsuitability of the area , even if declared by a regional law, cannot be translated into an absolute prohibition established a priori, but is equivalent to indicating an area in which the installation of the plant can be equally authorized, albeit on the basis of an appropriate preliminary investigation and reinforced motivation”).
This is precisely the central passage of the reasoning contained in point 7.2 of the judgment, where the Court clarifies that even after the legislative identification of unsuitable areas, the possibility of authorizing specific projects is not excluded. Regional law may identify contexts in which the installation is normally incompatible, but the final decision on the admissibility of the installation must nevertheless be made at the end of a technical investigation, which may - if adequately motivated - also lead to authorization. It follows that unsuitability never takes on, even today, the meaning of a 'preliminary' or 'absolute' prohibition.
According to the Court, this arrangement is functional to guarantee, on the one hand, the enhancement of regional legislative autonomy and, on the other, to avoid the abuse of legislative power for the purposes of mere localist blocking, in contrast with the national interest in the development of renewable sources. In this sense, the ruling shows how the attribution to the Regions of the power to legislate on unsuitable areas cannot be used to introduce a priori bans in violation of the fundamental State principles on energy.
The argumentative coincidence between the Constitutional Court’s ruling and that of the TAR Lazio is evident. Both reject a formalistic and restrictive reading of the legislation on RES and reaffirm the centrality of the authorization procedure as the seat of the balancing of relevant public interests, including environmental protection and the promotion of energy transition. The TAR Lazio had already recognized, in fact, that the Ministerial Decree of 21 June 2024, in the part in which it establishes that the presence in an unsuitable area entails the loss of the public interest in the construction of the plant (Article 7, paragraph 2, letter c), is in conflict with Legislative Decree 199/2021 and with the principles of Law 241/1990. In particular, it infringes Article 20(1)(c) of Legislative Decree No 199, which attributes only indicative - not binding - value to the identification of unsuitable areas and had raised a question of the constitutionality of Sardinian Regional Law No 20/2024 precisely on that basis.
Violation of Articles 3 and 41 of the Constitution: legitimate expectations as a limit to regulatory intervention
In the final part of its judgment no. 134/2025, the Court also extended the declaration of illegitimacy to the Calabrian regional rule that required existing plants to reduce their capacity within six months, under penalty of forfeiting their authorization.
The Court emphasized that private economic initiative can be limited in the name of the environment, as provided for in the reformed Article 41 of the Constitution, but such limits must be proportionate and reasonable. A provision imposing the loss of authorization within such a short timeframe, affecting a single plant that is already operational (the Mercure power plant), is a regulation-measure (“norma-provvedimento” i.e., a rule targeting a specific case) and, as such, is subject to particularly strict scrutiny. According to the Court, that scrutiny is not passed in this case: the rule unjustifiably compromises both the economic freedom of the operator and the position of the workers involved.
A consolidating line of jurisprudence: shared principles
The picture that emerges from the two decisions is thus clear and consistent. The law may identify unsuitable areas, but this identification does not produce automatic exclusionary effects: there remains the need to assess the admissibility of the intervention on a case-by-case basis, by means of a technical investigation and adequate justification. The legislative qualification of unsuitability is therefore not equivalent to a ban.
We are proud to have contributed to a result that confirms the soundness of the legal approach adopted, based on technical rigour, systematic attention and the defence of the principle of legality in the ecological transition.
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Authors of this note are lawyer Massimo Colicchia and Dr. Alessandro Castellini.
For further information or clarifications on the topics discussed in this article, please contact lawyer Massimo Colicchia
Todarello & Partners provides legal assistance on all issues related to the topics discussed in this article. The Firm’s attorneys have relevant experience in the subject matter and in all areas of Administrative Law, regularly assisting some of the largest operators active in the market and representing them before all competent courts.
