Within a few days, both at the Italian level and on the international legal plane, important steps forward have been made on the front of the legal response to the most serious danger hanging over humanity and the planet, an "existential threat": that represented by human-induced global warming and the associated environmental disasters. In both cases, the protagonists were judicial bodies: the International Court of Justice (ICJ) and the Italian Court of Cassation.

1. The Advisory Opinion of the ICJ

On 23 July 2025, the ICJ published the long-awaited advisory opinion on states' obligations regarding climate change and the legal consequences arising from the violation of such obligations. The issue had been referred to it by the United Nations General Assembly in 2023, on the initiative of a broad coalition of states led by Vanuatu, one of the micro-states of the Pacific threatened with survival due to rising sea levels, a consequence of human-induced climate change. The initiative, which was started years earlier by a group of university students, had gradually gained the support of numerous countries, as well as the backing of NGOs and scientists from around the world, until it reached the General Assembly. More than a hundred states appeared before the Court to present their views, and the judges examined the opinions of numerous scientific bodies, primarily the Intergovernmental Panel on Climate Change (IPCC).

The Court issued a highly articulated opinion, spanning 140 pages, to which are added the individual or joint separate opinions of various judges. While agreeing with the final text (all points were decided unanimously), these judges wanted to emphasise aspects that appeared less prominently in the text on which the general consensus crystallised.

1.1. Specific and general international obligations

Probably, the most crucial point of the opinion lies in the recognition that the international norms that deal directly with the issue of climate change (namely, the 1992 United Nations Framework Convention on Climate Change and its Protocols, in particular the Kyoto Protocol and the 2015 Paris Agreement on limiting greenhouse gases to a level that does not lead to a global temperature increase of more than 1.5 degrees above the 1990 level) are not a separate sector of international law (lex specialis), but an integral part of it, and must therefore be applied in light of other relevant principles, customs and conventions. Such principles and norms include the principle of equity, also towards future generations, the principle of good faith cooperation between states, the prohibition of causing significant damage to the natural environment, the prohibition of causing damage in the territory of another state, the sustainable development principle, the principle whereby states have common but differentiated responsibilities and respective capabilities, the precautionary principle and the rules on state resposibility for wrongful acts. The Court also highlighted that climate change is addressed also in a set of treaties on environmental issues (for example the treaty against desertification or those to counter the destruction of the ozone layer), in the convention on the law of the sea (which requires states not to pollute the oceans, including the seabed), in human rights treaties (in particular in the provisions on the right to life, health, housing and a healthy, clean and sustainable environment). This position implies that even states that have not acceded to the Framework Convention on Climate Change and the Paris Agreement – one above all, the United States – are required to comply with this set of rules and are internationally liable for their violation in the event that failure to comply with their obligations causes significant damage to the environment, or results in a significant increase in greenhouse gas emissions.

1.2. The general obligation of due diligence

The advisory opinion affirms in a clear and unequivocal manner the binding nature of the mitigation and adaptation obligations derived from this set of principles, customs, and treaties. Whether they are obligations of result, obligations of conduct, or "programmatic" obligations, the commitment of states must be rigorously assessed. Governments do not enjoy any discretion in this area, with a strict principle of "due diligence" applying. In other words, states must take their commitments to mitigate climate change-related risks (by reducing their emissions) and adapt to its consequences very seriously, in particular by adopting their respective national greenhouse gas reduction plans (Nationally Determined Contributions - NDCs), which must be progressively ambitious and effectively monitored, and by taking all legislative, administrative, budgetary and other measures dictated by the best science and derived from international commitments. Even states that are not parties to the Paris Agreement, for example, in order to comply with their duty of due diligence, must duly consider the decisions of the Conferences of the Parties (COPs) to the Framework Convention on Climate Change and the Paris Agreement. Other criteria that complement the due diligence parameter are prior consultation with other states before undertaking activities that may cause an increase in emissions or impact the efforts of other countries, the obligation to conduct serious environmental impact analyses, and respect for the precautionary principle whereby, States should not refrain from or delay taking actions of prevention in the face of scientific uncertainty.

1.3. Protecting marine ecosystems and safeguarding human rights

The opinion addresses the obligations of states to protect the marine environment, given the importance of the oceans in mitigating the consequences of the greenhouse effect and its impact on marine ecosystems. Particular obligations are owed to states that risk losing parts of their territory due to rising sea levels - another consequence of global warming. The Court also states that the possible submersion of the territory does not necessarily entail the extinction of the state.

Of particular importance is the section of the opinion relating to the relationship between climate change and human rights, where it highlights the duty of states to protect "climate refugees" and underlines how the right to the environment is a "precondition" for the enjoyment of human rights and "inherent" to them (although judges Bhandari and Aurescu observe that the Court could have gone further and recognized that the right to a healthy, clean and sustainable environment has become part of customary law). The obligation to combat climate change through mitigation and adaptation measures is therefore an integral part of the obligations that states have undertaken to protect human rights.

1.4. State responsibility in the event of wrongdoing

After clarifying the binding nature at various levels for all states in the fight against human-induced climate change, the Court rules on the responsibility of states under international law and the obligation of reparation incumbent upon them in the event of non-compliance. Here too, in its opinion the Court rejects the idea that only states parties to certain specific conventions (in particular, the Paris Agreement) can be held responsible for not having done enough to reduce greenhouse gas emissions causing the greenhouse effect and contain the effects of climate change: the duty to prevent, mitigate and adapt to this global phenomenon derives from customary norms and conventional obligations involving all states. The specific obligations and forms of responsibility referred to in the Paris Agreement do not exclude the possibility that the general rules of international law on state responsibility for wrongful acts may apply in relation to other violations of their international obligations or that other specific accountability régimes may apply. The Court, of course, recognises the complexity of the analysis required to attribute responsibility to one state or groups of states for a phenomenon as complex as anthropogenic climate change; moreover, anthropogenic factors have accumulated over the decades. However, scientific observations are now sufficiently precise to allow, on a case-by-case basis, a detailed reconstruction of which behaviours of state or private actors have contributed to causing damage linked to global warming and thus to establish their international responsibility on a legal basis, while excluding forms of strict liability. Moreover, some of these violations, relating to obligations that states have towards the entire international community (for example, the obligation to avoid significant damage to the environment by limiting greenhouse gas emissions), lend themselves to being addressed on the initiative of any state, not just the states most directly harmed by such conduct (or lack of conduct) (erga omnes obligations). A wide range of reparation measures is therefore envisaged, which, depending on the circumstances, may require the cessation of unlawful conduct and the guarantee of non-repetition, the restoration of the situation to its previous state or monetary compensation for the damage caused, or other forms of reparation for non-material damage.

1.5. An opinion in line with recent regional decisions: the Advisory Opinion 32/2025 of the Inter-American Court of Human Rights

The Court's opinion, although not binding, marks a historic shift in the way international law addresses the threat of global warming, as it moves from considering state mitigation and adaptation policies as essentially optional and based on voluntary commitments, to considering them a fundamental obligation, enforceable at the initiative of any other international actor.

The Court has likely exceeded what many states expected. The subject is indeed dense with political, economic, industrial and strategic implications. There was a risk that the Court would take an ambiguous path between affirming international legality and recognising the economic and geopolitical interests of the most influential states. Despite some shortcomings (highlighted by some judges in their separate opinions), the judges unanimously chose a path of great clarity on the legal level, radically changing the status of international environmental law, which had been hitherto considered a field of predominantly soft law.

The opinion aligns with some recent judgments and opinions of the main regional human rights courts. In particular, in 2024 the European Court of Human Rights (ECtHR) had ruled that for a contracting state (Switzerland), the failure to implement commitments on greenhouse gas reduction constituted a violation of the right to private life of certain categories of people (Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, Grand Chamber, judgment of 9 April 2024, application no. 53600/20). In 2023, the Inter-American Court of Human Rights (IACtHR) extensively dealt with the importance of the right to a healthy environment in the case of La Oroya Population v. Peru, judgment of November 27, 2023, Series C No. 511. Above all, in 2025, the Inter-American Court issued an important opinion (at the request of Chile and Colombia) on the climate emergency and human rights (AO 32/25, 29 May 2025). In addition to affirming the existence, at a global level, of a veritable environmental emergency linked to global warming, the Court identified an "enhanced due diligence" as the response that states must give to this situation. The right to the environment (connected to Article 26 of the American Convention on Human Rights) is linked, according to the IACtHR, to the states’ peremptory obligation (jus cogens) of not causing irreversible damage to the climate and the natural environment. To protect nature and its ecosystems from the multiple threats caused by humans and, in particular, by global warming, it is necessary to recognise the legal subjectivity of Nature and its components (including human populations). The rights to environmental democracy, science, and information (on environmental and climate issues), as well as consultation and participation in environmental decisions, and the rights of environmental defenders, must also be recognised.

2. ... And the Italian Court of Cassation confirms that even in Italy, companies can be held accountable for failure to comply with climate commitments

In 2023, Greenpeace Italy and the Recommon association, along with other individuals living in areas particularly vulnerable to climate change risks, sued ENI, the Ministry of Economy and Finance, and Cassa Depositi e Prestiti (the latter two as reference shareholders of ENI). In their view, they had failed to meet their obligations regarding the achievement of internationally recognised climate objectives. In particular, ENI, an energy multinational based in Italy, according to the applicants, despite having committed itself in its code of ethics to respecting human rights and the objectives of the Paris Agreement, had pursued a strategy not in line with the IPCC's indications. Its decarbonization plan for 2050, in addition to not providing for the total abandonment of fossil fuels, envisages a reduction in emissions of only 35% by 2030 and foresees an increase in hydrocarbon production in the coming years. In addition, ENI, like other oil companies, would finance media campaigns and lobbying actions aimed at minimising the climate emergency.

The Court of Rome had previously been involved in a similar dispute, but one directly concerning the Italian government. On that occasion, it found its absolute lack of jurisdiction: the Italian judiciary did not have the power to scrutinise the laws of Parliament and the other measures taken by the government, even if incompatible with its international commitments, since this would have involved undue interference by the judiciary with the executive and parliamentary powers. Referring to this precedent, ENI and the other defendants were preparing to challenge, among other things, the jurisdiction of the Italian judiciary. To settle this point, the applicants filed an appeal for regulation of jurisdiction before the Court of Cassation. The Court of Cassation essentially had to determine whether, in this case, the claim for compensation should be excluded due to a lack of jurisdiction.

The response from the Court of Cassation, adopted on 18 February 2025, was published on 21 July 2025. According to the United Sections of the Court of Cassation, civil division, the case against ENI is different from the one previously brought against the Presidency of the Council of Ministers, since the request for ascertainment of the tort and compensation for damage concerns a private entity (ENI and its main shareholders), not political bodies. The claim is, in fact, based on Article 2043 of the Italian Civil Code (liability for tort - Articles 2050 and 2051 of the same code, relating to non-contractual liability caused by dangerous activities or by things in custody, are also cited). The alleged tort consists of ENI's failure to comply with the commitments it undertook regarding the reduction of climate change emissions, which responded to the obligation introduced by the 2015 Paris Agreement.

This Agreement is binding not only on states, but also on private entities operating within them, so there is no point for ENI in appealing to its corporate autonomy. Failure to comply with these commitments constitutes a violation of the European Convention on Human Rights (ECHR), Articles 2 (right to life) and 8 (right to private and family life), as can be inferred from the case law of the ECtHR in the case of Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, as well as Articles 9 and 41 of the Italian Constitution, which enshrine the protection of the environment with prevalence, if necessary, over the business choices of economic operators, or even Articles 2 and 7 of the EU Charter of Fundamental Rights (CFREU).

The Court of Cassation has therefore resolved the jurisdictional issue preliminarily raised by Greenpeace and the other applicants, stating that the court can proceed on the merits of the dispute, since it is not being asked to rule on political or legislative choices of the state, but rather to ascertain whether a private company (albeit largely owned by public shareholders) has failed to comply with its legal obligations. It will be up to the tribunal to determine whether the obligations on climate-altering emissions set by the Paris Agreement also apply to private parties and whether there has been an actual violation of Articles 2 and 8 ECHR or 2 and 7 CFREU, and also whether the claim for compensation for tort damage brought by the applicants deserves to be upheld.

The order of the Supreme Court also confirms the territorial competence of the Italian judge to deal with the dispute. In fact, not only are the applicants claiming a violation of their right to life and private and family life (which includes health, quality of life, personal relationships, etc.) have their domicile in Italy, but also the company accused of causing such damage with its policies has its main headquarters in the Country. It is therefore irrelevant to oppose that the emissions are produced mostly in foreign states, since the legal links identified are sufficient to establish the jurisdiction of the Italian judge.

3. Conclusions

Thanks to the Court of Cassation's decision, even in Italy, climate change litigation can gain momentum, which in other European countries has already led to significant results, compelling governments and companies to revise their policies to combat greenhouse gas emissions in a more ambitious manner. This approach receives further impetus from the ICJ's opinion, which, a few days after the publication of the Court of Cassation's order, confirms the binding value that the Court attaches to international environmental law to combat climate change, whose norms take on a "structuring" value with respect to the international legal order.