Why the European Court of Justice is failing us all on climate – the case of the Taxonomy Regulation

14 November 2024 was a grey, rainy day in Luxembourg. But for me, the other members of the Forest Litigation Collaborative (FLC), the claimants and our advocates, the sky over the Court of Justice of the EU was alight with hope and promise. Over two years earlier, we had filed a legal challenge (T-575/22) to the forest management and bioenergy provisions of the EU Taxonomy Regulation, on behalf of Robin Wood and a number of other European ENGOs (Environmental Non-Governmental Organisations). After some protracted case management by the Court, our chance had finally come to explain to five of Europe’s top judges why, in its treatment of forest management and bioenergy, the delegated regulation adopted by the Commission under the Taxonomy was unlawful.

16 months later, on 18 March 2026, the General Court handed down its judgment in the case. By the time I moved on from my work with FLC in November 2025, that hope and promise from the day of the hearing had already been significantly dinted by the Court’s judgment in ClientEarth’s parallel challenge to the bioenergy and bioplastics provisions of the same Regulation. Nevertheless, the Court’s decision to take an extra six months to rule on the Robin Wood case, despite having heard it a week before the ClientEarth challenge, left room for cautious optimism that perhaps its reasoning would be different, at least as far as the forest management components were concerned.

This cautious optimism proved to be unfounded. The Court comprehensively dismissed all twelve of the Claimants’ pleas in law in an unforgiving judgment. The impression given on the day of the judges being attuned and engaged with the Claimants arguments was either a case of gross misjudgment by those of us present, or a strategic act of judicial game-play.

This article does not provide a full analysis of the 84-page judgment. Rather, it draws attention to the Court’s ongoing unwillingness to appraise the legality of the Commission’s delegated acts in terms of the EU’s obligations under the Paris Agreement, even where they have a direct bearing on the EU’s ability to align its GHG emissions with the long-term temperature goal (LTTG). It considers whether the Court’s position and the jurisprudence it relies on remain tenable in view of the Advisory Opinion on climate change produced by the International Court of Justice in July 2025 (the “ICJAO”).

The purpose of the Taxonomy Regulation

The Taxonomy Regulation was adopted in June 2020 to support the EU’s climate obligations and sustainability objectives by defining a classification system for “sustainable economic activities” to “reorient” investment flows and mainstream sustainable finance. It is designed to:

• Help transition the EU’s internal market to meet the goal of “the sustainable development of Europe” under Article 3(3) of the Treaty on European Union;
• Make finance flows consistent with a pathway towards low GHG emissions and carbon-resilient development, as called for in Article 2(1) of the Paris Agreement, and in line with the EU’s commitment to a climate-neutral Union by 2050;
• Provide a harmonised classification system across the EU to “remove obstacles to the efficient movement of capital into sustainable investments in the internal market and to prevent new obstacles from emerging”;
• Help prevent greenwashing.

Article 3 of the Taxonomy Regulation sets out the conditions for an economic activity to qualify as environmentally sustainable. An activity qualifies as such where it meets four requirements:

• 1)    The activity must contribute “substantially” to one or more of the environmental objectives set out in Article 9. These environmental objectives are:
  • climate change mitigation
  • climate change adaptation
  • the sustainable use and protection of water and marine resources
  • the transition to a circular economy
  • pollution prevention and control
  • the protection and restoration of biodiversity and ecosystems.

The requirements for meeting these objectives are set out in Articles 10 to 16 of the Regulation.

• 2) The activity must not significantly harm any of the environmental objectives, in accordance with Article 17. The six environmental objectives listed in Article 9 of the Taxonomy Regulation are the following: (a) climate change mitigation; (b) climate change adaptation; (c) the sustainable use and protection of water and marine resources; (d) the transition to a circular economy; (e) pollution prevention and control; (f) the protection and restoration of biodiversity and ecosystems.
• 3) The activity must meet “minimum safeguards”, namely alignment with the OECD Guidelines for Multinational Enterprises and the UN Guiding Principles on Business and Human Rights, among others.
• 4)  Lastly, the activity must comply with technical screening criteria that have been established by the Commission in accordance with various provisions of the Regulation.

The proceedings

EU rules on standing before the European Court of Justice do not allow NGOs to challenge an EU law directly. Instead, a challenge can only be made in relation to implementing/administrative acts adopted by one of the European Institutions under a primary law. In this case, the Claimants’ challenge was to the European Commission’s exercise of delegated powers afforded to it by the Council and Parliament in the Taxonomy Regulation. Specifically, they challenged the Commission’s Delegated Regulation of 4 June 2021 to supplement the Taxonomy Regulation.

The Delegated Regulation serves two key purposes:

• 1)  First, it defines the Technical Screening Criteria (TSC) for determining the conditions under which an economic activity qualifies as contributing substantially to climate change mitigation or climate change adaptation; and
• 2) Secondly, for determining whether that economic activity causes no significant harm (the “do no significant harm” or “DNSH” principle) to any of the other environmental objectives.
  • To challenge the Delegated Regulation, the Claimants were required first to request the Commission to carry out an internal review based on various grounds of challenge they raised against it (as per Article 10 of the Aarhus Regulation). The Commission issued a decision on the internal review request. It is this Commission decision that the Claimants were able to challenge before the General Court under Article 12 of the Aarhus Regulation.

The Claimants’ arguments re the Paris Agreement and the LTTG

One of the Claimants’ grounds of challenge was that the Commission, in its decision on the internal review, had rejected the argument that the Delegated Regulation infringes Article 2 of the UNFCCC and Article 2(1) of the Paris Agreement. The Claimants argued that the technical screening criteria related to climate mitigation were insufficient to meet the LTTG in Article 2(1) of the Paris Agreement by considering the production of forest bioenergy to produce net GHG emissions reductions, thereby qualifying it as an “environmentally sustainable” activity.

The Court gave the Claimants’ Paris Agreement plea short shrift. Its analysis of the plea began by setting out the relevant jurisprudence to date:

• As established by the case of Council and Others v Vereniging Milieudefensie and Stichting Stop Luchtverontreiniging Utrecht, C-401/12 P to C-403/12 at paragraph 54, the provisions of an international agreement to which the European Union is a party can only be relied upon in support of an action for annulment of an act of secondary EU legislation where two conditions are met: First, where the “nature and the broad logic of the international agreement” do not preclude it and, secondly, where the content of the agreement appears to be “unconditional and sufficiently precise” (see the judgment at paragraph 444);
• Therefore, only when both of these conditions are met can provisions of an international agreement be relied upon before EU courts as a criterion for the assessment of the legality of an EU act (judgment of 16 July 2015 – Commission v Rusal Armenal, C-21/14 P, paragraph 37). This is referred to as the “general rule”;
• Vereniging Milieudefensie and Rusal Arsenal both state that there are two exceptions to the general rule that provisions of an international agreement can only be relied upon a) the nature and broad logic of the agreement do not preclude it, and b) where the contents of the provision are unconditional and sufficiently precise. The first exception is where the EU intends to implement a particular obligation assumed in the context of that international agreement; the second is “where the EU act at issue refers explicitly to specific provisions of those agreements” (Rusal Arsenal, paragraphs 40-41);
• However, the Court has previously clarified that “those two exceptions were justified solely by the particularities of the agreements that led to their application”;
• The conditions for reliance on provisions of international agreements in a request for internal review brought under Article 10(1) of the Aarhus Regulation are the same as for any other case brought before the EU courts.

The Court’s analysis of the general rule for the direct effect of international law provisions

The Court took the view that the general rule for a provision of international law to have direct effect within the EU legal order was not met as regards Article 2(1) of the Paris Agreement. This view rested on its earlier judgment from October 2024 (a month before the hearing of the Robin Wood case) in the Mobility package case (judgment of 4 October 2024, Lithuania and Others v Parliament and Council (Mobility package), C-541/20 to C-555/20, paragraphs 1037 to 1040).

In that case, the Court stated that Article 2(1) “did not appear, as regards its content, to be unconditional and sufficiently precise for it to be relied on directly in order to challenge the lawfulness of an act of secondary EU law” (Robin Wood, paragraph 446). This led the Court in Robin Wood to decide that the same reasoning applies to the provisions of the UN Framework Convention on Climate Change (UNFCCC), and that “[s]ince one of the conditions referred to in paragraph 444 above is not fulfilled, it follows that, contrary to what the applicants claim, those provisions of the UNFCCC and the Paris Agreement do not have direct effect and therefore, in principle, may not be relied on by the applicants to challenge, in the context of the present proceedings, the lawfulness of the contested decision…” (Robin Wood, paragraph 447).

This reasoning has several weaknesses. First, the Court in the Mobility package case performed only a very high-level analysis of the character and applicability of Articles 2 and 4 of the Paris Agreement. The analysis occupies two short paragraphs of a judgment spanning 272 pages. This undoubtedly reflects the argument’s peripheral status in the case; out of the seven Member States bringing the claim, only Bulgaria chose to argue this point.

Consequently, the Court’s consideration of the point is extremely limited. It noted that parties to the Paris Agreement “may comply with their obligations in the manner and at the speed to which they agree” … and concluded that “[c]onsequently, Articles 2 and 4 of the Paris Agreement do not appear, as regards their content, to be unconditional and sufficiently precise for them to be relied on by the Republic of Bulgaria in order to challenge the legality of Regulation 2020/1055” (Mobility package, paragraphs 1039-1040).

Secondly, as can be seen above, the Court in the Mobility package case used equivocal language – “does not appear” rather than making a firm, definitive statement about the character of Article 2(1). Arguably, therefore, it is not a firm rule that the General Court is required to follow when the point is taken in a subsequent case.

Thirdly, the reasoning ignores the special character of international climate change agreements. The causes of climate change are multifarious – fossil fuel extraction, fossil fuel-based power generation, deforestation, transport emissions, ecosystem and biodiversity decline, food production, industrial processes and manufacturing, to name but a few. The causes are common to most States, but not to all – small island states do not generally produce fossil fuels, for example.

Even where the causes are common, the scale and nature are different from one State to another. The mitigation actions appropriate to address each cause therefore vary. As the financial means of States also vary considerably, and given the principle of common but differentiated responsibilities (CBDR-RC), no international climate change agreement can set down universal mitigation actions, nor precise timescales applicable to all State parties within which certain mitigation actions must be taken.

Consequently, on the basis of the Court’s analysis, no provision of international climate change agreement, by its very nature, could ever have direct effect in EU law. Given the acknowledged urgency of tackling climate change, that reasoning needs to be challenged.

The Court’s reasoning on the two exceptions to the general rule

The Court noted that the two exceptions arose in the context of disputes related to international trade law, and specifically the World Trade Organisation Agreements. It further stated that the exceptions “were justified solely by the particularities of the agreements that led to their application” (paragraph 448). Despite the UNFCCC and Paris Agreement being arguably a unique brand of international agreement with particular features that make the direct application of some of their provisions necessary to the achievement of their objective, the Court decided that they do not fall into either one of the exceptions.

As regards the first exception, the Court reasoned as follows:

• The jurisprudence indicates that it is insufficient for the EU act under challenge to merely mention the international agreement in its preamble. Rather, it is “necessary to be able to deduce from the specific provision of EU law contested that it seeks to implement into EU law a particular obligation stemming from the [international agreement in question]” (paragraph 449);
• The claimants had not identified a provision of the Delegated Regulation that was “specifically aimed at implementing, in the legal order of the European Union, a specific obligation resulting from Article 2 of the UNFCCC and Article 2(1) of the Paris Agreement” (paragraph 450);
• The UNFCCC and the Paris Agreement “merely set out objectives and general rules, but without defining any specific means”.  It goes on to cite the sustainable finance flows objective in Article 2(1)(c) of the Paris Agreement but fails to mention the LTTG in Article 2(1)(a). Both agreements allow a “broad discretion” to the parties, including the EU “for the definition of detailed rules for their implementation”. In view of this broad discretion, the Court found that the Commission did not, in adopting the Delegated Regulation, intend “to implement specific obligations arising from Article 2 UNFCCC or Article 2(1) of the Paris Agreement” (paragraph 453).

This reasoning presents similar concerns to the Court’s position on the general rule for direct effect. On the basis of that reasoning, however strong the EU’s commitment to the Paris Agreement and to ensuring the LTTG goal is met, that goal, enshrined in Article 2(1) of the Agreement, could never be directly applicable in EU law because the EU, and all parties, necessarily has discretion as to the measures it takes to align its emissions with the LTTG. This position is difficult to reconcile with the ICJAO’s explicit characterisation of climate change as an “urgent and existential threat” and of all States having legal obligations to mitigate it, both under the climate change agreements and through customary international law.

The Court’s reasoning on the second exception contains a significant error. As it correctly states, for the second exception to apply, the EU act under challenge must refer “directly and explicitly to the specific provisions of the international agreement in question” (paragraph 454). The Court goes on to repeat that the Claimants failed to identify a specific provision of the Delegated Regulation that “refers directly and explicitly to Article 2 of the UNFCCC or Article 2(1) of the Paris Agreement”. This, however, is missing the point.

The purpose of the Delegated Regulation is to add flesh to the bones of the parent regulation, the Taxonomy Regulation. The Taxonomy Regulation makes clear that its purpose is, in part, to implement the EU’s obligations under the Paris Agreement. Recital 24 states, for example, that “[a]n economic activity that pursues the environmental objective of climate change mitigation should contribute substantially to the stabilisation of greenhouse gas emissions by avoiding or reducing them or by enhancing greenhouse gas removals. The economic activity should be consistent with the long-term temperature goal of the Paris Agreement.” Article 2 defines the term “climate change mitigation” as “the process of holding the increase in the global average temperature to well below 2°C and pursuing efforts to limit it to 1,5 °C above pre-industrial levels, as laid down in the Paris Agreement”. The definition is thus expressly tied to Article 2(1) of the Paris Agreement. Article 10(1), meanwhile, enacts the intention of recital 24 by setting down the conditions for an economic activity to qualify as “environmentally sustainable”. It provides:

“An economic activity shall qualify as contributing substantially to climate change mitigation where that activity contributes substantially to the stabilisation of greenhouse gas concentrations in the atmosphere at a level which prevents dangerous anthropogenic interference with the climate system consistent with the long-term temperature goal of the Paris Agreement through the avoidance or reduction of greenhouse gas emissions or the increase of greenhouse gas removals…”

Given that the important link with the Paris Agreement is made clear in the parent regulation, there is no need for the Delegated Regulation to repeat the exercise. The fact that the Delegated Regulation only contains one reference to the Paris Agreement (on page 332 – a reference which the Court seemed to overlook) is not probative of whether the conditions are met for the second exception to apply.

The Court seems to half-accept the point, as it “notes” in paragraph 456 that the Taxonomy Regulation does contain various references to the Paris Agreement. This is where the error arises, however. The Court states that “although that regulation makes a number of references to the Paris Agreement (see recitals 3, 11 and 24 and Articles 2(5) and 10(1) of that regulation), only recital 3 contains an explicit reference to a specific provision of that agreement, namely Article 2(1)(c)…” This is incorrect; both Articles 2(5) and 10(1) refer directly to the LTTG which is Article 2(1)(a) of the Paris Agreement. The Court’s lack of understanding of the LTTG and the Paris Agreement is concerning in times of an existential climate crisis.

Given the express references to Article 2(1)(a) of the Paris Agreement in two articles of the Taxonomy Regulation, there is good reason to believe that the second exception should apply, thereby giving Article 2(1)(a) direct effect in EU law.

The impact of the ICJAO

The ICJ’s Advisory Opinion on State Obligations on Climate Change (ICJAO) had not been published when the Robin Wood hearing took place, preventing its reasoning from reinforcing the Claimants’ arguments on the relevance of the Paris Agreement to the Court’s assessment of the legality of the Delegated Regulation. On the other hand, the ICJAO had been in the public realm for eight months at the time that the judgment was handed down on 18 March 2026. Nevertheless, there is no mention of it in the Court’s consideration of the Claimants’ arguments relating to the Paris Agreement. Either the five judges had not read the ICJAO, or they took the view that as it had not been raised directly in argument, it was not a matter for them to consider.

Would the outcome be different if the ICJAO was considered by the Court, either the General Court or the Court of Justice on appeal? There are grounds to believe that it would.

The ICJAO makes plain that, in view of its consequences, climate change poses an “urgent and existential threat” (paragraph 73). The need for urgent action by States is highlighted by the fact that the “risks and projected adverse impacts and related loss and damage from climate change will escalate with every increment of global warming” (paragraph 83). Similarly, the urgency is evidenced by the scientific consensus that “there is a “rapidly closing window of opportunity to secure a liveable and sustainable future for all” and “the choices and actions implemented between 2020 and 2030 “will have impacts now and for thousands of years” (paragraph 87). While the duties found by the ICJ under customary international law do not depend on the Paris Agreement having direct effect in EU law, the ICJAO considers that the provisions of the Paris Agreement and UNFCCC that start with “shall” are legally binding obligations. These include:

• The duty in paragraph 4(2) UNFCCC to adopt national policies and put in place measures to mitigate climate change through limiting anthropogenic GHG emissions and protecting and enhancing GHG sinks and reservoirs.
• The obligation in Article 4(1) of the Paris Agreement for Parties to put in place and maintain “successive nationally determined contributions” (NDCs), and to pursue domestic mitigation measures aimed at achieving the objectives of the NDC. The relevance to the Taxonomy Regulation is that the ICJAO makes clear the following:

1. The requirement that “[t]he content of a party’s NDCs must, in fulfilment of its obligations under the Paris Agreement, be capable of making an adequate contribution to the achievement of the temperature goal” of limiting warming to 1.5 degrees (paragraph 242).
2. Each party’s discretion in the preparation of its NDC is therefore “limited”. The stringent due diligence duty applies both to the preparation of the NDC (paragraph 245) and to the selection and implementation of the domestic mitigation measures designed to fulfil it (paragraph 252-253).
3. Each Party must make “best efforts” in aiming to ensure that the domestic mitigation measures it pursues fulfil its NDC, and these measures must be “reasonably capable” of achieving the Party’s NDC . Adopting legislation such as the Taxonomy Regulation is one type of domestic mitigation measure that a party can take (paragraph 253). It follows that the EU is obliged to ensure that the Taxonomy Regulation, and delegated acts adopted thereunder, are “reasonably capable” of achieving the EU’s NDC, which itself must be aligned with the LTTG.
4. Domestic mitigation measures must cover activities carried out by private actors (paragraph 252). This also makes the Taxonomy Regulation particularly relevant as its provisions are aimed at the economic activities of private entities as much as public sector ones.

The ICJAO also makes clear that the duty to cooperate applies to UNFCCC and Paris Agreement obligations (paragraph 183). Arguably, if certain parties’ legal systems refuse to accord direct effect to the key mitigation provisions of the Paris Agreement and the UNFCCC, that duty to cooperate will be significantly undermined. For these various reasons, if the EU courts (or any other domestic court of a party to the Paris Agreement) refuse to give Article 4(2) UNFCCC and Articles 2(1) and 4(1) of the Paris Agreement direct effect in the domestic legal order, this would appear to conflict squarely with the ICJ’s position in the Advisory Opinion.

Although the Claimants did not argue that Article 4(1) of the Paris Agreement has direct effect, this is an important point that needs to be taken before the Court of Justice, as that is the article that provides Parties’ obligations to take action to meet the LTTG in Article 2(1).

Conclusion

Very few cases before the General Court have broached the question of the applicability of provisions of the Paris Agreement in the EU legal order. Even when they have done, the argument has been made somewhat timidly. A striking similarity between the Robin Wood taxonomy challenge and the Mobility Package case is that the respective arguments on the Paris Agreement were the last, or almost the last, of the Claimants’ pleas.

The ICJAO provides a welcome and necessary opportunity to change this, and to embolden cases taken to the General Court and to the Court of Justice relating to climate change. Whether it proves to be the decisive factor in persuading the court that Article 4(2) UNFCCC and Articles 2(1) and 4(1) of the Paris Agreement have direct effect remains to be seen. Sooner or later, however, as the climate crisis becomes even more acute, the time will undoubtedly come when the Court will have to accept that the EU’s internationally-derived climate obligations are directly applicable law in its legal system.

Where there is no doubt is that until this is the case, the Taxonomy Regulation will fail to meet its stated purpose, and the EU will be highly unlikely to meet its obligations under the Paris Agreement. By deeming the Claimants’ twelfth plea unarguable in Robin Wood, the General Court has failed to fulfil its task of ensuring the Delegated Regulation is consistent with the parent regulation.

Crucially, the judgment does not ensure that economic activities claiming to make a substantial contribution to climate mitigation are, in practice, aligned with the LTTG. Despite its stated aim of tackling greenwashing, the result of this and other related legal challenges, is a Taxonomy Regulation that carries a sizable hole in its integrity.