The Aarhus Convention's Relevance for Climate Litigation Through the Lens of KlimaSeniorinnen

Against the background of the widespread failure of states to address the climate crisis, litigation is increasingly seen as a key tool for shaking public authorities into action (e.g., Eckes 2021; KlimaSeniorinnen, paras 412, 420-422).1 Showing that they have standing, however, is one of the most difficult hurdles for litigants to overcome when turning to the judiciary to ask for better protection from the climate crisis. Litigants, both individuals and (environmental) associations explore various avenues and frameworks that allow them to access courts for this purpose. In April 2024, the KlimaSeniorinnen judgment by the European Court of Human Rights (ECtHR) paved the way for a new role of associations within climate litigation against public authorities.

KlimaSeniorinnen (KS) was the ECtHR’s first climate case. The ECtHR was also the first international court to rule on a climate case. And, likely encouraged by national judges paving the way, the ECtHR did so boldly, finding Switzerland in breach of Articles 8 and 6 ECHR, for not having adopted adequate national climate measures and denying the association KlimaSeniorinnen access to justice, respectively. When developing its novel approach to the standing and victim status of associations in climate cases, the ECtHR referred extensively to the Aarhus Convention, an international treaty that highlights the role of environmental associations in protecting the environment. Despite this strong reliance on the Aarhus Convention, the ECtHR negated the general applicability of this treaty to climate litigation in a side-comment, arguing that its scope and aim does not cover the issues commonly raised within climate litigation (KS, paras 494, 501), effectively drawing a line between environmental and climate litigation.

Thus, in this post, we develop and defend the significance of the Aarhus Convention for general emission reduction cases, i.e.‘mitigation target cases’, against states, contrary to the ECtHR’s claims, and show that such a clear distinction between environmental and climate litigation cannot be drawn. For our argument, we engage with the different legal frameworks of the European Convention on Human Rights (ECHR), the central human rights treaty in Europe, binding on all 46 Contracting Parties, including all EU Member States but not the EU; the Aarhus Convention, the central treaty promoting democracy in environmental matters, binding on 47 Contracting Parties, including the EU; and to a more limited degree EU law. We draw on climate cases before national courts, case law of the European Court of Justice (ECJ), the ECtHR and the Aarhus Convention Compliance Committee (ACCC).

KlimaSeniorinnen: the Exceptional Nature of the Climate Crisis and Standing in Climate Litigation

In KlimaSeniorinnen, the ECtHR recognised the exceptional nature of the climate crisis and also of climate litigation, acknowledging that the latter raises ‘unprecedented issues’ (KS, 414). Harm does not emanate from a specific source and emissions arise from a multitude of sources. The ‘chain of effects is both complex and more unpredictable in terms of time and place' (KS, 417). ‘The sources of GHG emissions are not limited to specific activities that could be labelled as dangerous’ (KS, 418). Moreover, the tensions between short-term interests and ‘intergenerational burden-sharing’ are particularly strong in the context of the climate crisis (KS, 420). Therefore, what is needed in terms of interventions are ‘comprehensive and profound transformation[s] in various sectors’ (KS, 419). As such, the climate emergency demands from courts and judges the reconsideration of certain aspects of established case law in the field of environmental protection, including prominently the opportunities for associations to defend in court their members’ rights that are affected by the climate crisis and (potentially) breached by the (in)action of states.

Associations often struggle to meet the standing requirements for direct actions relating to climate or environmental policy. This is the case before the CJEU (e.g., C-321/95 P, Stichting Greenpeace v. Council), as well as national courts (e.g., Switzerland, Poland, Germany). Traditionally, this has also been the case before the ECtHR (e.g, Greenpeace e.V. and Others v. Germany; Besseau and Others v. France; Yusufeli İlçesini Güzelleştirme Yaşatma Kültür Varlıklarını Koruma Derneği v. Turkey). However, in KlimaSeniorinnen, the ECtHR explicitly ‘tailored’ its approach on victim status and standing to give effect to the important role of associations for the effective defence of individuals’ interests (KS, 489). Distinguishing between victim status and standing, the ECtHR gave associations – in the climate context – standing as representatives of individuals whose rights are or will allegedly be affected, even if the association cannot itself meet the requirements of victim status (KS, 498). Importantly, associations do not have to establish victim status of its individual members (KS, 502). This new approach is also a pragmatic way of bundling floods of potential individual cases before they reach the court, which likely improves the evidentiary and legal foundations of these cases, while protecting the democratic contribution that civil society can make. The Court emphasised that this role of associations of helping individuals to be able to effectively assert their rights is also recognised by the Aarhus Convention (KS, 490).

Between Reliance and Dismissal: the ECtHR on the Aarhus Convention

Recognising the importance of litigation for climate protection, and especially the role of the public and organisations hereby, is indeed a central aim of the United Nation Economic Commission for Europe (UNECE)’s Aarhus Convention. At its core, the Aarhus Convention explicitly recognises a right to a healthy environment, and seeks to involve the public, and particularly environmental associations, in the protection of the environment (see Recitals 7 and 13). Moreover, the Convention recognises a ‘duty, both individually and in association with others, to protect and improve the environment for the benefit of present and future generations’ (Recital 7; see Barritt on the ambiguous formulation). Provisions of the Aarhus Convention are not only mentioned in the Applicant’s (KS, paras 46, 59, 306, 581) and Intervening Parties’ submissions (KS, para 383), but are also part of the relevant legal frameworks (KS, paras 141-143, 212-214, 221, 232-234) and, importantly, relied on by the ECtHR in its legal reasoning (KS, paras 490-494, 501, 539).

Despite the extensive reliance on the Aarhus Convention, the ECtHR in KlimaSeniorinnen stated explicitly that “the standing of associations in the context of climate-change litigation [...] is not covered by the Aarhus Convention” (KS, para 494). The Court explained this by stressing the “difference between climate change and the more linear and localised (traditional) environmental issues which the Aarhus Convention is designed to address” (KS, para 501). In this way, the ECtHR - in what is basically a side-comment - seemed to negate the applicability of the Aarhus Convention for climate litigation. This restrictive interpretation raises concerns that the ECtHR may intend to reserve its new test for standing to climate cases, i.e. fail to apply it to (other) environmental cases and hence prevent associations from defending their members’ Convention rights also in these cases.

Environmental Matters and Climate Matters: Same Difference?

Possible reasons for this statement of the ECtHR could be the particular focus, objective, and scope of the Aarhus Convention. For one, the Aarhus Convention is intended to facilitate the protection of the environment, as evident from various recitals. While ‘environmental information’ includes information on ‘air and atmosphere’ (Art. 2(3)(a)), which should be understood to encompass information on the climate crisis, the Aarhus Convention does not explicitly mention climate change. This contrasts with the post-Lisbon Treaty on the Functioning of the European Union (Article 191 TFEU), nevertheless, arguably neither specifies other grave and cross-cutting environmental harms, such as biodiversity or habitat loss. However, climate and environmental matters evidently overlap. Moreover, the term ‘environmental matters’ within the meaning of the Aarhus Convention is very broadly interpreted by the ECJ and ACCC (C‑873/19 and ACCC/C/2011/63 Austria), both of which have formal legal authority to interpret the Aarhus Convention, respectively as part of EU law and as such.

At the same time, the ECtHR rightfully acknowledged that the mitigation of the climate crisis affects all areas of life and law and requires deep socio-economic changes that engage all areas of law. It is thus not limited to the law of the environment. And, while other environmental regulation, e.g., dealing with habitat or biodiversity loss or air pollution, may also affect many other areas of life in some form, regulation or the lack thereof in these areas are not in the same way globally connected whereby an action in one place affects everything everywhere else. At the same time, these particularities of the climate crisis with which the ECtHR engages, by no means (!) exclude the applicability of the Aarhus Convention given that other formal requirements of its application are met.

The Aarhus Convention’s Application for Climate Litigation

Generally, the Aarhus Convention focuses on three main pillars that allow the public to take part in environmental governance, which includes various forms of participation, relating to transparency of environmental information, access to decision-making, and access to administrative and judicial procedures. Access to justice obligations under the Aarhus Convention predominately relate to transparency, participation rights, and obligations set out by the Aarhus Convention. The Convention however also entails a broader right of members of the public to enjoy access to justice in order to challenge more general contraventions of the law of the environment as part of its Article 9(3). The chosen term ‘law relating to the environment’ is broad, and the Aarhus Convention Implementation Guide clarifies that it is meant to refer any provision that ‘somehow relates to the environment’, an interpretation accepted both by the ACCC and the ECJ (see above). As such, this definition and thus this broader right of Article 9(3) of the Aarhus Convention can very well encompass climate litigation, including mitigation target cases against states.

Nevertheless, the application of this broader access to justice right for climate litigation cases is limited in two major ways. Firstly, as Article 9(3) Aarhus Convention only allows challenging acts and omissions that contravene “national law relating to the environment”. In other words, some higher-ranking law(s) within the national legal order must exist that creates sufficiently precise rights or obligations concerning climate protection that allow establishing a violation for the Convention to be applicable or invokable. Secondly, the Aarhus Convention generally excludes from its scope acts and omissions of public bodies or institutions that act in a “judicial or legislative capacity” (Article 2(2) AC). Therefore, the Convention cannot be relied upon by litigants if they aim to challenge insufficient legislative acts, or the omission to adopt adequate and sufficient climate protection legislation.

The German Constitutional Court’s Neubauer case of 2021 illustrates some of these limitations in practice. The case concerned a constitutional complaint brought by natural persons, as well as associations challenging both the insufficiency of certain provisions of the German Federal Climate Change Act (Klimaschutzgesetz) in light of minimum emission reduction goals (para 38), as well as more generally the omission of the legislator to adopt further measures that would achieve an adequate reduction of emissions (para 40). This was argued to be in breach of various fundamental rights (para 38) and the constitutional state objective obliging the German state to take adequate climate action (Article 20a GG). Therefore, while a potential breach of applicable higher-ranking national environmental legislation may exist, the litigants aimed to challenge the insufficiency of national legislation and legislativeomissions, which is outside of the scope of the Aarhus Convention. Due to the resulting inapplicability of the Aarhus Convention, the Court could refuse the standing of the involved environmental associations (para 136), and only found the complaints brought by individuals to be admissible (para 91).

National Courts Using the Aarhus Convention in Climate Litigation

Despite these limitations, the Aarhus Convention has been successfully relied on by litigants and national courts in climate litigation. Examples are the Dutch Urgenda case, and the Belgian Klimaatzaak case, whereby the national courts accepted the application of the Aarhus Convention and its obligations to grant adequate and effective access to justice to environmental associations for the challenging of inadequate climate mitigation (see Supreme Court in Urgenda, para 5.9.2 and Brussel’s Court of Appeals in Klimaatzaak, paras 122-123, 135, 146 and 277; on standing under Belgian law, see: Van Durme and Nicotina).

As these two cases illustrate, for the Aarhus Convention to be applicable, the applicants need to challenge not concrete legislativeacts, but rather the general failure of public authorities to take sufficient (non-legislative) action to mitigate the climate crisis and its consequences. In both Urgenda and Klimaatzaak, the Dutch and Belgian states did not have national laws with emission reduction targets at the time the cases were filed and decided. Hence, in both these cases, the associations requested the courts to establish an obligation for the respective government to reduce emissions, and, based on this, the failure of the government to meet this obligation (District Court in Urgenda, para 3.1; Klimaatzaak, para 80). In this way, the challenge did not concern concrete legislative measures or the lack thereof, as the governments could take a variety of measures to mitigate climate change sufficiently, including measures of executive and non-legislative nature (Urgenda, paras 8.2.4, 8.2.7; see also: Eckes 2021). Therefore, one of the two potential formal limitations of the Aarhus Convention was not an issue in these two cases.

Nevertheless, the second limitation could have become problematic for the litigant associations. This is as neither in the Netherlands nor in Belgium existed – at the time of litigating – a higher-ranking national (or constitutional) law that creates an obligation for the national government to mitigate the climate crisis. This is different from the Neubauer case, where the applicants could rely on the German state objective in Article 20a GG. However, both Courts decided to interpret the Aarhus Convention’s concept of ‘national law’ in Article 9(3) broadly to also encompass all rules that in some way form part of the national legal order, which includes the ECHR (Urgenda, para 5.6.1; Klimaatzaak, para 125). As the Courts could rely on the ECHR’s Articles 2 and 8 to create a positive obligation to take action against the threat of dangerous climate change (Urgenda, para 5.9.1; Klimaatzaak, para 125), and the respective governments’ failure to meet this obligation, there existed a breach of a higher-ranking law that formed part of the national legal order.

Therefore, in both the Dutch and Belgium climate cases, the Aarhus Convention was considered applicable, firstly because the challenges concerned more broadly omissions of public authorities, and secondly, because the Courts interpreted the concept of ‘national law relating to the environment’ broadly.

The ECtHR’s Remark on the Applicability of the Aarhus Convention: Wrong and Unnecessary

It follows that the ECtHR’s conclusion in KlimaSeniorinnen that the Aarhus Convention is not applicable to climate litigation is – at least in such a generality – indefensible (see earlier Kelleher). So why did the Court then nonetheless make such a sweeping statement, instead of simply not elaborating on the Aarhus Convention and its (in)applicability?

In KlimaSeniorinnen, the Aarhus Convention seems to be most relevant to the ECtHR in relation to the definition of victimhood, and the consequential question of standing for non-governmental organisations like the Verein KlimaSeniorinnen. Drawing inspiration from the normative choices under the Aarhus Convention enabled the ECtHR to expand its own interpretation of standing and grant associations standing for the purpose of climate litigation before the Court itself (para 501).

However, the ECtHR simply does not have formal jurisdiction to apply or interpret the Aarhus Convention, as the Council of Europe is not a Contracting Party. Therefore, with the comment on the Aarhus Convention’s inapplicability, the ECtHR perhaps simply aimed to clearly delineate the scope, indicating that it was not formally ‘applying’ the Convention, but only taking inspiration for its own reasoning and interpretation of the ECHR for the purpose of climate litigation. The ECtHR’s motivation seems to be pragmatic: avoiding being seen to dictate any particular interpretation of the Aarhus Convention that could later be used against the ECHR’s Contracting Parties or the EU.

Nevertheless, instead of making use of such a generalised, and factually wrong, statement on the Aarhus Convention’s inapplicability for climate litigation for the purpose of delineating its own jurisdiction, the ECtHR could have taken an easier route. In its judgement in Demir & Baykara v Turkey, the ECtHR has in the past accepted the obligation to interpret the ECHR also in light of sources of international law that do not apply directly to the dispute at hand (paras 76ff). The Belgian Court in Klimaatzaak used this case law to stress the importance of the preamble of the Aarhus Convention – which highlights the need to protect also future generations – for the purpose of interpreting the ECHR (para 152). Thus, the ECtHR could have said that the Aarhus Convention does not apply directly to cases before it but was (and should) nonetheless be taken into consideration for its interpretation.

Relevance of the Aarhus Convention for Climate Litigation

We draw two conclusions: First, contrary to the ECtHR’s claim in KlimaSeniorinnen, the Aarhus Convention can be relevant for climate litigation. It most likely does not apply to all forms of climate litigation. However, it can – under certain conditions – be relied on, including in general emission reduction cases against states. Second, even when the Aarhus Convention does not apply due to its formal limitations, the purpose and ‘spirit’ of the Convention remains highly influential in climate litigation. As is well-discussed, the rights of nature and future generations, which are on the receiving end of climate harms, enjoy limited legal protection including procedural protection. However, when the ECHR is read in the spirit of the Aarhus Convention, i.e. when the ECHR is read consistently with a ‘purposive approach’ (Barritt & Kelleher) to the Aarhus Convention, the rights of otherwise sidelined groups are mainstreamed. KlimaSeniorinnen itself is the best example. The international importance of the Aarhus Convention, especially its recognition of the importance of associations and the public as a whole in the protection of the environment guides the interpretation of other relevant national and international access to justice frameworks. Hence, at the very least, the Aarhus Convention provides a weighty argument in favour of standing of organisations. The ECtHR acknowledged and strengthened the relevance of associations in making democratic rights of participation, including through access to justice, effective in practice.

While more explanation would be required for our final point than what we can provide here we would nonetheless like to end by taking a look into the future and flagging the relevance of this discussion for the EU and its Member States. Serious doubts exist as to whether the ECJ’s restrictive interpretation of the standing rights of associations (e.g., C-565/19 P, Carvalho) meet the requirements of either the Aarhus Convention or KlimaSeniorinnen. And, even though the EU – as opposed to the Aarhus Convention – is not a Contracting Party to the ECHR, Member States can be held responsible for not meeting their Convention obligations when the EU violates human rights (Bosphorus). In other words, if the ECJ sticks to its restrictive position on access to justice for associations before EU courts, EU membership may expose Member States to the risk of being held responsible in Strasbourg. KlimaSeniorinnen, Duarte Agostinho, and Careme were only the first three climate cases. Another seven climate cases are pending before the ECtHR and the first climate case against an EU Member State (Müllner v. Austria) has already triggered a discussion of the relevance of EU law as a shield (Eckes, 2024) and the interpretation of the Bosphorus presumption. The contentious issue is whether Member States can claim that the EU both offers human rights protection equivalent to the ECHR and deals with general emission reductions in the EU and that, therefore, the Strasbourg Court should not carry out a detailed review of an individual Member State’s national mitigation target.