Transforming the Rule of Law in Environmental and Climate Litigation: Prohibiting the Arbitrary Treatment of Future Generations

Abstract

This article maps the shared legal anatomy of climate and environmental lawsuits, in which plaintiffs claim protection for future generations before domestic or international courts. By closely analyzing the litigation strategies of plaintiffs and the inquiry of courts, the article argues that these proceedings revolve around structurally similar legal standards across domestic and international jurisdictions, which correspond to five normative requirements flowing from the rule of law: namely, respect for human rights, certain quality of law requirements, prohibition of arbitrary exercise of governmental powers, non-discrimination, and access to justice. The cross-jurisdictional analysis shows that courts appear to be increasingly willing to protect future generations against arbitrary treatment by present-day decision makers. The article appraises whether such an intergenerationally sensitive reinterpretation of the rule of law could help to change the short-termist paradigm of environmental and climate law.

1. Introduction

Lawsuits that are challenging states’ environmental or climate policies in the name of, or with reference to, future generations and their long-term interests are becoming a transnational trend. This pattern of litigation, referred to here as ‘future generations lawsuits’, includes climate litigation,¹ as well as environmental and biodiversity litigation,² and transcends continents, legal systems, and legal cultures. At the same time, these proceedings are highly diverse: they are launched under various substantive legal bases, by different kinds of plaintiff, against different respondents, and they seek different types of legal remedy before various national and, increasingly, international fora. Notwithstanding these differences, the lawsuits appear to share some structural similarities, which will be the focus of this article.

The analysis zeroes in on domestic and international lawsuits, in which the interests of future generations are invoked in order to claim and establish new or enhanced obligations for states in relation to posterity in the context of setting their environmental or climate policies. The aim of this cross-jurisdictional comparative analysis is to map the common legal architecture of future generations litigation by sketching the doctrinal ‘frontlines’ of such lawsuits. In other words, the article will focus on the legal doctrines based on which plaintiffs claim, and courts increasingly appear to afford, protection for long-term interests and needs across domestic and certain international jurisdictions. These demands, as I will argue, correspond to a handful of structurally similar legal safeguards that are derived from the imperative of the rule of law.

I use the term ‘rule of law’ in a broad and normative sense, as a guarantee against the state's arbitrary exercise of power over the individual.³ This article will show that the shared legal anatomy of future generations litigation lies in five more concretely defined requirements of the rule of law: (i) respect for human rights, (ii) certain quality of law requirements, (iii) prohibition of arbitrary exercise of governmental power, (iv) non-discrimination, and (v) access to justice.⁴ The cross-jurisdictional analysis will examine the ways in which these safeguards play out in the context of future generations litigation, where courts appear to be increasingly willing to reinterpret rule of law obligations in order to protect future generations against arbitrary treatment by present-day decision makers. In such an extremely rapidly proliferating field as future generations litigation it is not feasible to include every relevant decision in this article. The cases under review, therefore, have been selected to provide examples of the argumentative solutions of a wide range of jurisdictions, thereby shedding light on some cross-jurisdictional trends in the adjudicative practice.

The central claim of the article is that states are increasingly held accountable by courts – thus far primarily by domestic fora – when decisions by governments or the legislature undermine the vital environmental interests of posterity in an arbitrary manner. I understand arbitrariness here as the capacity of present-day decision makers to benefit from the inherent intergenerational asymmetry between those whose conduct generate long-term risks for the stability of the climate and the ecosystems and those who bear the devastating consequences of such actions. State policies that inflict harm on future generations in full awareness of the potentially catastrophic long-term impacts revealed by robust scientific insights can be viewed as unreasonable⁵ and irrational⁶ – and, even more fundamentally, as ‘arbitrary’.

As a caveat, the scope of this analysis is confined to examining legal claims that seek to protect the ‘environmental’ interests of future generations – namely, a safe and liveable planet and climate for our descendants. Needless to say, posterity has a host of other interests, and their liveable future is not only jeopardized by the climate and ecological crises but also by a range of other threats, including nuclear wars, pandemics, and artificial intelligence. The doctrine of intergenerational equity has also been invoked in contexts outside the ‘environmental’ or ‘climate’ protection discourse – concerning, for instance, the accumulation of sovereign debts⁷ or the sustainability of pension schemes.⁸ This article, however, will only examine the ways in which states can be held liable for undermining intergenerational needs when designing their environmental and climate measures.

The rule of law framework adopted in this article serves both analytical and explanatory functions. On the one hand, it provides an anchor for the comparative analysis; this analysis seeks to make sense of the trends in a booming field that may, at first glance, appear to feature divergent legal arguments and even ad hoc judicial developments tied to the specificities of respective jurisdictions. On the other hand, the framework also helps to explain some of the drivers of these lawsuits and explores some wider, more systemic implications that such lawsuits may bring to the current paradigm of environmental and climate governance. The analysis will ultimately appraise whether an intergenerationally sensitive ‘revolutionary’ reinterpretation of normative rule of law guarantees can help to change the short-termist paradigm of the domestic decision-making process that has led to and is dominating the Anthropocene.

The analysis is structured in five main parts. Section 2 identifies three layers of connections between the rule of law and the current planetary crises. The interrelations identified here not only demonstrate how the rule of law could be thrown into disarray if critical thresholds that mark ‘the safe operating space of humanity’⁹ were to be exceeded, but also how the concept has played a critical role in producing such planetary risks and how it could be transformed into a means of abating them. Section 3 identifies the main normative obligations flowing from the rule of law, and explains why these safeguards offer an influential point of intervention for courts in various jurisdictions to impose long-term obligations on states. Section 4 turns to specific rule of law guarantees, and maps cross-jurisdictional patterns of mobilising these intergenerational rights and obligations before different national and international fora. Section 5 concludes by appraising the potentially transformative impact that future generations litigation may have for the short-termist paradigm of environmental and climate governance by developing an intergenerationally conscious reading of states’ obligations under national and international law.

2. The Rule of Law and the Ecological and Climate Crises: Three Layers of Interconnections

The epoch of the Anthropocene¹⁰ is marked by humanity's role as the dominant force of change on Earth.¹¹ Our activities and technologies are now capable of fundamentally altering ecosystems and the geochemical cycles of the planet. The last decades have seen an unprecedented environmental and climate crisis that will fundamentally impair the living conditions of future generations – if it remains unabated within a rapidly closing time window.¹² It is now widely accepted that the climate crisis is, essentially, a human rights crisis.¹³ This article will take a step further and argue that the planetary crises challenge the very concept of the rule of law. The multifaceted connections between the rule of law and the planetary risks of the Anthropocene can be depicted through three distinct layers. The first is the most overt linkage, concerning the interdependence of sustaining the rule of law and a stable climate and thriving ecosystems. The second layer, perhaps less obviously, relates to the pivotal role that the rule of law has played in charting humanity's course into the Anthropocene. The third layer, however, highlights that rule of law guarantees, via an intergenerationally sensitive reinterpretation, can also be key in steering humanity towards a sustainable future.

Turning to the first layer, several phenomena attest to a mutual interdependence between securing the rule of law and maintaining a liveable planet. Multiple experts have voiced concerns that democracies and the rule of law will not survive this century if our generation fails to take sufficiently stringent and immediate measures to protect the ecosystems and the climate.¹⁴ Philip Alston, United Nations (UN) Special Rapporteur on Extreme Poverty and Human Rights, warns that poverty fundamentally threatens the rule of law, as massive inequalities between nations may result in ‘climate apartheid’,¹⁵ and that further deprivation stimulates nationalist, xenophobic, and racist responses within societies.¹⁶ Fundamental freedoms will be at risk, even in established democracies.¹⁷ Delayed and ineffective climate action in the present will inevitably force future generations to enact immediate and drastic mitigation measures to halt the catastrophic consequences of climate change. Doing so would equate putting a ‘full brake’ on their lifestyle, which inevitably leads to restrictions on individual freedoms.¹⁸ These include restrictions on personal modes of travel and on consumption of food, water, and energy.¹⁹ Governments may also be forced to declare states of emergency. The German Federal Constitutional Court has also warned that courts may not be able to protect individuals against restrictions of their freedom rights as they would be deemed necessary and proportionate to tackle the climate crises, and therefore lawful under domestic laws.²⁰ This all suggests that, despite their deeply ingrained short-termist horizon, democracies must nevertheless become able to safeguard long-term environmental interests to sustain the rule of law and democracy itself in the long run.

Their interdependence is, emphatically, mutual. Not only do environmental problems frustrate the principles of the rule of law, but a backlash against democracy and the rule of law also virtually always leads to a decline in the normative safeguards that protect ecosystems and the climate. Populist social movements often undermine taking ambitious climate mitigation action and environmental protective measures.²¹ Populist leaders threaten the international rule of law by challenging multilateralism,²² while, at the national level, they often pursue anti- or deregulatory agendas,²³ undermine environmental democracy, including rights related to environmental information and public participation,²⁴ and altogether hinder expertise-based environmental lawmaking.²⁵ Empirical surveys also suggest that greater degrees of commitment to the rule of law raises the stringency of environmental measures,²⁶ provided that this is not met with high degrees of corruptibility, which could offset such effects.²⁷

The second layer of connections between the rule of law and the planetary crisis concerns the genesis of the Anthropocene. As argued in depth by Viñuales, as a social technology the law had a fundamental role in engendering the Anthropocene by regulating and legitimizing the growth-centred economic and industrial system that made it possible for our species to dominate the Earth system.²⁸ The global north has played a pioneering role in mastering both the necessary technological innovations and growth-based capitalism and consumerism that are jointly responsible for the Anthropocene. The right to property, for instance, in its liberal conception as conferring unlimited and exclusionary power on the owner, was a key driver behind developing a growth-based economy, originating from western Europe in the 17^th century.²⁹ Property rights have enjoyed strong protection in democratic legal orders committed to the rule of law.

Sustaining the traditional normative content and contours of requirements flowing from the rule of law perpetuates socio-economic processes that undermine the opportunities for future generations. In particular, the rule of law provides for legal certainty, favouring stable and predictable laws. This requirement can also be utilized to hinder regulatory answers to emerging risks and uncertainties surrounding ecological and climate threats.³⁰ In the same vein, the rigidity of the law often works in favour of the holders of economic power by protecting their ‘right to pollute’ and enabling them to impose externalities on communities within the bounds of often relaxed environmental protection standards.³¹

Moreover, democratic governance is inherently, and systemically, biased against future generations.³² Elected leaders favour immediate economic gains to satisfy their constituencies, whereas minors, and future generations, are disenfranchised. Presentism is thus deeply ingrained in democracy and in our conceptions of the rule of law, which, as argued in this article, has played a vital role in driving humanity into the Anthropocene. Rule of law guarantees, if interpreted as being applicable only between contemporaries, create a system of laws that is inherently inclined to overlook long-term interests and non-human environmental assets. The rule of law is not only anthropocentric,³³ but its traditional understanding is also presentist and, thus, tolerates (if not enables) the necessities of life to be looted from our descendants.

Despite all these shortcomings, the third layer of relevant connections, which is the focus of the remainder of this article, suggests that a potential remedy for the ‘regulatory deficits’ of the Anthropocene³⁴ may also lie in the rule of law. Several fora have become responsive to the grave intergenerational asymmetry between the conditions and possibilities of decision makers living in the present and those who will have to bear the resulting impacts in the future. The last decade has seen a boom in successful future generations lawsuits, where courts were willing to limit governmental freedom of action in adopting policies with harmful future effects through developing intergenerational dimensions for certain rule of law guarantees. This will be explored in the coming section.

3. An Intergenerational Reinterpretation of the Rule of Law

Pleading with the interests of future generations appears to be a useful litigation strategy, which creates a material impact on judicial inquiries in climate and environmental lawsuits.³⁵ The plaintiffs in such cases claim normative guarantees under various domestic and international legal doctrines to protect future generations against arbitrary treatment. In other words, they demand the extending of core rule of law guarantees to posterity, too.

The political ideal of the rule of law³⁶ knows several expressions across jurisdictions, such as Rechtsstaat or État de droit, and has been translated into various more precise political and legal requirements in different legal systems.³⁷ The term is sometimes used to stipulate a set of principles for positive laws,³⁸ to designate the separation of powers,³⁹ or it is invoked in a broad sense to denote the legally regulated nature of certain aspects of state conduct,⁴⁰ the binding nature of relevant international rules,⁴¹ or as a sweeping reference to the system of rules governing a given field.⁴² In this article, by contrast, I rely on the definition used by rule of law scholars proper, which locates the essence of the term in an overarching guarantee against the arbitrary exercise of sovereign powers.⁴³ I will therefore look for judicially enforceable guarantees of the rule of law – that is, safeguards against arbitrariness – in the case law.

Future generations lawsuits deeply resonate with the core idea of (non-)arbitrariness. In an increasing number of judgments, courts attempt to curtail the almost unrestricted ability of governments to favour immediate economic gains by disregarding, arbitrarily, the basic needs and interests of future generations. Arbitrariness is defined here as the ‘uncontrolled, unpredictable and unrespectful’ exercise of governmental power,⁴⁴ which denotes a ‘distinctive form of unreasonable[ness]’.⁴⁵ Domestic laws in which present-day lawmakers use their discretionary leeway to pursue short-term gains while freely ignoring the harmful future ramifications, of which they are clearly aware based on ample scientific warning, are fundamentally unjust, unreasonable, and, in this sense, ‘arbitrary’⁴⁶ in respect of future generations.

Intergenerationally arbitrary decisions may come in many forms, by way of both an action or an omission of the state. The former is illustrated in cases where courts strike down short-termist climate and environmental policies that sacrifice long-term interests for immediate gains.⁴⁷ With regard to the latter, when faced with state inaction to protect environmental assets for the sake of posterity, courts often compel governments to enact protective measures.⁴⁸ In these cases the exact formulation of judicial guarantees of non-arbitrariness is closely tied to national laws and domestic legal cultures and, hence, are varied in nature.

The analytic framework adopted here relies on the rule of law pillars identified by the Council of Europe (CoE) European Commission for Democracy through Law (also known as the Venice Commission), an international independent advisory body dedicated specifically to promoting the rule of law and democracy.⁴⁹ The Venice Commission has developed extensive doctrinal work regarding the normative content and components of the rule of law. Its relevance is not confined to Europe, as the Commission's definition squares with that endorsed by the UN at the global level,⁵⁰ and also resonates with scholarly views coming from a non-Eurocentric perspective.⁵¹ The Commission lists five overarching ‘thick’⁵² (meaning substantive) requirements under the rule of law, which are: (i) respect for human rights, (ii) quality of law criteria, (iii) guarantees of non-arbitrariness, (iv) non-discrimination, and (v) access to justice.⁵³

Notwithstanding certain future-looking policies,⁵⁴ these pillars have largely been enforced under a tacit assumption of contemporaneity, in as much as they pertain to how reigning governments should treat and regulate people living under their rule and power at the given moment. Plaintiffs’ litigation strategies in future generations cases, however, seem to challenge such a presentist conception of the rule of law head-on, and increasingly successfully so. A growing number of courts have been willing to expand the temporal scope of rule of law guarantees into the future, either by enforcing them with regard to the grievances of future rights holders or applying such guarantees to protect current subjects against future risk or harm.

The following section will show how such an intergenerational reinterpretation of rule of law pillars emerges in judicial practice and serves to limit the ability of states to disregard the interests and needs of future generations in an arbitrary manner. In these judicial decisions, rule of law obligations are interpreted in a future-oriented way and thereby impose the following binding obligations on states:

• • respect for the human rights of future individuals (currently living or yet to be born),

• • the quality of law requirement, demanding that national laws capable of interfering with human rights safeguards must meet certain requirements, such as clarity, foreseeability, and specificity;

• • the prohibition of arbitrary use of governmental powers in respect of the long-term interests of posterity;

• • non-discrimination vis-à-vis future generations, prohibiting direct and indirect discrimination against children based on age or birth cohorts; and

• • access to justice: justiciability of legal challenges against environmental and climate policies of governments and granting standing to plaintiffs acting on behalf of long-term interests.

The above pillars denote, in my view, the common legal architecture of many future generations lawsuits. It may be no coincidence that litigation strategies in diverse jurisdictions and under different legal contexts can all be traced back to specific aspects of the rule of law. Indeed, climate governance studies have observed that ‘overarching rules’ can act as vehicles for change and alter the prevailing system of governing climate change.⁵⁵ The rule of law concept appears to be one of those ‘overarching rules’.

Developing forward-looking, intergenerational dimensions for actionable rule of law obligations is a significant legal innovation, which can assist in reimagining the legal order to become more responsive to future threats and to the risk of committing posterity to harmful path-dependencies in the present. A recent study warns, however, that successful legal innovations need to be incremental rather than radical, because of law's preference and need to adhere to past commitments.⁵⁶ This means, in our context, that the creative, ‘imaginative’,⁵⁷ one might even say ‘revolutionary’ interpretation of the scope and content of intergenerational state obligations should also be grounded in well-established norms in order to succeed.

The concept of the rule of law could satisfy such a need for groundedness and continuity. The fundamental role that the ideal of the rule of law plays in every democratic legal system renders its normative components effective and legitimate anchors for courts to develop incremental changes in the understanding of states’ obligations. The combined effects of this reinterpretation may nevertheless be transformative for the enforceability of claims of intergenerational justice. Further, invoking claims based on the rule of law before courts has practical value in protecting the interests of future generations. Many successful landmark judgments attest to the potential of targeting these basic pillars of the rule of law.

Rule of law safeguards thus serve as influential points of intervention. Through novel interpretations, courts can inject a long-term perspective into states’ traditionally short-termist decision making. Applying actionable rule of law guarantees to protect the interests of later generations offers a workable backdoor mechanism to challenge states’ myopic policies, which are otherwise often insulated from judicial review.⁵⁸ If domestic and international courts were to continue to acknowledge the intertemporal dimensions of basic rule of law guarantees, legislatures would be discouraged from passing myopic environmental and climate measures. As a result, invoking the interests of future generations can also help to close the liability gap for inflicting future harm, which is thought to be a potentially significant legal response to the Anthropocene challenge.⁵⁹

Finally, to appraise the practical significance of demanding safeguards against arbitrariness towards future people, we should examine the temporal limits of such litigation strategies. While the basic theory of intergenerational equity is not limited in its temporal scope,⁶⁰ it is important to acknowledge the practical barriers to effective advocacy with regard to interests to be protected in the 22^nd or 23^rd centuries. The temporal reach of such claims appears to be capped by constraints inherent in the methods with which posterity's relevant interests can be defined by courts in a robust (and non-arbitrary) way. As I argue in Section 5, these standards lie in scientific knowledge and soft law instruments. The horizon of our scientific and political attention currently revolves around harm that is likely to arise from human-induced warming by 2050 (that is, within the lifetime of the next generation),⁶¹ or at the end of the 21^st century (affecting the generation that comes after).⁶² Viewed from this perspective, it may be no coincidence that plaintiffs appear to be most successful in claiming rule of law-based protection for future generations when they frame their complaints around the near future.

Having stated that, with the advent of technologies capable of exerting large-scale systemic influence over the climate system, such as geoengineering, it is not inconceivable to imagine a scenario where actions taken today produce harmful effects over centuries from now. Theoretically speaking, nothing precludes claiming guarantees of non-arbitrariness towards posterity even on such a timescale.

4. Limiting Arbitrariness: Litigation Strategies in Future Generations Lawsuits

The overwhelming majority of claims thus far put forward by plaintiffs in future generations litigation seem to fall into one or more of the above-listed five main categories corresponding to the main rule of law guarantees.

4.1. Respect for Human Rights in the Future

The traditional conception of human rights is somewhat presentist, in that safeguards are thought to be applicable only between contemporaries.⁶³ Major international human rights covenants are silent about future individuals and declare jurisdiction over complaints if the rights holder falls within the jurisdiction of the duty bearer,⁶⁴ which arguably requires proximity in both space and time. However, expert proposals have long advocated adopting a more future-oriented stance.⁶⁵ Most recently, the Maastricht Principles on the Human Rights of Future Generations, released in February 2023, set the tone for a new reading of international human rights law, which emphasizes the absence of any ‘temporal limitations’ of the guarantees set forth in major covenants.⁶⁶ This implies that human rights safeguards should be guaranteed for future individuals in the same manner as for those currently living.

The proliferating field of rights-based climate litigation also attests that courts do offer protection for human rights against future harm and/or for those of future individuals in the context of the climate and ecological crises. There are various conceptualizations of relevant violations of human rights across different temporal scales and with regard to different specific rights, leading to divergent lines of judicial inquiry in such cases.

Initially, courts deduced the obligations that states owe to future generations from select human rights, such as the constitutional right to a balanced and healthful ecology,⁶⁷ or to a healthy environment.⁶⁸ The latter has been invoked to advocate the protection of long-term needs and environmental assets in a range of jurisdictions, which include Pakistan,⁶⁹ Brazil,⁷⁰ Hungary,⁷¹ and a state court in the United States (US).⁷² The Supreme Court of Hawaii has even declared a ‘right to a life-sustaining climate system’.⁷³ Other courts are focusing on more general human rights safeguards. Dutch⁷⁴ and Belgian⁷⁵ courts, for instance, have found that the over-lenient climate commitments of their governments violated Articles 2 (right to life) and 8 (right to private life) of the CoE European Convention for the Protection of Human Rights and Fundamental Freedoms (ECHR).⁷⁶

Other jurisdictions define potential claimants more narrowly, and protect only the rights of certain most vulnerable special rights holders, such as children⁷⁷ and Indigenous communities.⁷⁸ Building on its own earlier findings in Sacchi v. Argentina and Others,⁷⁹ the UN Committee on the Rights of the Child, in 2023, defined several specific obligations for states in the context of climate change in its General Comment No. 26.⁸⁰ It remains to be seen whether this document will alter the litigation strategy of child plaintiffs, as an empirical study found that the majority of them did not plead violations of their rights as children but focused on their grievances to be endured later, in their adult lives.⁸¹

Moreover, as a doctrinally distinct category from children's rights,⁸² explicit recognition for the rights of future generations is also gaining ground in human rights discourse. Besides the Maastricht Principles cited above, a central role was afforded to the environmental rights of ‘unborn generations’ in the inquiry of apex courts in Colombia⁸³ and Pakistan.⁸⁴ Even in jurisdictions that remain wary of speaking explicitly about the rights of future generations, future interests do shape the obligations that courts impose on states.⁸⁵ Courts may also conceptualize harmful climate impacts as a violation of the full range of the possible spectrum of rights held by every individual. As famously found by the German Federal Constitutional Court, unambitious greenhouse gas (GHG) reduction measures were unconstitutional because they were leading to a future where ‘practically all forms of freedom’ would be put in jeopardy.⁸⁶

The above conceptualizations of protected rights are closely interlinked in judicial analysis with different configurations of the temporal dimension of relevant human rights violations. One may distinguish four judicial approaches in this respect. Firstly, courts can address violations of human rights that are already taking place. This approach was chosen in the Torres Strait Islanders’ case, in which the lack of climate adaptation measures was deemed an ongoing breach of human rights.⁸⁷

The second, somewhat similar approach adopts a back-casting method focused on competing rights in the present to tackle the conflicting interests of different generations. The analysis of the Hungarian Constitutional Court in its Forest decision is a stark example.⁸⁸ The Court reviewed the constitutionality of an amendment to the Forest Act that would expand the property rights of private forest owners against the general public's right to a healthy environment. Noting the constitutional importance of intergenerational equity, the Court annulled the amendment and afforded protection for the interests of future generations against the resource extraction of the current generation by balancing the right to environment against the right to property.

A similar back-casting logic features in Neubauer, where the partial annulment of Germany's federal climate law was rooted in the anticipated restrictions on constitutional rights (so-called ‘advance interference-like effect’) that the act would have imposed after 2030.⁸⁹ This approach is responsive towards violations that will take place in the more distant future. The Dutch Supreme Court, for instance, declared a violation of rights even though the government's lax mitigation commitments were leading to risks that ‘will only be able to materialize a few decades from now’.⁹⁰

A final option lies in protecting the individual's rights against violations that are inevitable in the short term. The European Court of Human Rights (ECtHR), for instance, protects the right to life and private life against imminent future environmental risks.⁹¹

4.2. The Quality of Law Requirement vis-à-vis Domestic Climate Laws

Domestic laws that may interfere with human rights must meet a certain quality to be compatible with the rule of law. Such a requirement was developed in the most nuanced way by the ECtHR⁹² in requiring that national laws that may interfere with basic rights be ‘sufficiently clear and detailed’⁹³ and ‘foreseeable’⁹⁴ as to their effects on the persons concerned. In the context of climate litigation, these requirements could be invoked analogously to demand that national climate laws include detailed and clear mitigation targets that are sufficiently ambitious to avert drastic climate impacts.⁹⁵ Although such quality of law requirements have not been argued by applicants – though by one intervener⁹⁶ – in the pending climate cases before the ECtHR, national courts have set similar conditions for the quality of climate mitigation laws under domestic law.

In Neubauer, the German Constitutional Court found that the statutory emissions pathway was unconstitutional because it did not specify long-term reduction targets, and therefore offloaded the mitigation burden onto future generations.⁹⁷ The same justification was adopted later by the South Korean National Human Rights Institution in its Opinion on the climate crisis.⁹⁸ Similar specificity requirements were invoked by the Supreme Court of Ireland, which ruled that the government had to ‘give real and sufficient details’ in its National Mitigation Plan,⁹⁹ and also by the United Kingdom (UK) High Court in litigation surrounding the UK Net Zero Strategy. The Court in the latter case required the Secretary of State to give ‘explanations’ for the bases of the Net Zero Strategy under the statutory obligation to ‘set out’ policies for meeting the carbon budget.¹⁰⁰

4.3. Preventing Arbitrary Exercise of Governmental Powers to the Detriment of Future Generations

A distinct pillar of the rule of law embodies safeguards that curtail the state's ability to exercise its governmental powers arbitrarily over the individual. Such guarantees against arbitrariness in the strict sense find legal expression in various formulations of due diligence obligations. These ensure that the interests of future generations are not neglected or overridden even outside the scope of human rights safeguards and requirements for the quality of climate legislation. Duties of care towards the future are rooted in a range of doctrines that are closely tied to the substantive laws of respective jurisdictions and, hence, span a wide variety. Yet, they all aim at curtailing the freedom of the sovereign decision maker to disregard future needs and interests in exercising its executive powers.

Firstly, under the ECHR system, states have a well-established positive duty to take ‘all reasonable and necessary’ measures to prevent interference with protected rights. This duty of care is frequently invoked in climate change lawsuits.¹⁰¹ National courts have already reviewed the legality of domestic climate measures under the doctrine,¹⁰² and concluded that respective governments overstepped the bounds of their discretion under Articles 2 and 8 ECHR in that they failed to demonstrate the required level of care in designing their GHG reduction pathways.¹⁰³ The District Court of the Hague (The Netherlands), in its Urgenda decision, allowed conducting a cost-benefit analysis in discharging such a duty of care. It stressed, however, that costs should be allocated reasonably between present and future generations and that the state has a ‘serious obligation to combat climate change if taking action in the present is predicted to be cheaper’.¹⁰⁴ The Court of Appeal found that the economic and social costs of delayed action strongly warranted taking action in the present.¹⁰⁵

The possible intergenerational aspects of states’ due diligence obligations under international human rights law at the global level and under customary international law so far have been less articulated in either positive law or in international judicial practice.¹⁰⁶ An early exception lies in General Comment No. 26, emphasizing that states do have a ‘heightened duty of care’ towards children and thus have an obligation ‘to set and enforce environmental standards that protect children from such disproportionate and long-term effects’.¹⁰⁷ A major international legal avenue for protecting intergenerational interests lies in the due diligence obligation under customary international law.¹⁰⁸ This is also well reflected in the questions put before the International Court of Justice (ICJ) in the pending advisory opinion proceedings, which ask the Court to clarify the legal relevance of future generations for the content of due diligence obligations under customary and treaty obligations, and with respect to the legal consequences of any violation thereof.¹⁰⁹ Putting future generations more squarely into the due diligence calculus would be an important step with potentially far-reaching implications. Doing so would, for instance, provide further support for states in refusing to grant new fossil fuel projects on account of their expected future emissions.¹¹⁰

Due diligence obligations may also stem from domestic law. In Neubauer, the Court deducted that the German Basic Law imposes on the legislature a special duty of care towards future generations.¹¹¹ Such a duty may also be rooted in civil codes¹¹² or in common law doctrines requiring consideration of the interests of minors.¹¹³ In some jurisdictions there are currently proposals to enshrine a duty of care towards future generations in statutory law.¹¹⁴ States may also be required to exercise care to protect essential ecosystems and natural resources (such as forests or rivers) for the future, under various stewardship¹¹⁵ or guardianship¹¹⁶ obligations.

In some jurisdictions (Ecuador, for example), courts use the Rights of Nature paradigm to safeguard the interests of posterity. Even though the future generations discourse and the Rights of Nature movement may appear, at first, to be distinct and divergent, they share the goal of carving out certain long-term assets from the unfettered discretion and resource exhaustion of states.¹¹⁷ Ecuadorian courts, for instance, prohibited all mining operations in the Los Cedros forest on such a legal basis,¹¹⁸ and opined that any harm that impairs nature is harm inflicted upon several generations.¹¹⁹

Another prominent legal avenue for restricting states’ ability to favour immediate economic gains lies in the public trust doctrine, which appears in the laws of various jurisdictions.¹²⁰ The doctrine imposes fiduciary duties on states under common law, statutory law or constitutional law, and it deems governments to be sovereign trustees, which ought to preserve the trust's assets – natural resources – for its beneficiaries, present and future. The scope of relevant assets varies across jurisdictions,¹²¹ as do the exact requirements for the trustee.

The public trust doctrine has already been applied successfully in environmental litigation to exclude policy choices that arbitrarily impair the needs and rights of future generations.¹²² Scholars have also long advocated pursuing the doctrine in climate litigation through arguing for an atmospheric public trust,¹²³ but it is only recently that courts have picked up such a line of reasoning. In March 2023, Judge Wilson argued in his concurrent opinion, in the Hawai'i Electric Light Co. case, for a public trust obligation to reduce the level of atmospheric carbon dioxide (CO₂) below 350 parts per million.¹²⁴ A few months later, a state court in Montana decided in favour of youth plaintiffs based partly on the doctrine in Held v. Montana.¹²⁵ A number of further climate public trust cases are still pending, including the Juliana case before a US district court,¹²⁶ and those before courts in India, Pakistan, and Hungary.¹²⁷

4.4. Age-Based Discrimination of Minors and Future Generations

In political decision making, future generations are a permanently disenfranchised interest group¹²⁸ whose diverse interests are harmed by myopic laws and policies. There is ample scientific evidence that children born today will experience much harsher climate conditions in their adulthood than experienced by members of previous generations.¹²⁹ The staggering results of a scientific study show that children aged below 10 in 2020 will experience a fourfold increase in certain weather extremes.¹³⁰ In the light of these scientific insights, it becomes obvious that children are already ‘particularly affected’ by climate change.¹³¹ What is more, such studies make it possible to frame disparate climate impacts as discriminatory treatment. One may conceptualize the problem as either indirect discrimination against children on account of their age, or as birth-cohort discrimination, whereby certain children alive today (together with later generations) are more adversely affected than previous cohorts.¹³²

Climate impacts are framed as a violation of non-discrimination towards children and future generations in several cases pending before the ECtHR.¹³³ The problem of birth-cohort discrimination features most acutely in the Duarte Agostinho case, initiated by Portuguese children before the ECtHR against 32 states, on the basis of violating the right to life and to private life in conjunction with the prohibition of discrimination.¹³⁴ They argue that, as a result of the respondents’ failure to adopt stringent mitigation measures, the complainants will experience extreme weather events, which affect their living conditions and health. An essentially similar pleading was put before the Court of Justice of the European Union (CJEU) in the Armando Carvalho case to challenge the European Union (EU) GHG reduction commitments as far too lenient, but failed on procedural grounds because of the claimants’ lack of standing.¹³⁵ Anti-age discrimination claims are also on file with domestic courts in various states, from Italy and Austria to South Korea and Canada.¹³⁶ Hearing a complaint based partly on the non-discrimination clause of the Canadian Charter of Rights and Freedoms, the Superior Court of Justice of Ontario has deemed the ‘adverse effects of climate change on younger generations’ as ‘self-evident’.¹³⁷

4.5. Access to Justice in Future Generations Litigation

Another central issue in future generations litigation concerns the rights of minors to access justice – that is, whether disputes involving scientifically (and politically) loaded environmental and climate policy choices are deemed justiciable by the courts, and whether certain plaintiffs can claim intergenerational standing. Even though climate change disrupts longstanding judicial doctrines in respect of both questions,¹³⁸ there are signs that courts are increasingly open to tackling intergenerational cases on the merits.

According to the Venice Commission, ‘the judicial branch appears to be best placed to protect future generations against the decisions of present-day politicians’.¹³⁹ Indeed, courts often deem such safeguards justiciable, despite pledges mostly being couched in symbolic language. This trend is backed by an emerging scholarly consensus¹⁴⁰ and practitioners’ support¹⁴¹ for judicial intervention aimed at protecting long-term interests when fundamental rights are at stake. The justiciability of conflicting rights and obligations in an intergenerational setting was expressly linked to the rule of law in Urgenda, in which the Dutch Supreme Court stressed that the courts’ mandate to ‘offer legal protection, even against the government, is an essential component of a democratic state under the rule of law’.¹⁴²

In European jurisdictions, the separation of powers doctrine does not usually constitute an insurmountable obstacle to adjudicate cases challenging domestic climate targets.¹⁴³ The approach of courts is far from uniform, though. The first instance court in Klimaatzaak, for instance, found that it was not entitled to set a specific reduction target for the legislature under the separation of powers principle.¹⁴⁴ The appellate court disagreed and compelled the respondents to ensure that Belgium meets its target of reducing GHG emissions by 55% by 2030 compared with emissions levels in 1990.¹⁴⁵ The reach of the political question argument is strongest in some common law countries, having blocked climate lawsuits on the merits in the US and Canada.¹⁴⁶ EU courts have also been hesitant in relaxing strict standing requirements to allow climate claims to proceed.¹⁴⁷

Plaintiffs seeking to establish standing on behalf of generations unborn face challenges rooted in the conceptual difficulty of claiming representation for future individuals.¹⁴⁸ Transgenerational entities¹⁴⁹ such as communities – which include states, tribes and cities, as well as specialized spokesperson institutions¹⁵⁰ – have already succeeded in bringing intergenerational claims to courts.¹⁵¹ Children and youth plaintiffs are the other types of actor who typically have standing; they comprise around a quarter of the claimants in rights-based climate change lawsuits.¹⁵² Some courts have acknowledged the right of youth plaintiffs to claim intergenerational standing,¹⁵³ but many jurisdictions have not.¹⁵⁴ At the international level, children have been deemed to be victims of adverse climate impacts in the future, and thus were granted standing before the UN Committee of the Rights of the Child in a complaint regarding states’ inaction on climate change.¹⁵⁵ The same issue is currently being litigated before the ECtHR with regard to Portuguese children, coupled with the question of whether the children have standing to bring a claim that demands climate action extraterritorially, from 32 foreign states.¹⁵⁶

Domestic courts have mostly addressed the exterritoriality question at the standing stage. Some acknowledge a close link between intergenerational and intragenerational equity, as suggested by various scholars.¹⁵⁷ In Neubauer, the German Constitutional Court recognized the standing rights of complainants coming from Bangladesh and Nepal, although it stressed that the extent of Germany's obligations to prevent future adverse climate impacts abroad are fundamentally different from those owed to its own citizens. It thus found the narrower extraterritorial obligations to have been met.¹⁵⁸ To this extent, this decision may even be placed among the more restrictive jurisdictions.

Intergenerational claims are also raised in class action lawsuits, which are filed by children in their own name and on behalf of future generations. A Canadian court notably deemed the composition of a class to be arbitrary because it involved only residents under the age of 35 in a particular province and excluded inhabitants of other regions.¹⁵⁹ The majority of decisions seems to follow a more restrictive path and bundle the interests of present-day children and future generations only at the local scale – if they all live in the same region or in the same state.¹⁶⁰ Such an attitude expands the temporal horizon of state obligations at the price of confining their geographical scope. This approach fails to consider intragenerational (extraterritorial) grievances – past, present, and future – in concretizing intergenerational obligations.

Such decisions could be criticized for being ‘parochial’¹⁶¹ and even ‘hypocritical’.¹⁶² Indeed, courts of the global north appear to be weary of holding historically high-emitting states accountable for their historical emissions, and they do not compel governments to adopt stricter emissions reduction obligations on account of the widespread damage that such emissions have been (and will be) causing for the historically low-emitting countries from the global south. In a warming world, future generations of different parts of the world will face very diverse climate and environmental futures. We are yet to see whether domestic and international courts will be willing to reflect on these differences and integrate intragenerational equity into their reasoning in future generations lawsuits.

5. Judicial Standards for Detecting Arbitrariness: Science and Soft Law

In operationalizing the legal doctrines surveyed above, courts need some criteria to anchor their analysis concerning the future interests they deem worthy of protection through judicial intervention. Most importantly, they must ensure that their reasoning is not seen as capricious or biased. The legal doctrines I identified above are vaguely defined, open-textured norms, the application of which to particular facts leaves considerable room for judicial discretion. For instance, the concept of due diligence under international human rights law does not entail specific obligations for states,¹⁶³ nor do the public trust doctrine or the right to a healthy environment. Courts therefore need to find substantive benchmarks to appraise the compatibility of sovereign conduct with normative requirements. In doing so, they must devise legal (or technical) standards to measure against the ‘arbitrariness’ of laws and policies or, in other words, their capacity to encroach upon the interests of future generations. Two common argumentative solutions emerge. Courts either refer to scientific knowledge or to goals enshrined in soft law documents to review the merits of short-termist legislation.

Science is often seen as a supplier of objective knowledge in the courtroom,¹⁶⁴ enabling adjudicators to make robust assessments of the magnitude and imminence of future risks. Taking into account robust scientific knowledge is a core requisite for making ‘reasonable’¹⁶⁵ decisions. In this vein, to limit the sovereign's regulatory freedom, domestic courts often rely primarily on scientific reports. In Neubauer, the German Federal Constitutional Court pointed to the results of climate science in finding that the lawmaker exceeded the bounds of its discretion. It stressed that ‘if reliable data suggest that the constitutionally relevant temperature limit might be exceeded, such data must be taken into account’.¹⁶⁶

References to climate science seem to be an almost obligatory accessory of climate litigation judgments. The recommendations contained in the reports of the Intergovernmental Panel on Climate Change have sometimes directly laid the foundation for the reduction targets mandated by courts.¹⁶⁷ The findings of expert organizations are also instrumental in defining the breach of stewardship obligations. In the Amazon decision, the Supreme Court of Colombia referred to scientific reports to support its conclusion that governmental measures were ineffective in combating environmental problems in the region.¹⁶⁸ Similarly, the first instance court in Klimaatzaak referred to the opinion of the Federal Council for Sustainable Development to justify finding a lack of good climate governance, which was one of the grounds for establishing a breach of the government's civil law duty of care.¹⁶⁹

Another cross-jurisdictional pattern shows that courts often use soft law goals and prior policy commitments of the state as a benchmark for assessing whether governments arbitrarily harm the interests of future generations. Such an inquiry was most explicit in the Hungarian Forest decision, in which the Constitutional Court partially quashed an amendment to the Forest Act for contravening principles set out in the long-term National Forestry Strategy. The Strategy had been adopted by the legislature as a non-binding sectoral policy instrument setting out a long-term vision and principles for national forest management. A few years later, the amendment narrowed the powers of authorities to mandate temporal and spatial restrictions on logging for nature conservation purposes. The Court opined that this ran counter to sustainable forest management, as set out in the Strategy, and therefore repealed the amendment.¹⁷⁰

A structurally similar argument was made in Milieudefensie v. Royal Dutch Shell by the first instance court.¹⁷¹ While interpreting the normative content of the unwritten standard of care in civil law, the District Court turned to the UN Guiding Principles on Business and Human Rights (UNGP),¹⁷² which is a soft law compilation of principles addressed to states and companies. Although the UNGP do not impose binding obligations on corporations, the court nevertheless argued that ‘the responsibility of business enterprises to respect human rights, as formulated in the UNGP, is a global standard of expected conduct for all business enterprises’.¹⁷³ On these premises, the District Court ordered Shell to increase its mitigation efforts in line with its obligations under the UNGP.

These examples also suggest that the dividing line between hard law and soft law obligations often becomes blurred in future generations litigation. Courts appear to turn non-binding standards into judicially enforceable benchmarks to carve out certain policy choices from decision makers’ lawful room for manoeuvre. The soft law standards reflect a political consensus, negotiated irrespective of the particular lawsuit, on the measures that the courts deem necessary to protect posterity's long-term interests. Similarly, the scientific opinion of competent institutions with recognized prestige and expertise lends persuasive force to judicial findings that limit sovereign choices.

6. Conclusions on Transforming the Rule of Law: Trends and Implications

This snapshot of the frontlines of future generations litigation has shown how legal claims keep challenging the traditional content of states’ rule of law obligations across national, and also some international, jurisdictions. Courts are increasingly willing to interpret and apply traditional rule of law guarantees in a ‘revolutionary’ way: by extending their temporal scope to include both the concerns of future individuals as well as the future needs and rights of present-day subjects. Firstly, many jurisdictions now afford human rights safeguards against future environmental and climate hazards; and some even recognize unborn generations as rights holders. Secondly, national courts have also set various quality of law requirements for national climate laws to establish ambitious mitigation commitments. Thirdly, several jurisdictions have put constraints on the arbitrary exercise of governmental powers that threaten the viability of long-term natural assets, either by declaring such laws invalid or by compelling present decision makers to establish protective measures. Fourthly, while most lawsuits involving claims of age-based discrimination against minors are still pending, some courts have already shown sympathy for the discriminatory impact of adverse climate change on future generations. Finally, access to justice is increasingly granted in intergenerational lawsuits through expanding rules on justiciability and standing.

Courts concretize the meaning of legal standards through heterogeneous strategies, which are closely tailored to the specificities of national laws. Different modalities of rights-based approaches (including creating new rights holders), duty-centred reasoning, and concepts borrowed from Indigenous legal cultures¹⁷⁴ all have their rightful place in the judicial ‘toolbox’, depending on the interpretative canons of the applicable legal culture. Such heterogeneity appears to be inevitable. The success of future generations lawsuits depends, at least in part, on whether plaintiffs manage to find the appropriate doctrine to expand the contours of state obligations that is most in line with domestic legal traditions.

In sum, courts appear to delineate the interests of future generations worthy of judicial protection through one of five legal avenues, all of which flow from the rule of law. Accordingly, these rule of law pillars mark the application of the intergenerational equity principle in judicial practice. In many scenarios it would be difficult for courts to select long-term interests that ought to be protected through substantive standards, given that such interests can be vague and subjective, and thus contestable. In similar delicate situations in the past, courts have turned to procedural requirements in their environmental case law.¹⁷⁵ For the same reason, using the safeguards stemming from the rule of law are perhaps the most viable judicial tool to operationalize intergenerational equity.

On a higher level of abstraction, plaintiffs demand (with increasing success) that states respond to scientifically substantiated environmental risks and adopt ‘good laws’ with the purpose of diffusing ‘happiness and powers universally and equally’¹⁷⁶ – in our context, equally across generations. To that extent, successful future generations lawsuits insist on an ambitious justice concept as expressed within various theories of intergenerational justice.¹⁷⁷ At the minimum, unfolding judicial practice pushes present decision makers ‘to make wise choices for future generations’.¹⁷⁸

In the ‘laboratory’ of future generations litigation, courts translate the morally rooted requirement of passing good laws and making wise policies into binding obligations on states not to treat future individuals in an arbitrary way. Decisions and policy choices made in the present that are ‘capricious’ and unjustifiable in the light of scientific knowledge and soft law goals are repeatedly struck down by courts. States are no longer free to prioritize ‘at will’ certain short-term gains over long-term risks by wielding ‘uncontrolled power’ (to use colloquial synonyms of ‘arbitrary’) over ‘colonized’¹⁷⁹ future generations. Even though states do retain discretion in balancing competing interests, their actions are becoming increasingly scrutinized to ‘arriv[e] at a reasonable balance’¹⁸⁰ between present-day interests and longer-term impacts.

Judicially prohibiting arbitrary disregard for the interests of future generations may not be as revolutionary an idea as it may sound at first. It is in line with the changing contours of sovereignty, where states need to take into account ‘other-regarding considerations’ in designing their policies not only towards ‘foreign stakeholders’,¹⁸¹ but arguably also towards future stakeholders. Positing binding guarantees against arbitrariness towards future generations also resonates well with the idea that state sovereignty has inherent limits under international law and prohibits unreasonable exercise of sovereignty to the detriment of future people.¹⁸²

The implications of future generations lawsuits are of constitutional proportions; they call for transforming our conceptions of the meaning of the rule of law¹⁸³ and, through that, they might recalibrate some of the basic tenets of the current system of environmental and climate governance. More specifically, a transformed understanding of basic rule of law obligations, if spread across jurisdictions and maintained to a sufficient degree to solidify,¹⁸⁴ could assist in holding states liable for inflicting harm over longer timescales. By fostering a new, future-focused understanding of the rule of law, courts could level the playing field for later generations and emancipate them from the ‘systematic bias’¹⁸⁵ of current short-termist decision making.