Climate change presents one of the most disruptive challenges for contemporary legal systems. One aspect of climate change as a legal problem that is especially disruptive concerns the determination and extent of the duties of governments to address its causes and consequences. In this post, I analyze landmark climate litigation cases through a comparative lens, exploring how civil, common, and European legal traditions interpret governmental obligations in addressing climate change. I argue that the disruptive nature of climate change litigation compels courts across traditions to depart from conventional frameworks and develop novel forms of legal reasoning. That is already happening, albeit slowly, in many places.
Translating International Commitments into Domestic Obligations
At the international level, the legal obligations of states under the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement appear relatively uncontroversial. States have committed to stabilizing greenhouse gas (GHG) concentrations and limiting global warming to well below 2°C, with a required limit of 1.5°C, below pre-industrial levels, as per the International Court of Justice’s Advisory Opinion of July 2025. However, translating these broad commitments into justiciable duties at the domestic level has proven to be legally complex and politically fraught. Scholars such as Spier and Heri argue that the obligations imposed by the global climate change regime, combined with human rights law and principles of extracontractual liability, constitute a form of “global obligation.” Yet, though domestic courts in several states have invoked these international obligations to press governments for more ambitious action, the extent to which such a framework can be directly enforced remains uncertain.
Legal Traditions at the Crossroads of Climate Litigation
Civil law, with its roots in Roman law and codifications like the Napoleonic and German Civil Codes, is systematic and text-driven, relying on written statutes and deductive reasoning rather than judicial law-making. Common law, born in medieval England, grows case by case through precedent and analogical reasoning, its flexibility allowing it to evolve with social change. The European legal tradition, a post-war hybrid, blends the shared heritage of Roman law with human rights and European integration, operating in a multilingual, multilevel system defined by constitutional pluralism and judicial dialogue across borders. While historically distinct, these traditions increasingly interact in climate litigation, borrowing from each other’s methods to craft innovative responses to a common crisis.
Urgenda v. Netherlands: A Dynamic Civil Law Approach
Urgenda Foundation v. State of the Netherlands illustrates how civil law courts may blend domestic and international legal norms to craft enforceable climate duties. Because the Netherlands follows a monist approach, giving the European Convention on Human Rights (ECHR) the same legal status as domestic law, its courts can directly apply international human rights obligations. In practice, however, they often invoke the ECHR only through the “reflex effect,” using it to interpret the domestic law provisions. In Urgenda, the Dutch district court (Rechtbank Den Haag) relied on tort law provisions (specifically Article 6:162 of the Dutch Civil Code) to establish a duty of care, using Articles 2 (right to life) and 8 (right to respect for private and family life) of the ECHR in this reflexive way, not as direct legal bases but as interpretive tools. On appeal, the Court of Appeal (Gerechtshof Den Haag), and ultimately the Supreme Court (Hoge Raad), departed from this traditional approach and directly applied Articles 2 and 8 ECHR, acknowledging a positive duty to protect life and private life against the threats posed by climate change. The Dutch Supreme Court justified its ruling with reference to the “no harm” principle in international law. Ultimately, the court ordered a 25% reduction in Dutch GHG emissions by 2020 (para 8.3.5).
Urgenda demonstrates that, while the Dutch legal system is rooted in the civil law tradition and follows a monist approach to international law, its courts can reason in ways that echo common law methods. In this case, the judges went beyond a strict deductive application of codified norms, building their argument through cross-references to European Court of Human Rights (ECtHR) case law and climate science. This incremental, precedent-sensitive style, more typical of common law, allowed the court to apply Articles 2 and 8 ECHR directly to the realities of climate change. The court thus blended civil, European, and common law reasoning to deliver substantive justice in the climate context.
Canadian Climate Litigation: Cautious Common Law Interpretation
Canadian climate litigation cases, such as Environnement Jeunesse c Procureur général du Canada, La Rose v Canada and Mathur v His Majesty the King in Right of Ontario, reflect a more cautious approach that is rooted in common law tradition. In all three cases, plaintiffs attempted to invoke the Canadian Charter of Rights and Freedoms (Charter), particularly Sections 7 and 15, to establish positive governmental duties to adopt and implement a climate plan that reduces GHG emissions. The court’s response was more restrained and conservative than that seen in Urgenda, reflecting the common law traditions of individualism and liberalism.
As Parker has argued, a key issue in Canadian climate litigation is whether courts are willing to invoke the Canadian Charter of Rights and Freedoms to impose positive duties on governments to act on climate. In ENJEU, the Quebec Court of Appeal held that, absent a specific statutory duty, governmental inaction is not amenable to constitutional review (para. 25); it found the claims non-justiciable (paras. 39-42) and did not reach the Charter merits. Similarly, in La Rose, the Federal Court seemed willing to entertain the notion that positive obligations could emerge from Section 7 (para. 67), but ultimately struck the claim, while the Federal Court of Appeal left the possibility open for future development (para. 98). In Mathur, Justice Vermette of the Ontario Superior Court of Justice acknowledged the existential nature of climate change and its potential to justify novel legal duties (para. 138). However, because the applicants did not frame their case as a positive-obligations claim, she noted that recognizing such duties would entail a new Section 7 framework, a step she did not consider necessary in this case (paras. 139-142).
As the above examples show, despite Canada’s “living tree” doctrine which allows constitutional interpretation to evolve, courts have largely refused to extend this flexibility to climate rights, preferring to defer such determinations to the legislature. This reflects a conservative judicial posture in the face of novel and disruptive legal challenges, consistent with the common law’s incremental, case-by-case method. Canadian climate decisions fit in this pattern, although outcomes across common-law jurisdictions vary.
Neubauer v. Germany: Systematic but Restrained Constitutionalism
Neubauer v. Germany, illustrates a civil law court’s strict and systematic application of constitutional norms in the face of climate change. In Neubauer, the German Federal Constitutional Court (BVerfG) recognized that Article 2(2) of the Constitution, which protects life and bodily integrity, encompasses a governmental duty to engage in both mitigation and adaptation efforts (para. 150). Importantly, the court extended this duty to international climate obligations, thereby acknowledging the global nature of the climate crisis (para. 149). The court applied a stringent legal test, assessing the suitability and adequacy of existing legislation (e.g., Germany’s Federal Climate Action Act, or KSG), and concluded that the legislation was not manifestly unsuitable or entirely inadequate to achieve the constitutionally required protection of life and health against the risks posed by climate change (para. 155 ff.).
While the BVerfG acknowledged the seriousness of the climate threat and the state’s obligation to act, it did not find a constitutional violation (para. 151). This reflects a civil law approach grounded in codification and legal rationalism. The court remained cautious and doctrinal and was unwilling to extend legal interpretation beyond its established boundaries. Unlike in Urgenda, where the court took a dynamic approach, the German court remained cautious and doctrinally rigid. However, Neubauer did make important contributions by embedding climate change within constitutional protection frameworks and confirming the role of international obligations in domestic climate governance.
KlimaSeniorinnen v. Switzerland: Bridging Traditions at the ECtHR
Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, decided by the Grand Chamber of the European Court of Human Rights (ECtHR) in April 2024, illustrates a unique synthesis of legal traditions within the European legal order. This was the first substantive ruling on climate change by the ECtHR and it represents a milestone in climate litigation. The court held that Switzerland had failed to fulfill its positive obligations under Article 8 ECHR, which protects the right to private and family life (para. 562). The court interpreted Article 8 as encompassing the state’s duty to protect individuals from the adverse effects of climate change, including health, well-being, and quality of life (para. 519).
The court’s reasoning was comprehensive and methodical, reflecting civil law principles of structured legal analysis. However, it also embraced common law-style adaptability by developing a novel five-part test to assess whether states have complied with their ECHR obligations in climate cases (para. 550). The test examines the existence of general reduction targets, intermediate pathways, actual implementation, evidence-based updates, and timely enforcement (para 550). Importantly, the ECtHR emphasized that states cannot invoke domestic constitutional procedures, such as referenda or legislative delays, as excuses for failing to comply with human rights obligations (para. 561). Klimaseniorinnen reflects the ECtHR’s role as a transnational legal actor capable of harmonizing divergent legal traditions and advancing environmental human rights protections. By drawing from case law across Europe—including Urgenda (paras. 260-261), Neubauer (paras 254-257), and others—the court demonstrated a comparative and integrative approach to climate adjudication.
The ECtHR’s recognition of climate change as a human rights crisis and its willingness to evolve legal standards reflect both civil and common law features. The court’s methodical and comprehensive examination of the state’s obligations and its use of structured legal tests resonate with the civil law tradition’s emphasis on rationality, codification, and systematic reasoning. However, the ECtHR’s interpretation of existing human rights to include environmental protections illustrates a flexible and adaptive judicial approach, aligning more closely with common law principles. The ECtHR demonstrates a willingness to evolve the interpretation of the ECHR in response to contemporary challenges, akin to the dynamic and organic nature of common law systems. By recognizing positive obligations and setting specific criteria for states to fulfill their duties, the ECtHR exhibits a creative and flexible judicial approach–one that contrasts with the rigid application of pre-defined legal standards typical of the civil law tradition.
Conclusion: Emerging Judicial Convergence
Taken together, these case studies show that, while climate change presents a common legal challenge, the manner in which courts respond is shaped by their underlying legal traditions. Dutch courts and the ECtHR have used adaptive human-rights reasoning, and, in the Netherlands, domestic tort, in tandem with climate science, to craft enforceable duties. Germany’s Federal Constitutional Court has grounded climate duties in fundamental rights and required tighter post-2030 planning, but done so through a structured constitutional analysis. Canadian courts have been more cautious about constitutionalizing broad positive obligations, reflecting an institutional hesitancy that departs from the common law’s reputed flexibility and adaptivity. Mathur nonetheless signals some openness to revisiting the doctrinal frame.
Although legal traditions continue to shape judicial approaches, they are not deterministic. Courts possess the institutional capacity to reinterpret existing legal norms and develop new doctrines responsive to the unique challenges posed by climate change. The cases studied indicate that both civil and common law systems can evolve to meet these challenges—either through doctrinal innovation, as in Urgenda and KlimaSeniorinnen, or through cautious constitutional interpretation, as in Neubauer and Mathur. The blending of legal traditions in some cases suggests the emergence of a transnational judicial dialogue on climate duties; one that could gradually consolidate around shared principles of environmental justice and intergenerational equity.
Overall, it is clear that the judiciary, far from being a passive actor, plays a critical role in navigating the legal disruption posed by climate change. By examining how courts in different legal systems interpret the duties of government, we can get valuable insights into the evolving nature of climate law and the potential for transsystemic legal reasoning to address global challenges.