‘Common But Differentiated Responsibilities’ in the National Courts: Lessons from Urgenda v. The Netherlands

Abstract

The landmark 2015 decision by the Hague District Court in Urgenda v. The Netherlands represents the first time a national court has expressly used the international environmental law (IEL) principle of common but differentiated responsibilities and capabilities (CBDRs) of the climate regime as a complementary tool to interpret the scope of a state’s climate obligations under domestic law. This article highlights that despite the marked engagement of national courts with IEL in recent decades (including engaging with principles such as sustainable development, polluter pays, intergenerational equity, and precaution), until this decision CBDRs had remained outside the purview of environmental law jurisprudence at the national level. The article examines how the Hague Court used CBDRs to help address two common barriers to climate liability: causation and the ‘political question’ doctrine. The article argues that the Court was able to find normative content in a core element of the climate-related CBDRs: the ‘leadership’ role of developed countries in climate action. This core element has remained remarkably consensual throughout the contested history of CBDRs in the climate regime – a history that has gained a new chapter with the signature of the Paris Agreement in December 2015. The article concludes that Urgenda v. The Netherlands may serve as a starting point for a more productive and extensive use of CBDRs in climate litigation, provided litigants make more explicit use of the persuasive authority of the principle.

1. INTRODUCTION

[T]he state should not hide behind the argument that the solution to the global climate problem does not depend solely on Dutch efforts. Any reduction of emissions contributes to the prevention of dangerous climate change and as a developed country the Netherlands should take the lead in this. ¹

On 24 June 2015, the Hague District Court (the Court) gave its decision in the case of Urgenda v. Government of the Netherlands (Ministry of Infrastructure and the Environment) (Urgenda). ² The Court’s decision established that, in order to meet its standard duty of care towards the plaintiffs (the Urgenda Foundation, ³ representing current and future generations of Dutch citizens threatened by the risks of climate change), the Dutch government was ordered to ‘limit the joint volume of Dutch annual greenhouse gas [GHG] emissions, or have them limited, so that this volume will have reduced by at least 25%–40% at the end of 2020 compared to the level of year 1990’. ⁴

Urgenda’s target and timeline are based on the 2007 projections by the Intergovernmental Panel on Climate Change (IPCC) of required mitigation action by the group of Annex I developed countries that ratified the 1992 United Nations Framework Convention on Climate Change (UNFCCC). ⁵ State parties to the UNFCCC have agreed to negotiate the allocation of responsibilities and costs for global climate action according to the principle of common but differentiated responsibilities (CBDRs) and capabilities. Developed countries have agreed to ‘take the lead’ in climate mitigation in order to limit temperature increase to 2 degrees Celsius (^oC) above pre-industrial levels (and well below 2^oC, with efforts to keep it under a 1.5^oC increase since the December 2015 Paris Agreement) ⁶ by taking urgent and more stringent action than that required of developing countries. ⁷

The Urgenda decision has already received a fair amount of scholarly attention, despite it being only one year old. ⁸ The judgment has been lauded as historic for representing the first time a court has issued a mandatory order for a government to adopt nationwide mitigation targets, outside a statutory mandate; ⁹ the first time a court has successfully used tort law (state negligence towards a required standard duty of care) in a climate-related action; ¹⁰ and the first time a court has determined a mandatory minimum emissions-reduction target for a developed state. ¹¹ Scholars have critically analyzed the Court’s position and reasoning on issues such as standing, ¹² the ‘political question’ doctrine, ¹³ its innovative use of the tort of negligence, ¹⁴ and its promising example for citizen suits in climate litigation. ¹⁵

The Urgenda decision introduced another ground-breaking development in environmental liability, which so far has received no scholarly attention: the judgment marks the first occasion on which a national court expressly used the international environmental law (IEL) principle of CBDRs as a complementary tool to interpret the scope of a state’s climate obligations under domestic law. This article argues that the Court was able to find normative content in a core element of the climate-related CBDRs: that is, the ‘leadership’ role of developed countries in climate action. This core element has remained remarkably consensual throughout the contested history of CBDRs in the climate regime, history which gained a new chapter with the signature of the Paris Agreement in December 2015.

The remainder of the article is structured as follows. Section 2 sets the context and highlights the fact that, despite the marked engagement of national courts with IEL in recent decades (including engaging with principles such as sustainable development, polluter pays, intergenerational equity, and precaution), until this decision CBDRs had remained outside the purview of environmental law jurisprudence at the national level. Section 3 clarifies that the case is not one of direct application of CBDRs by a national court, but rather a case where the Court used the CBDRs principle as an interpretive aid to help in determining the scope of national obligations. Section 4 describes the Court’s use of CBDRs in the landmark decision to help address two common barriers to climate liability: causation, and the ‘political question’ doctrine. Section 5 briefly revisits the contested and dynamic evolution of CBDRs in the climate regime, arguing that the concept of ‘leadership’ of developed countries in global climate action has remained constant, and it is this core concept that informed the Court’s decision in Urgenda.

2. CBDRs AS A LATE ENTRANT IN CLIMATE LITIGATION IN NATIONAL COURTS

Much has been written about the potential role of national courts in promoting the implementation of international treaties and in contributing to the evolution of international norms. ¹⁶ The literature recognizes that, in practice, the direct engagement of national courts with international law has traditionally been less forthcoming than its promised potential for at least three interrelated reasons:

• ∙ the responsibility for creating, implementing and enforcing international law rests primarily with the legislative and executive branches; ¹⁷

• ∙ generally, national courts tend to favour the application and interpretation of domestic law, including law that implements international treaties; ¹⁸

• ∙ for a long time, many national courts used avoidance techniques to evade interfering with what they consider to be international political questions (rather than legal disputes), which are better addressed through interstate negotiations. ¹⁹

Since the 1990s, however, an increasing number of national courts in an expanding number of jurisdictions have engaged with international law, ²⁰ either by interpreting national law in conformity with international norms or, ²¹ to a lesser extent, by directly applying international law in domestic legal cases. ²² The significance of this trend is reflected in the number of prominent academic initiatives to identify and analyze leading cases that involve the engagement of national courts with international law, ²³ and to investigate the patterns of this evolving engagement. ²⁴ However, this trend may vary in different areas of international law. While it seems clear that national courts increasingly engage with international human rights law, ²⁵ there is still some debate as to the extent to which this engagement with IEL follows a similar upward trend.

A comparative analysis, in 2002, of whether and how national courts in 12 jurisdictions had engaged with IEL, commissioned by the American Society of International Law (ASIL), concluded that at least until the late 1990s national courts had directly applied IEL in only a few isolated cases. ²⁶ The use by national courts of IEL as an interpretive tool of national legal instruments had also been limited, especially when compared with other international law areas such as human rights. In contrast, the fourth volume of the 2005 edition of the International Environmental Law Reports, edited by Alice Palmer and Cairo Robb, identified 50 leading decisions of national courts from 26 different jurisdictions, all of which broadly engaged with IEL. ²⁷ Most of these decisions were delivered during the 1990s and early 2000s.

Palmer and Robb observe that the national court decisions could be characterized ‘as having made a positive contribution to the development of international [environmental] law’, although they do recognize that IEL was often only one of the factors considered by national courts in their legal reasoning. ²⁸ Carl Bruch also argues that the 1990s and 2000s marked a ‘dramatic increase in the number of cases [where national courts] interpret and apply [IEL]’, noting that national courts currently use IEL ‘for a wide range of purposes and in various contexts’. ²⁹

Although the receptiveness of national courts with IEL would still benefit from further analysis, the studies already show that in a considerable number of instances national courts have considered that key principles of IEL (such as the precautionary principle, the principle of sustainable development, the polluter pays principle and the principle of intergenerational equity) had a material role to play in the interpretation of national norms related to environmental protection or environmental disputes. ³⁰ From the perspective of the evolution of IEL this engagement is relevant because national courts contribute to clarifying (or sometimes to complicating) what are often still vague concepts, while also helping to illuminate their potential evolution into customary norms of general application. National court decisions engaging with IEL principles can also help to establish a more significant role for these principles in the protection of environmental resources and in the resolution of environmental law disputes in other national legal orders. ³¹

The studies show that despite national courts’ noteworthy engagement with most of the main principles of IEL, they have yet to recognize certain principles as having a material role to play in the protection of environmental resources or the resolution of environmental disputes at the national level. One such overlooked principle is that of CBDRs. The ASIL, Palmer & Robb, and Bruch studies show no record of a national court interpreting national legal instruments in conformity with CBDRs, or using CBDRs to help in determining the scope of domestic obligations, or employing CBDRs as part of their reasoning when adjudicating environmental law disputes. The Urgenda decision, therefore, has broken new ground by expanding the number of IEL principles on which national courts have relied as persuasive authority. The next section describes how, prompted by the plaintiffs, the Hague Court expressly engaged with CBDRs.

3. CBDRs AS A TOOL TO INTERPRET NATIONAL LAW OBLIGATIONS

On 20 November 2013, the Urgenda Foundation (the plaintiffs) sued the Government of the Netherlands before the District Court of the Hague, arguing that the state had breached its duty of care towards Dutch citizens by not pursuing a minimum GHG reduction target of 25% to 40% from 1990 levels by the year 2020. ³² The Urgenda summons is possibly the first before a national court to clearly articulate the CBDRs principle, among other international law principles, as part of the applicable law in a domestic climate lawsuit. The plaintiffs argued that the state could be held liable for the volume of Dutch GHG emissions based on both national legal principles and provisions and on general principles of international law and European Union (EU) law. ³³

The plaintiffs emphasized the monist approach to international law in the Netherlands, where international norms that are ‘binding on all persons by virtue of their contents’ are directly applicable in the national legal system. ³⁴ By failing to take adequate and timely mitigation measures, the state should be declared liable for breaching the ‘no harm’ principle of IEL, and Articles 2 (right to life) and 8 (right to private and family life) of the European Convention on Human Rights (ECHR). ³⁵ The plaintiffs based their claim on national law as well, arguing that the state breached the Dutch standard duty of care to prevent ‘significant’ harm to its citizens, thereby incurring liability in tort for negligence. ³⁶ The plaintiffs further argued that Dutch courts may rely on non-binding treaty provisions as authoritative sources of interpretation to support findings of breaches of both international and national law. ³⁷

CBDRs were explicitly included in the summons, along with other relevant principles and commitments of the UNFCCC, as the plaintiffs’ ‘proceedings against the State, in essence, build upon [the authoritative force of those principles and commitments]’. ³⁸ The plaintiffs argued that state parties to the UNFCCC, including the Netherlands, had agreed ‘that developed and developing countries have “common but differentiated responsibilities in combating climate change”’ ³⁹ based on their different historical and current levels of emissions and capabilities. At several points the summons expressly articulated that developed countries (including the Netherlands) had agreed to ‘take the lead’ in combating climate change and its negative effects. ⁴⁰ More specifically, the plaintiffs argued that the Netherlands and other parties of the UNFCCC had agreed in the form of various decisions ‘that rich countries with a long history of [GHG] emissions that have caused the problem, and those with high per capita emissions, have an obligation to take the lead and be the first to realise their necessary emissions by 2020’. ⁴¹

The Court’s legal reasoning in Urgenda begins with the establishment of the substantive issues on which the plaintiffs and the Dutch government (the defendant) concur. Parties agree that anthropogenic GHG emissions cause climate change, that ‘a highly hazardous situation for man and the environment [globally and locally] will occur with a temperature rise of over 2^oC compared to pre-industrial levels’, and that significant mitigation action is needed to avoid dangerous climate change. ⁴² The core dispute, according to the Court, revolves around the level (or stringency) and the pace (or urgency) of emissions reductions that the Dutch state is legally required to adopt. The plaintiffs argued that in order to meet its duty of care the state must reduce its GHG emissions by at least 25% to 40% by the end of 2020, compared with 1990 levels. The state argued that it had the discretionary power to decide on the stringency and urgency of emissions cuts.

In deciding this core dispute, the Court expressly declined to derive a legal obligation directly from the principles and provisions of the UNFCCC or from EU climate law. Urgenda is not a case of direct application of IEL or EU law by a national court. However, the Court decided that the global nature of climate change, and the collective nature of the ‘shared risk management’ needed to address this hazard, required the consideration of the objectives and principles laid down in the UNFCCC and EU climate law. ⁴³ According to the Court, the objectives and principles found in international law and policy were relevant in order to determine the ‘scope of the State’s duty of care (based on national law) and the discretionary power it is entitled to’. ⁴⁴ A large part of the Urgenda ruling offers an account of relevant international and EU ⁴⁵ climate law and policy. ⁴⁶

The Court reproduced the relevant provisions of the UNFCCC and its Kyoto Protocol, ⁴⁷ as well as various decisions by the Conference of Parties (COP) to the UNFCCC. The Court expressly referred to CBDRs when it highlighted that the UNFCCC Preamble calls for the ‘widest possible cooperation by all countries … in accordance with their common but differentiated responsibilities and respective capabilities and their social and economic conditions’. ⁴⁸ The judgment also reproduced Article 3 UNFCCC, which includes the principle of CBDRs in an operational provision. ⁴⁹

The Court expressly included differentiated responsibilities among a list of other relevant principles such as ‘protection of the climate system, for the benefit of current and future generations, based on fairness, “the precautionary principle”, and “the sustainability principle”’. ⁵⁰ The Court included both the principle of intergenerational equity (the protection of the interests of present and future generations) and the principle of intragenerational equity, which normally correlates with CBDRs, in its broad definition of the ‘fairness principle’. For the purposes of this article, I concentrate on how the Court articulated the intragenerational aspect of the fairness principle.

The Court explicitly established that ‘the principle of fairness … expresses that industrialized countries have to take the lead in combating climate change and its negative impacts’. ⁵¹ It went on to analyze what this leadership could represent in practice. The Court decided that since the disagreement involves difficult climate-related substantive issues which are outside the Court’s expertise, it should base its legal assessment of the State’s obligations on the findings of the IPCC, international climate policy agreements, and Dutch climate policy documents which both the plaintiffs and defendant recognize as correct. More specifically, the Court described how, under the terms of the UNFCCC and its Kyoto Protocol and subsequent COP decisions, developed countries have agreed to take the lead by committing to more stringent emissions reduction targets, and also to provide financial resources, technology transfer and capacity building to enable mitigation in non-Annex I (developing) countries.

Differentiation also appears in the decision when the Court analyzed the specific Dutch reduction targets. The Court referred to the IPCC Fourth Assessment Report, ⁵² in which the scientific body concluded that the total emissions of Annex I countries will have to be ‘25 to 40% lower in 2020 compared to 1990 – with due regard for a fair distribution’, while non-Annex I countries would also have to reduce emissions substantially below business as usual, in order to keep safe concentration levels of GHG. ⁵³ The Court stated that the Ad Hoc Working Group of Annex I countries expressly acknowledged in the 2010 Cancun Agreements ⁵⁴ that they would have to limit their emissions by the levels specified by the IPCC in order to reach the stabilization goal established by the UNFCCC. ⁵⁵

In sum, the Court partially relied on CBDRs, as part of the body of international climate law and policy, to find that the projected Dutch climate policy for 2020 was insufficient to meet its standard duty of care, in light of its commitment to take the lead in climate action together with other developed countries. The Court also engaged with CBDRs when dealing with two common barriers to climate liability at the national level, which I discuss next.

4. CBDRs AND TWO COMMON BARRIERS TO CLIMATE LIABILITY

As climate lawsuits before national courts in various jurisdictions increased in number and sophistication in the mid-2000s, ⁵⁶ a range of significant barriers to climate liability came to the forefront of legal discussion. ⁵⁷ Causation and the ‘political question’ doctrine are two of the most discussed barriers in the climate litigation literature. The Court explicitly engaged with the CBDRs principle in dealing with these questions in Urgenda. To be clear, the Court did not rely on CBDRs as the sole or even the primary foundation for its decisions on causation and the ‘political question’ doctrine; yet, CBDRs did feature as a significant complementary interpretive tool.

4.1. CBDRs and the Challenge of Causation

Many legal doctrines require proof of causation, which broadly speaking means ‘the link between an actor’s behavior and subsequent harm to another’, in order to establish liability. ⁵⁸ Proving causation may represent the most significant challenge for climate change liability because of the multi-scale nature of the problem, with its large number of concurrent tortfeasors. ⁵⁹ Even excluding the problem of deferred impacts of past emissions, a multitude of states and private actors currently emit GHGs and are collectively responsible for climate change. ⁶⁰ Some of these actors, including large emitters such as the United States (US) and China, and fossil fuel companies like Chevron, Exxon Mobil or BP, may be individually responsible for materially significant volumes of emissions. With a population of around 16 million and a relatively small territory, the Netherlands is definitely not among the largest sources of GHG emissions in absolute terms. The emissions of actors such as the Netherlands, however, become relevant when added to the emissions of others.

The existence of multiple tortfeasors, with relatively insignificant emissions when taken individually, represents a challenge to traditional liability conceptions of causation. In Urgenda, the Court followed recent tort law developments to address the question of causation, but it also innovated by invoking the concept of developed countries’ leadership in climate action, based on CBDRs, as complementary persuasive authority to dismiss traditional defences against causal liability in climate litigation.

In determining liability, courts usually assess specific (or proximate) causation, which refers to the extent to which the plaintiff’s particular harm or risk results from the conduct of the specific defendant or group of defendants. The general test in tort law for proximate causation is the ‘but for’ test, ‘which requires the plaintiff to show that the injury would not have occurred but for the negligence of the defendant’. ⁶¹ Courts in many jurisdictions have declined to apply the ‘but for’ test in cases of cumulative environmental harm, since it is practically impossible for the plaintiff to prove that the injury would not have occurred but for the conduct of the particular defendant. Establishing specific causation is especially difficult in climate change cases because of the multitude of sources of GHG emissions responsible for climate change across time and across space. ⁶²

In several jurisdictions courts use the test of substantiality, or material contribution, to establish proximate causation in environmental cases. ⁶³ This test evaluates whether the defendant’s conduct ‘materially contributed’, or substantially contributed, to the injury. ⁶⁴ In the emblematic US Supreme Court decision in Massachusetts v. Environmental Protection Agency (EPA), the defendant argued that the level of unregulated GHG emissions from motor vehicles contributed ‘insignificantly’ to the plaintiffs’ harm, and should therefore generate no liability. ⁶⁵ The majority of the US Supreme Court found that the emissions ‘made a meaningful contribution to [GHG] concentrations’, and hence to global warming. ⁶⁶

In Massachusetts v. EPA, the US Supreme Court also addressed the defendant’s argument that the relief sought by the petitioners would not be an efficient remedy for the injury or risk of injury from climate change. The defendant US EPA argued that growing emissions from ‘developing nations, particularly China and India, are likely to offset any marginal domestic decrease’. ⁶⁷ The Supreme Court found for the petitioners, affirming that increases in emissions abroad did not diminish the fact that ‘[a] reduction in domestic emissions would slow the pace of global emissions increases, no matter what happens elsewhere’. ⁶⁸

In Urgenda, the Hague Court had to confront similar legal questions related to (i) the multi-scale nature of emissions and the fact that a state’s unilateral regulatory action cannot realistically represent an effective remedy; and (ii) the fact that the Dutch absolute GHG emissions are insubstantial compared with certain other sources of emissions. Many courts will need to address similarly difficult legal questions in future climate change cases. Although the Hague Court relied on the concept of material contribution, which had already been employed by the US Supreme Court, it innovated by invoking CBDRs to address the question of international cooperation and the concurrent contributions of other countries to climate change.

The Dutch state argued that adopting the 25% to 40% emissions reduction by 2020, as requested by the plaintiffs, would still result in a ‘very minor, if not negligible, reduction in [GHG] emissions’, since this would represent only 0.04% to 0.09% of the global total. ⁶⁹ The state emphasized that, according to science, the level of emissions reduction necessary to avoid dangerous climate change depended mainly on the actions of other countries, especially those with high emissions levels. As the US Supreme Court did in Massachusetts v. EPA, the Hague Court rejected this defence and reasoned that, since it had been established that any level of anthropogenic GHG emissions contributes to hazardous climate change, the Netherlands still had the responsibility to take measures, no matter how small the size of its emissions compared with others, in order to fulfil domestic obligations to exercise care. ⁷⁰

To support its finding of liability, the Court also relied on the global and cooperative nature of the solution to climate change, expressly addressing the question of differentiation in helping to define the scope of the Dutch obligations. The Court found that all countries, including the Netherlands, will need to ‘implement the reduction measures to the fullest extent’. ⁷¹ The Court added: ‘[H]ere too, the court takes into account that in view of a fair distribution the Netherlands, like other developed countries, has taken the lead in adopting mitigation measures and has therefore committed to a more than proportionate contribution to reduction’. ⁷² It went on to say that ‘it is beyond dispute that the Dutch per capita emissions are one of the highest in the world’, which is another argument related to global discussions on CBDRs. ⁷³

Hence, the Court partially relied on international law and policies to conclude that, as a developed country and party to the UNFCCC, the Netherlands had endorsed the specific IPCC targets of 25% to 40% below 1990 levels by 2020, independently of the actions of developing countries.

4.2. CBDRs and the ‘Political Question’ Barrier

Many climate change cases, especially in the US, have been declared ‘non-justiciable’ because of the wide discretion conferred on legislators and politicians in establishing national and foreign policies to address climate change – a problem which involves significant national and international political economy considerations. ⁷⁴ Even when a climate action is admitted as justiciable, defendants often argue that, on the merits, the question belongs to the realm of the executive or the legislative branches.

In the Urgenda case, the Dutch state advanced two lines of defence related to the ‘political question’ doctrine. Firstly, it argued that a judicial decision to mandate a more stringent climate policy would ‘interfere with the system of separation of powers and could damage the Netherland’s bargaining position in international climate negotiations’. ⁷⁵ Secondly, it argued that a judicial decision would be ‘contrary to the State’s discretionary power’ to define appropriate climate action. The Court partially relied on UNFCCC climate provisions and policies, including CBDRs, in addressing the second line of defence.

In relation to the first line of defence, the Court held that the separation of powers was not absolute under Dutch law. ⁷⁶ The Court established that the judiciary has the mandate to apply the law when asked to do so, even in complex legal questions involving political consequences. ⁷⁷ On the interference with global climate negotiations, the Court held that when a legal obligation is established by the courts, the state does not have the authority to disregard this obligation in the context of international negotiations. ⁷⁸ The Court conceded that the complex climate change problem justifies the widest possible discretionary policy space for the government to implement the obligation. According to the Court, this discretionary space, however, has limits set by the duty of care owed to Dutch citizens.

The Court invoked a key element of CBDRs – namely, the leadership of developed countries in combating global climate change – when discussing the second line of defence. In considering the scope of the discretionary power of the Dutch government in fulfilling its standard duty of care, ⁷⁹ the Court found that, although Article 21 of the Dutch Constitution gives the state, in principle, wide discretion to define appropriate national environmental policies, this discretionary power is not unlimited. ⁸⁰ The Court revisited the idea that the nature of the problem (a global phenomenon) and the required response (shared risk management of a global hazard) justifies taking into consideration the objectives and principles of the UNFCCC and EU climate law in deciding the discretionary limits. ⁸¹

The Court decided that the government cannot ignore climate science and global climate politics in fulfilling its obligation to adopt effective national climate policies to address the climate threat to Dutch citizens. It judged that the state cannot, for example, focus primarily on adaptation when establishing national policies, after IPCC studies (not disputed by the defendant) showed that adaptation will offer only limited protection if significant mitigation action is not urgently undertaken. ⁸² On this point, the Court decided that ‘from the viewpoint of efficient measures available the State has limited options: mitigation is vital for preventing dangerous climate change’. ⁸³ It then proceeded to the question of the state’s discretionary power to decide which levels of mitigation to adopt.

The Court concluded that the discretionary power of the government to decide national levels of mitigation was limited by the state’s required engagement in the international cooperative regime to address climate change. Under the UNFCCC, as an Annex I (developed) country, the Netherlands has agreed to take the lead in adopting mitigation measures ‘and has therefore committed to a more than proportional contribution to reduction, in the view of a fair distribution between industrialized and developing countries’. ⁸⁴ Based on IPCC calculations and UNFCCC policies for developed countries, the Court decided that the state should limit the joint volume of Dutch GHG emissions by at least 25% to 40% by the end of 2020, compared with the levels in the year 1990.

Urgenda marks the first occasion on which a national court has used CBDRs as an interpretive aid, in parallel with other IEL and EU law principles, in helping to establish the scope of a country’s environmental obligations at the national level. It must be acknowledged that the weight the Court accorded to CBDRs in the decision is unclear. Nevertheless, by expressly invoking the concept of differentiation as a general interpretive principle in helping to establish the scope of obligations, and as a complementary tool to reject the defence arguments, the Court indicated that CBDRs do have ‘legal gravitas’, ⁸⁵ or persuasive authority. The Court relied on one core element of CBDRs that has remained consensual throughout the contested history of this principle in the climate regime, which is what I examine next. ⁸⁶

5. ‘TAKING THE LEAD’ AS A CORE ELEMENT OF CBDRs

The Hague Court’s use of CBDRs in Urgenda has illuminated a core content of the climate-based CBDRs that has remained constant and consensual throughout the contested and dynamic history of this principle in the climate regime. Parties to the UNFCCC strongly disagree on the philosophical or ideological premises that justify differentiation, and on how exactly differentiation should be expressed in the provisions of the legal instruments of the climate regime. In this section I argue that, despite these disagreements, there has been a sustained consensus that developed countries will take the lead by shouldering a heavier burden (acting early and more significantly) in reducing emissions. ⁸⁷ This consensus was present in the otherwise disputed top-down model of the 1997 Kyoto Protocol, which established exclusive mitigation obligations for developed countries, and persists in the bottom-up and more nuanced differentiation model of the 2015 Paris Agreement.

The Court in Urgenda relied on this core consensual element of CBDRs to mandate the Netherlands, as a developed country, to take urgent and significant action to contribute to the collective solution of the global climate change problem.

5.1. Contestation and Discontinuities in the Climate CBDRs

The literature on CBDRs highlights the deeply contested nature of this principle in the climate regime. In contrast, differentiation in other multilateral environmental agreements (MEAs) has been significantly less controversial. Lavanya Rajamani explains this with reference to the marked differences between climate CBDRs and differentiation in other MEAs, both in terms of the extent of the differentiation and the very nature of the differential provisions. ⁸⁸ In the UNFCCC, the principle of CBDRs serves as the ‘anchor provision’ ⁸⁹ of the whole legal framework and appears in the Preamble as well as in several substantive and operational provisions. ⁹⁰ No other MEA adopts such a strong and articulated form of preferential treatment for developing countries.

Rajamani also argues that the UNFCCC and its Kyoto Protocol were the only two MEAs that differentiated between parties with respect to the central obligations of a regime. ⁹¹ Central obligations are designed to directly fulfil the object of the treaty. In the case of the climate regime, the primary objective, although not the only one, ⁹² is to stabilize GHG concentrations in the atmosphere ‘at a level that would prevent dangerous anthropogenic interference with the climate system’. ⁹³ Under the Kyoto Protocol, only developed countries were required to meet quantitative emissions reduction targets. ⁹⁴ No MEA other than the Kyoto Protocol has imposed exclusive obligations on developed countries relating to the core objective of the agreement.

Moreover, no other MEA expressly allows developing countries to meet the core objective of the agreement on a voluntary basis. In the Kyoto Protocol, developing countries (including emerging economies) were not simply given flexibility in the implementation of core obligations (in the form of, for example, deferred base years or assisted compliance). Instead, they were made completely exempt from binding obligations towards a central objective of the climate regime: to reduce anthropogenic GHG emissions, concentration of which provokes hazardous climate change. ⁹⁵

The CBDRs in the Kyoto Protocol have been a major object of contention among the parties to the climate change regime. ⁹⁶ The US has been especially vocal in rejecting the idea of differentiation as granting emerging economies exemptions from climate mitigation obligations. ⁹⁷ The US Congress arguably refused to ratify the Kyoto Protocol for that reason. ⁹⁸ Over time, other developed countries, too, became more forceful in calling for reconsideration of their exclusive mitigation obligations, especially after the emission levels of countries such as China, India and Brazil grew significantly. ⁹⁹

With the Kyoto Protocol largely considered a failure, parties have tried to find a new balance that could accommodate their conflicting views in a new model for differentiation. Until the 2009 UNFCCC COP in Copenhagen (Denmark), a new compromise seemed elusive, as parties could not agree on an allocation formula that reflected their preferences. ¹⁰⁰ Emerging economies rejected the idea of moving towards a more equal allocation of burdens if it did not reflect their development needs and developed countries’ greater historic responsibilities and capabilities to act on climate change. ¹⁰¹ Developed countries strongly rejected the idea of continuing to exempt developing countries, especially emerging economies with high emissions, from assuming their share of the burdens and costs of climate action. ¹⁰² The parties famously failed to reach agreement for a new legally binding instrument at Copenhagen, primarily as a result of the disputes over fairly differentiated burdens. ¹⁰³

With hindsight, Copenhagen can be said to have marked the end of the paradigm of a top-down, rigid, binary differentiation of CBDRs. Emerging economies came to accept the idea that they would not be totally exempt from mitigation action. ¹⁰⁴ The new paradigm first proposed in Copenhagen is a bottom-up, more horizontal system, in which each country defines its own intended nationally determined contributions (NDCs) according to national circumstances. ¹⁰⁵ This bottom-up approach was the model officially incorporated in the 2015 Paris Agreement. ¹⁰⁶

There is broad recognition that the Paris Agreement represents a ‘fundamental shift away from the categorical binary approach of the Kyoto Protocol toward more nuanced forms of differentiation’. ¹⁰⁷ To begin with, the common nature of climate responsibilities was strengthened, with all parties to the Agreement mandated to formulate, to communicate and to update their climate action pledges. The mitigation and adaptation commitments became non-binding on all parties, although developed countries have the normative expectation to maintain absolute emissions reduction targets, while developing countries are encouraged to move towards absolute emissions cuts in the future. ¹⁰⁸

There is a common system of reporting and review, with flexibility mechanisms which do not follow the developed versus developing divide, but rather take into account various national capacities and circumstances. ¹⁰⁹ The exemption of developing countries from mitigation action is of the past, as are the exclusive mandatory mitigation targets for developed countries. In fact, the principle of CBDRs gained a new addendum: ‘in the light of different national circumstances’. This expression allows parties to take into account criteria such as geographic size and natural resources endowments when proposing their NDCs.

If widespread participation in an MEA is a sign of support for its core elements, there is arguably a compelling international consensus on the core provisions of the Paris Agreement, including its new differentiation arrangement. During the ‘Opening for Signature’ ceremony of the Agreement, held at the United Nations (UN) Headquarters in New York (US) on 22 April 2016, 175 parties (174 states and the EU) signed the Agreement, and 15 states deposited instruments of ratification. ¹¹⁰ It was the largest collective signing of an international agreement on a single day in the history of treaty making. ¹¹¹

This popular signing ceremony contrasts sharply with 16 March 1998, the date on which the UN held an equivalent ceremony to open the period for the official signing of the Kyoto Protocol. On that occasion, only six countries signed the agreement: with one exception (Switzerland), no developed country signed the Protocol during the ceremony; nor did China, India, or other emerging economies. Seven long years would elapse before the Kyoto Protocol entered into force, showing a high level of dispute over the differentiation model it represented.

Time will tell whether the strong disputes over the early manifestation of CBDRs in the climate regime will reappear during the negotiations on how to operationalize the Paris Agreement provisions, or during the implementation of the legal instrument. Yet, the history of the climate CBDRs also includes areas of consensus and continuity.

5.2. Continuity in the Climate CBDRs: Leadership by Developed Countries

Copenhagen arguably marked the beginning of a paradigm shift in the manifestation of CBDRs in the climate regime, and yet this narrative tells only part of the history. The focus on the end of the stark differentiation model that exempted developing countries from any obligation, and imposed mitigation targets exclusively on developed countries, hides some important continuities in the climate CBDRs – from the 1992 UNFCCC, through the 1997 Kyoto Protocol and the 2009 Copenhagen COP, to the 2015 Paris Agreement.

The continuity that is relevant to the argument of this article is the persistent consensus that developed countries will ‘take the lead’ in climate action, although the exact meaning of this leadership has been kept vague. The paradigm shift is perhaps less that the Paris Agreement marked the end of a binary differentiation between developed and developing countries in the climate regime, and more that the concept of a ‘leadership role’ for developed countries has ceased to be equated with exclusive obligations towards the core objective of climate mitigation.

The explicit mention of a leadership role arising from differentiated responsibilities and capabilities is unique to the climate-related CBDRs. No other MEA has included provisions stating that developed countries should ‘take the lead’ in meeting the objective of the legal agreement. ¹¹² Since its inception, CBDRs in the climate regime have included the concept of a leadership role for developed countries in action for climate change. The UNFCCC explicitly notes, immediately following its statement on differentiated responsibilities and capabilities in Article 3, that ‘accordingly, the developed country Parties should take the lead in combating climate change and the adverse effects thereof’. ¹¹³ The reasons justifying both differentiation and the consequent leadership role are disputed. Developed countries favour the notion of capabilities and development needs, while developing countries favour the notion of historic contributions. ¹¹⁴ Either way, differentiation within the UNFCCC initially meant that developed countries would adopt national mitigation policies to demonstrate that they are taking the lead in modifying long-term trends in climate change. ¹¹⁵

Under the UNFCCC, parties agreed that, as part of this leadership role, developed countries should adopt mitigation actions to return their GHG emissions levels – individually or jointly – to 1990s levels by the year 2000. ¹¹⁶ There was, therefore, agreement on two points: firstly, that developed countries would assume a leadership role in meeting the central obligations of the treaty; secondly, that this leadership role entailed urgent mitigation action. The Kyoto Protocol made no mention of developed countries taking the lead on climate action. Yet, it understood the UNFCCC leadership role as granting exemption to developing countries and setting exclusive mitigation commitments to developed countries, at least for the foreseeable future.

This translation of the content of the leadership role of developed countries from the UNFCCC to the Kyoto Protocol has been fiercely disputed. The contention centred primarily on the fact that under the UNFCCC regime no meaningful participation was required from key developing countries, not even from emerging economies, on the issue of mitigation. ¹¹⁷ The notion of developed countries taking the lead was never at the heart of the dispute.

Although the stark binary division of the UNFCCC and Kyoto Protocol model of CBDRs has softened, the differentiation in the climate regime as reflected in the Paris Agreement still remains significantly stronger than it is in other MEAs. It is true that the Paris Agreement makes no reference to the early divide between Annex I and non-Annex I parties. The static nature of differentiation in the UNFCCC and Kyoto Protocol has given way to a dynamic differentiation with at least an expectation of future convergence over time. Yet, the Agreement still includes various explicit references to CBDRs, indicating that the principle is maintained as the ‘anchor provision’ ¹¹⁸ of the climate agreement and serves as a guide to evaluate its implementation. ¹¹⁹ CBDRs appear in the Preamble to the Paris Agreement and in Article 2 (goal of the Agreement), Article 3 (communication), and Article 4 (mitigation).

The concept that developed countries should ‘take the lead’ in climate action is also still markedly present. Under the Paris Agreement, while developed countries should expressly ‘continue taking the lead’ by immediately undertaking economy-wide absolute emissions reductions, developing countries should ‘continue enhancing their mitigation efforts’ and are ‘encouraged’ to move towards economy-wide reductions over time. ¹²⁰ Developed countries are still the only parties legally required to provide funding for climate action in developing countries, although, for the first time in the history of MEAs, language was introduced to encourage those developing countries ‘able to do so’ to also provide funding and assistance for less developed countries. ¹²¹

The compromise in the Paris Agreement is to combine universal responsibility, a leadership role for developed countries, and self-differentiation. The requirement that developed countries will still lead the efforts to address climate change indicates that, although there is some room to self-define the extent of this leadership, it is not unlimited. Developing countries still have normative grounds to press for more significant climate action from developed countries. The concept of ‘leadership’ is undoubtedly vague. However, is it so vague as to have no practical application? As the Urgenda decision shows, despite the vague nature of the concept ‘to take the lead’ in the climate regime, this core aspect of differentiation may have sufficient persuasive force to be used as a complementary tool in the interpretation of national obligations.

6. CONCLUSION AND FUTURE PROSPECTS

This article discussed how a national court in the Netherlands broke new ground by using the IEL principle of CBDRs to help in determining the scope of the Dutch government’s duty of care to protect its citizens against climate-related risks. It highlighted how the Court pushed the boundaries of legal thinking by using CBDRs as an interpretive aid to overcome common barriers to liability related to the multi-scalar nature of the climate change problem, such as the difficulty of proving ‘but for’ causation, and the ‘political question’ doctrine. It argued that the Court relied on one element of the principle of CBDRs – the leadership role of developed countries – which has remained fairly consensual, if vaguely circumscribed, throughout the contested history of the global climate regime.

The Dutch government has appealed against the decision. Time will tell if the Court of Appeal will uphold Urgenda, and whether it will also engage with CBDRs in its reasoning. Can other national courts follow the Urgenda lead and use CBDRs as an interpretive tool in concrete cases, or will the Urgenda decision remain an exceptional, isolated case? Dutch courts have a strong record of interpreting national law in conformity with EU law, including environmental law, and are therefore more inclined to engage with IEL. ¹²² Dutch courts have a history of liberally engaging with indeterminate MEA norms, including non-binding provisions. ¹²³ They also have a strong record of using international law to review the exercise of discretionary power by the executive. ¹²⁴ All these characteristics may indicate that Urgenda could remain an exceptional example of a progressive court engaging with CBDRs.

Yet, some recent developments in climate litigation indicate otherwise. In 2015, a civil suit inspired by Urgenda was presented against the Belgian federal government by the Belgian non-governmental organization (NGO) Klimaatzaak. ¹²⁵ As with Urgenda, Klimaatzaak relies on negligence to petition the court to order the Belgian government to increase its efforts on climate mitigation. The plaintiffs argue that industrialized countries, including Belgium, have assumed a leading role in the mitigation of GHG emissions, and their climate action should be fast and significant. ¹²⁶ As in the Urgenda case, the Klimaatzaak litigation argues that Belgium has recognized that the target reduction of 25% to 40% by 2020 represents its fair share of mitigation. Although Klimaatzaak, unlike Urgenda, did not expressly mention CBDRs in its summons, the Belgian court will need to address arguments which are intrinsically linked to CBDRs. The case is expected to be decided by the end of 2016. Another case based on Urgenda has been initiated in Norway. ¹²⁷

It is possible that only national courts in European countries, which are used to engaging with supranational EU law, will be receptive to using CBDRs as an interpretive tool for national obligations. Yet, even in the US, which has a weak record of judicial engagement with IEL, a national court has been clearly inspired by Urgenda. In Juliana v. United States, initiated on 12 August 2015 before the US District Court for Oregon, 21 young American citizens asked the Court to order the government to protect their constitutional rights by adopting a recovery plan to significantly reduce the nation’s carbon dioxide (CO₂) emissions. ¹²⁸ The US government asked the Court to declare the case non-justiciable, citing among other reasons the ‘political question’ doctrine, and argued that action in the US alone would not redress the plaintiffs’ problem. Responding to this line of defence, Magistrate Judge Thomas Coffin rejected the ‘political question’ doctrine in this case, referring to Urgenda, quoting the following passage:

[T]he state should not hide behind the argument that the solution to the global climate problem does not depend solely on Dutch efforts. Any reduction of emissions contributes to the prevention of dangerous climate change and as a developed country the Netherlands should take the lead in this. ¹²⁹

Judge Coffin concluded that combined reductions in the US and other countries were able to redress the harm alleged in the petition and recommended that the suit proceed to argumentation on the merits. Admittedly, the question of the US leadership role was not directly addressed in this decision. Yet, by expressly quoting Urgenda, an American judge has shown that the Dutch decision does offer persuasive normative arguments that may be used by other national courts when dealing with the multi-scalar problem of climate change, even in countries less prone to engage with IEL. Whether other national courts will follow Urgenda’s example and explicitly engage with CBDRs will depend in great measure on whether future litigants will expressly articulate the principle before national courts. This has not happened thus far. If litigants do embrace CBDRs as a persuasive normative argument, we could well see a more productive and extensive use of CBDRs in climate litigation in the future.