1 Aim and Course of Book

Building on a comprehensive study commissioned by the German Federal Environmental Agency in 2018, this book seeks to identify the legal preconditions of the liability of private enterprises for transboundary environmental damage. This goal required an accurate description of the situation de lege lata, i.e. an examination of whether and if so, to what extent existing norms and institutions in international and national law can adequately and effectively address transboundary environmental damage caused by economic actors. However, such an examination would be both incomplete and soon outdated if current and emerging legal developments along with their implications were not also considered in appropriate depth. In addition to the stated goal of identifying existing legal norms and principles, this book has simultaneously endeavoured to focus on current scholarly debates, legal controversies and policy discussions about how liability for environmental damage could and should evolve de lege ferenda.

The present research has pursued these objectives by looking at a very broad and varied range of legal systems, fora, environmental issues and debates regarding liability for environmental damage. Problems of corporate liability concern numerous legal issues touching, inter alia, international and national public environmental law, human rights and constitutional law, private international law, national tort and corporate law as well as issues such as jurisdiction and choice of law. Factoring in this list of legal issues also requires a detailed understanding of the diverse environmental problems and various governance systems already in play regarding corporate liability. However, given the sheer number and variety of relevant issues and the complexities involved, the somewhat selective framing of the subject matter of this study was unavoidable.

Having said that, all involved in this research believe that the choice of the legal systems, concepts and challenges set out in the preceding eight chapters do indeed cover the most relevant issues. The book begins with a brief introduction to the goals and functions of environmental liability and a summary of standard models, specifically in ‘law and economics’ before considering how liability functions (Chap. 2). From here, this research turns its attention to the pertinent concepts and principles of public international law (Chap. 3) where the relevant aspects of international law on State responsibility and liability have been analysed. Proceeding further, the increasing interrelations between human rights and environmental law, as well as current debates and initiatives regarding the international legal status of transnational corporations and other enterprises (Chap. 4) have also been examined. The next chapter focuses on existing specific liability regimes established by individual international agreements, analyses their substantive content and identifies the addressees of the respective obligations (Chap. 5). The potential of using national law to tackle civil liability for transboundary damage (Chap. 6) has also been detailed before an analysis is offered regarding specific regulatory options, de lege ferenda, for anchoring environmental due diligence obligations in national home State laws (Chap. 7). These laws, which are effective across State borders, may serve, inter alia, as a standard of care for civil liability claims in transnational value chains. Finally, open questions and practical legal problems regarding climate change litigation as a reference area for environmental liability are addressed and assessed (Chap. 8) before the preconditions and design options with respect to the increasingly important problem of geoengineering are put under the microscope (Chap. 9).

Given this plethora of issues and challenges, it should come as no surprise that the findings presented here draw a multi-faceted picture of the conditions and prospects of international liability for environmental damage. Rather than proposing a systematic arrangement of coherent norms and principles, the argument is made here that it is possible to identify trends in the dynamic evolution of specific norms and concepts in various legal spheres. This may, at first glance, seem less than ideal given the existing pessimism about the power of international law to avert environmental collapse.Footnote 1 However, a dynamic evolution currently underway offers more than meets the eye and cautious optimism is justified for many reasons, including historical comparison: In the first study on international environmental liability commissioned by the Federal Environmental Agency published 22 years before the present analysis, Wolfrum and Langenfeld came to a rather sobering conclusion that there was little likelihood of any significant evolution in international environmental liability law in the foreseeable future. Apart from selective progress in the development of international environmental liability, which was limited to specific legal sectors, they found little reason to predict there would be any significant evolution in the field.Footnote 2 Prima facie, our analysis of the legal situation seems to support such a disillusioned diagnosis. A closer look at a broader range of legal phenomena and dynamics, however, arguably justifies a more expectant outlook as legal inertia has given way to considerable impetus.

2 Tendencies: Convergence of Human Rights and Environmental Law as the Main Driver of Legal Development

According to the present analysis, this more optimistic outlook is not based on the development of genuine environmental liability rules for private parties in international law per se. However, an assessment of the status of corporate liability for transboundary environmental damage that solely looks at the slow progress in international environmental law would create an erroneous perception. Significant trends have emerged concerning two interrelated factors beyond the realm of the rules and principles of international environmental liability. First of all, there has been a shift in normative development toward the domestic level. This is evidenced by businesses’ obligations to prevent, restitute or compensate for transboundary environmental damage now being regulated by States using domestic laws with extraterritorial effect and national enforcement mechanisms. Secondly, given the historic intransigence of international law to change, a dynamic evolution of international environmental liability now taking place at the intersection of human rights and environmental law is both remarkable and arguably unprecedented. This dynamic is predominantly driven by national and international courts and other decision-making bodies as well as by national legislation. It may point to the emergence of an environmental standard of care which can be referred to, inter alia, by national civil courts around the world to determine the liability of corporations and other businesses for transboundary environmental damage.

Having said that, an isolated consideration of the current state of international environmental liability law seems to indicate little progress is being made. This assessment is supported, first of all, with respect to the general question of whether international corporations and other businesses can be regarded as duty-bearers under international environmental law. With the notable exception of UNCLOS (Chap. 13 ¶ 15 et seq (Sect. 13.2.3)), none of the rules and principles of international environmental law analysed in this book, be they general or more specific, are directly binding on international corporations and other businesses. This, of course, does not imply that international law is irrelevant for these private actors. Indeed, the increasing specificity of environmental as well as product-related norms regulating environmental risks caused by private enterprises which operate in States other than the State of origin is quite evident, both in terms of hard and soft law. International environmental treaties in particular are increasingly integrating clear and predictable obligations for corporations with respect to specific environmental risks. To become legally effective, however, these obligations still predominantly require implementation and sanctioning by States. The current dynamics of the juridification of environmental norms seem to point to a gradual and selective change in the legal status of private actors. While this is an improvement on the previous state of affairs, international environmental law continues to deal with non-State conduct indirectly, i.e. through the intermediation of domestic law and State action.

The situation de lege lata regarding State liability and responsibility may also seem to support a sceptical outlook regarding the chances of there being any significant evolution of international environmental liability law. For example, current plans to interfere with the climate system via geo- and climate engineering indicate that there is a clear need to agree on standards for international environmental liability, however, the prospects of adopting a relevant treaty instrument are low (Chap. 9). States are reluctant to agree to both the adoption of new and the strengthening of existing instruments concerning civil liability and, as such, this reticence becomes even more entrenched regarding new instruments addressing State liability.

The liability of States for transboundary harm is neither a de lege lata nor ferenda option due to the general unwillingness of States to accept any liability for lawful but harmful acts. This unwillingness persists despite State responsibility for the violation of the no-harm rule being widely accepted as customary international law. It is State responsibility that, according to our analysis, should be the first vehicle driving the development of international norms focusing on extraterritorial instruments and obligations. While the practical relevance of the rule is rather limited, the normative relevance of the no-harm rule, which contains due diligence obligations for States towards the environment, is undisputed. Measured against the total amount of transboundary environmental damage subject to the no-harm rule, both the number of cases and the portion of that damage ruled on by international courts and tribunals have remained low. The Rio Declaration, including the principle of prevention, is now almost 30 years old but its real-world application remains a matter of potential rather than fact. Customary international law still does not recognise any general duties of home States to ensure companies under their jurisdiction use their management control instruments to prevent environmental harm in the host States. This is particularly problematic in cases where environmental harm does not also impair human rights. Consequently, State responsibility only covers cases where environmental harm originates from the home State’s territory (Chap. 3).

However, and despite its limits, the no-harm rule still has great potential for legal development, all the more so since the ICJ, among others, has proven in the last few decades that it can be very dynamically applied. With a view to these prospects, it is argued in Chap. 3 that the combined environmental principles of both polluter-pays and prevention have the potential to bring about a new rule according to which States must ensure that public and private polluters ultimately bear the cost of their action or inaction. This rule would see States lose the ability to selectively and arbitrarily exclude public and private polluters from their environmental responsibility and liability. A comparison of existing international civil liability regimes and related non-binding instruments makes it possible to identify similarities regarding relevant normative concepts and preconditions of environmental liability and provides useful insights into how more specified regimes of civil liability for environmental damage may be shaped in the future (Chap. 5). While existing civil liability regimes reflect the polluter-pays principle, this principle does not legally prescribe any specific liability model when addressing environmental damage. Instead, it sets the ultimate goal that the polluter bears the cost of the damage caused by the pollution via different liability and remediation tools available under international and national law, e.g. by choosing a civil, administrative or criminal liability model, or a combination thereof. This makes further development of the combined principles of prevention and polluter-pays, which will limit unreasonable polluter-protective legislation, all the more important.

The shift to States’ obligations to regulate companies whose operations have negative extraterritorial impacts would be facilitated by further development of the prevention principle and the polluter pays principle. In contrast to international environmental law, human rights law is already cautiously embracing a duty for home States to ensure that companies subject to their jurisdiction use their corporate influence over suppliers and subsidiaries to ensure respect for human rights standards in host States.Footnote 3 Given the sobering track record of international cooperation on pressing issues of environmental degradation, such juridical progress on international obligations towards the environment is long overdue and very much in line with the objectives and functions of both human rights and international environmental law. It is also not unduly demanding to require States to comply with broadly accepted procedures to assess risks of extraterritorial human rights violations, to observe global scientific consensus about indispensable measures to prevent environmental catastrophes and to issue adequate regulations to prevent corporations under their jurisdiction from contributing to serious human rights abuses.

Such juridical progress can be explained and gain relevance as the overlap between environmental law and human rights grows, a process that may be seen as both regime congruence and regime convergence. The concept of regime congruence was proposed by Banda to grasp the productive mechanisms of mutually supportive regimes in cases where two bodies of law seek to regulate the same subject matter.Footnote 4 Regime convergence refers to an integration of legal concepts, principles and doctrines by separate regimes which potentially broadens the intersection of their normative scopes and, thus, also increases regime congruence.

Many of the cases and debates described in this book refer to productive intersections between human rights and environmental law in line with the idea of regime congruence. Human rights litigation is increasingly willing to integrate primary environmental norms and standards to define a standard of care that shapes the content of what duty-holders of human rights owe to individual rights-holders.Footnote 5 As obligations of conduct to prevent rights violations human rights obligations are not breached simply because environmental damage has occurred.Footnote 6 In contrast, courts have to clarify the normative standard to determine whether the conduct of a State was adequate in light of the given risks to human rights. The fact that courts now seem to be willing to establish this standard of care by drawing on general principles, substantial and procedural obligations according to international environmental law as well as international soft law, can be viewed as one of the most promising aspects of the transformative spread of ideas we are currently witnessing across in human rights and environmental law.Footnote 7 For example, courts and other decision-making bodies have specified that the precautionary principle is conclusive for determining whether a State has complied with its obligations to protect human rights and delineates States’ duties to prevent violations of human rights arising from environmental harm caused by private actors under their jurisdiction (Chaps. 3, 4 and 8).Footnote 8

As a consequence of regime congruence, recourse to human rights may improve the chances of meaningfully enforcing transnational environmental norms and standards. Conversely, by integrating core environmental norms into a human rights-based standard of care, the content of what measures are required to meet human rights obligations in the face of environmental risks is substantiated. Thus, human rights law, which more readily facilitates individual claims than environmental law, has the potential to give “teeth to the international environmental law regime”.Footnote 9 Access to justice in instances such as those related to climate change litigation (Chap. 8), may result in the strengthening and extending of environmental rights and obligations. Judgments, decisions and legal opinions, such as the much-debated advisory opinion of the Interamerican Court of Human Rights on the Environment and Human Rights,Footnote 10 support the assumption that substantial human rights law is indeed “capable of evolution in its understanding of extraterritoriality and would support the application of human rights treaties to transboundary environmental harm” (Chaps. 3 and 4).Footnote 11

Traditionally, such productive intersections have been limited due to a narrow understanding of the interdependency of human rights and the environment.Footnote 12 Environmental interests without direct and imminent connection to life, health or property are, at least under most human rights instruments, not considered as protected by human rights. Mediated or dispersed harm, particularly if it affects a large number of people in a wide area, can often not be translated into an issue of human rights law. Many of the cases examined in this book, however, illustrate that national and international courts, as well as other authorities, are very much prepared to interpret the scope of protection of human rights guarantees in ways that make it possible to understand impairments due to environmental problems or climate change as human rights violations. The legal debate on the existence, scope and content of environmental human rights is now increasingly focused on potential avenues to strengthen the intersections between human rights, climate and the environment. Most prominently, this is emphasised by advocating the existence of a human right to a healthy environment. In a similar vein, a recent decision by the Inter-American Court of Human Rights illustrates how a version of collective environmental rights could take shape when the Court found that there had been a violation of, among other things, a right to a healthy environment for indigenous peoples.Footnote 13 The recent decision of the German Federal Constitutional Court on the German Climate Protection ActFootnote 14 points to another opportunity to strengthen the link between the environment and human rights. Here, the Court recognised an intertemporal dimension to fundamental rights which may require avoiding future violations of rights due to a present deficit of legal instruments to protect both the climate and environment. This emergence of an intertemporal aspect could further contribute to a significant expansion of redress against environmental damage. Such decisions prove that the increasing scientific certainty of the existential importance of environment and climate on human rights is already being reflected in a certain degree of disruption in traditional doctrines and the embrace of new legal ideas.

It remains to be seen to what extent environmental standards of care derived from and developed for constitutional and human rights purposes will become relevant for issues of the liability of transnational corporations and other businesses. There are numerous indications, however, that the productive interplay between human rights with environmental norms and standards will increasingly reverberate in cases involving transnational tort litigation before national civil courts. National tort law, as the most important “enforcer of human rights”Footnote 15 in relationships between private actors, seems very much able to take up and further evolve regime congruence between human rights and the environment.

Recent case law is an example of how international human rights, in both hard and soft law, can become relevant for national judges as a starting point to develop environmental standards of care. Prominent cases of climate litigation indicate that national judiciaries may be better placed to look at duties of care than international courts whose ability to move beyond the merits is limited by their jurisdiction. This can be demonstrated by reference to relevant cases decided by Dutch, Irish and German courts where judgments explicitly referred to resolutions and decisions of Human Rights bodies. Landmark cases (e.g. Urgenda, Shell and similar cases in the US) point to the potential of national tort law regimes to integrate certain standards, such as scientifically proven and internationally endorsed greenhouse gas emission reduction targets, as a basis for private duties of care (Chap. 8). Even if many individual questions remain open and confronted by obstacles, especially in private international law, substantive civil law does not seem to be plagued by insurmountable obstacles that prevent it from dealing with more cases in the future. Importantly, doctrines of fault-based liability in national tort law regimes are able, in principle, to deal with transboundary environmental damage arising from activities in global value chains involving various and diverse actors. The standard of care, given substance by civil courts on a case-by-case basis, can integrate environmental norms and standards from various sources to determine a defendant’s obligations to prevent harm (Chap. 6).

The development of the transboundary environmental liability of corporations and other businesses can also be driven forward by domestic legislation which, currently, constitutes the epicentre of legislative dynamics regarding the transboundary liability of private actors. Home State regulation (Sect. 7.2) plays an important role in the evolving convergence between human rights and environmental protection. Most importantly, as described in detail in Chap. 7, new legislation and current proposals require corporations to carry out specific due diligence procedures to prevent infringing human rights and harm to the environment arising from activities in their global value chains. During the preparatory stages of this book, there was remarkable political and legislative momentum in this area, a phenomenon that has persisted to the time of completion and shows little sign of slowing. The adoption in 2021 of the German Supply Chain Due Diligence Act, the Norwegian Transparency Act and the development of drafts for an EU Directive by the European Parliament, coupled with the European Commission’s proposal on corporate sustainability due diligence in 2022, are arguably the most striking examples of this legislative trend.Footnote 16 From an international perspective, such approaches may be seen as measures by States to discharge the potential, albeit still contested, obligation to adopt ex ante legislation to prevent damage to human rights and the environment.Footnote 17 From the perspective of national civil liability regimes, these laws could strengthen and specify a minimum standard of care for domestic businesses and ensure access to justice for victims of environmental damage. In doing so, these efforts could fill, or at least minimize, remaining gaps in national liability regimes for transboundary environmental damage. The integration of civil liability clauses in some of these regulations to enable victims of transboundary harm to seek redress before home State courts thus seems particularly consequential.

Even though a healthy scepticism towards regulatory instruments relying on traditional home State control may be justified,Footnote 18 the emerging trend towards extraterritorially effective home State regulation is presented here as a plausible approach to simultaneously meet the international requirements of the polluter-pays principle, the prevention principle and human rights obligations. The fact that national regulations often do not meet the requirements of these standards does not undermine this theoretical potential. The urgent need for ambitious and globally coordinated measures, however, highlights the necessity for States’ domestic regulation of business enterprises with extraterritorial effects to be rooted in international law. In this respect, too, current developments are pointing the way. The open-ended intergovernmental working group on transnational corporations and other business enterprises with respect to human rights (OEIGWG), established by the UN Human Rights Council, initially pursued relatively radical innovations aimed at establishing direct human rights obligations for transnational business enterprises. However, it mollified its approach in more recent drafts that now emphasise States’ extraterritorial duty to regulate human rights risks caused by the behaviour of their citizens. The drafts also emphasise that the notion of human rights abuse includes any harm which impedes the full enjoyment of the right to a safe, clean, healthy and sustainable environment while also making clear that obligations to prevent such harms should be enforceable in home-State courts via transnational tort litigation (Chap. 4 ¶ 39 et seq, ¶ 70 (Sects. 4.2.3 and 4.3.3)).

3 Prospects: An Emerging Transnational Environmental Standard of Care?

The evolution of what can be defined as a transnational environmental standard of care could be seen as one of the most striking developments in the context of environmental liability law. Notwithstanding the many differences between the cases and legal constellations considered in this book which concern different parties, legal institutions, fields and levels of law, a number of common features can be described in terms of an environmental standard of care.

The normative foundation of the standard of care lies in environmental human rights and their relation to fundamental rules and principles of environmental law, such as the prevention principle and the precautionary principle. This standard of care is transnational as it potentially covers and further develops norms on both the national and international levels as well as private norms and standards. These rules and principles, whether specified in transnational private standards, home State norms or binding or non-binding international norms, are increasingly considered to reflect legally relevant norms and expectations with respect to corporate accountability.Footnote 19 As such, they are legally relevant reflections of what is considered the standard of care that is necessary and feasible to prevent damage.

This inclusive nature of the standard of care may be explained by a range of conceptual properties: In particular, it refers to substantial standards, rules or principles (‘primary norms’, cf. Chap. 2), but does not necessarily by itself constitute a primary norm. In other words, the respective substantial standard depends on and is substantiated by a primary obligation, which applies to the defendant and is directed at protecting a right or legal interest. Climate litigation (Chap. 8), for example, illustrates how a standard of care addressing private entities will differ, depending on the underlying legal norm. While the Client Earth v. Enea case concerning directors’ duties (Chap. 8 ¶ 120 (Sect. 8.3.3)) demonstrates that climate change is already creating and influencing the standard of care in the internal relationship between shareholders and corporate management, the standard of care in other cases is entirely different in character and may, for example, be directed to the protection of the general public (see e.g. the Shell case).

The most auspicious candidate for an overarching standard of care is the concept of value chain due diligence specified by the UN Guiding Principles on Business and Human Rights (UNGPs); incrementally, the Guiding Principles can be seen as the “global authoritative policy standard” to address governance gaps in business enterprises’ global value chains.Footnote 20 Due diligence in this context has been defined as the “comprehensive, proactive attempt to uncover human rights risks, actual and potential, over the entire life cycle of a project or business activity, with the aim of avoiding and mitigating those risks”.Footnote 21 Notwithstanding its original focus on international human rights, this concept, as Chap. 7 analyses in great detail, can be transferred to a model which regulates environmental risks beyond their overlap with human rights. Recent approaches to home-State regulation (¶ 17 et seq; Sect. 7.2) integrate such environmental due diligence obligations as a separate requirement to human rights due diligence. While, under liability law, due diligence can form a specific standard of care,Footnote 22 it is neither a civil law nor a public or administrative law concept per se but a much broader, cross-cutting approach (Sects. 6.2.5 and 7.3).

Due diligence obligations are purposely designed to leave a substantial margin of discretion for businesses, authorities, and ultimately courts. First of all, due diligence in this sense typicallyFootnote 23 defines a behavioural standard of conduct (not of result). In accordance with the precautionary principle, duties of conduct in environmental law have the function of enabling risks in complex and uncertain situations to be adequately handled. They are supposed to provide normative commitments and at the same time enable agents to adapt and adopt preventive measures to manage risks and exercise options for action in political circumstances which may realize in an a priori unpredictable manner. Having said that, as a predominantly procedural standard of care, due diligence contains requirements to ensure that operations taking place in the legal context of environmental risks are carried out in a well-organised and hazard-minimising manner. Again, this is meant to provide the relevant actors with sufficient room for manoeuvre to deal with future unknown or non-specific risks and hazards.Footnote 24

At the same time, it is important to emphasise that due diligence is not merely a tick-boxing exercise but can result in substantive obligations to avert an identified risk of harm or to mitigate imminent harm. As a substantive standard of care it includes the prohibition for a business to cause harm through its own activities and the duty to prevent harm,Footnote 25 but may also oblige them, for example, to implement certain technical measures or instructions to minimise negative environmental effects and refrain from the use of particularly hazardous substances. A proportionality test serves to determine the required level of due diligence in a flexible manner concerning the specific circumstances of the individual situation.

Due diligence forms a promising basis for the development and extension of a transnational standard of care. Conversely, liability law can be seen as a particularly suitable mechanism to further substantiate the open and procedural requirements of due diligence for specific transnational and sectoral contexts. There are several reasons, why legal doctrines of national liability law seem to be particularly appropriate tools to implement and further develop environmental due diligence, especially with respect to transboundary environmental damage.

First of all, scholars have frequently highlighted the specific potential of civil liability as an instrument of transnational norm-production. Norms and standards in international environmental agreements and soft law and, to a certain extent, the internal standards of transnational companies that reflect their own tried and tested practice as well as industry-wide self-regulation, can turn into legally relevant manifestations of a necessary and feasible standard to prevent damage. Second, fault-based liability, in line with a due diligence standard, requires a proportionality test and allows for the construction of very detailed and context-sensitive standards. Importantly, fault-based liability specifies the relevant duties through balancing interests in individual cases from an ex post perspective. Its standards are, at least to a certain extent, shaped by the contributions and deliberations of the parties to a dispute about the particular facts and the appropriateness of measures that would have prevented the damage sustained. It is, therefore, able to constantly adapt standards of reasonableness in view of current social needs and scientific findings.Footnote 26

As a consequence of the normative openness and context-sensitivity of a tort-based construction of a standard of care, liability law provides fine-tuned approaches to the attribution of liability in situations where spheres of risks and scopes of action overlap between diverse actors. This allows it to not only address constellations of transboundary environmental damage where harm arises abroad directly as a result of the transboundary effects of a tortfeasor’s conduct but also, in principle at least, provides legal solutions for cases in which a defendant’s domestic actions only indirectly contribute to damage abroad. Even though courts have so far been reluctant to find liability in cases of harm directly caused by subsidiaries or suppliers in transnational value chains, the increasing recognition and legal implementation of due diligence obligations as envisaged by the UNGPs may lead to this reluctance being increasingly abandoned.

Finally, tort law principles may also provide some orientation regarding the allocation of environmental responsibility between public and private actors in transnational constellations, an issue that is still not settled in international law. A standard of care under liability law allows for an understanding of common but differentiated obligations towards the environment which, as we have seen, cannot currently be deduced from international environmental law. It is argued here that the overlap of State and private duties remains an issue to be examined in further research, however, some indications exist that transnational standards of care applicable to private actors on the one hand and States on the other also increasingly converge. Recent climate litigation in civil law cases is proof of the possibility to hold private entities liable based on the same legal standards that define State duties. For example, the standard of care in Milieudefensie v. Shell was derived, inter alia from the reduction targets of the Paris Agreement (see Chap. 8).

4 Challenges: Ways Forward for a Transnational Environmental Standard of Care

Notwithstanding the dynamics explicated above, major gaps in environmental liability law remain. This is noteworthy and illustrates the lack of political space for international rules to capture and balance measures able to tackle transboundary environmental challenges caused by globalisation.

Well-targeted regulatory approaches should be purposely construed to address legal loopholes that became apparent in environmental liability cases. As shown in Chap. 6, the assertion of transboundary damage claims can be averted by disadvantageous, or at least unclear, rules in private international law. Specifically, in cases against corporations concerning environmental damage directly caused by their suppliers or subsidiaries abroad, domestic courts will often apply foreign tort law, which can be disadvantageous from the perspective of the injured party. Many lawyers also believe that domestic regulations and standards should only be relevant to the liability of European companies if such regulations exonerate them. These views are at odds with the sought after goals of effective transboundary environmental liability, namely, to prevent companies from strategically exploiting ‘pollution havens’ abroad. Domestic regulations exonerating companies also contradict the fundamental principles of European conflict of laws, which is intended to raise the overall level of environmental protection by enabling the victims of environmental damage to choose the applicable law and thereby opt for a more comprehensive standard of care. Given both the sheer scale and global implications of environmental damage caused in transnational value chains, such obstacles to effective transboundary environmental liability should be removed.

In addition, the anthropocentric focus of liability law continues to exclude environmental damage that does not simultaneously affect clearly defined human rights, such as those related to property, health and life. From the perspective of legal policy, several possibilities are conceivable to broaden the scope of environmental liability to address this: First, administrative liability and other ‘top-down instruments’ could be strengthened to implement an environmental standard of care. In principle, administrative liability, if applied effectively,Footnote 27 can accommodate restrictions to environmental liability regarding pure environmental damage and its dispersed or delayed effects.Footnote 28 In many transnational constellations, however, administrative liability may be rather weak and not the instrument of first choice.

Scholarly debates on how the understanding of the intersection between human rights and the environment could be broadened in the context of tort law have not been pursued since the early 2000s. It remains to be seen whether and in what way the intense dynamics regarding the convergence of human rights and the environment will have an impact on tort law. Recent decisions of human rights and constitutional courts, which further specify the scope of subjective rights in the face of imminent risks, as well as legislative projects focusing on environmental and human rights due diligence may provide the needed impetus for new attempts to broaden the contexts in which tort law operates.

Even though the view presented here is that doctrinal and epistemic problems can be solved in many fields, the proof of causality of a breach of duty for the occurrence of damage remains a cardinal problem for civil environmental liability. Legal doctrine and case law both indicate that challenges in attributing responsibility/liability for complex issues, such as climate change and geoengineering activities, can be overcome in many cases. Approaches that have been applied in case law to date, in particular the ‘preponderance of evidence’ standard, seem to be sufficiently flexible in this respect (Chap. 9) and national civil law could certainly accommodate these developments. Traditional principles which make it possible to facilitate, or even reverse the burden of proof, may sometimes support plaintiffs’ causes. Problems of attribution of damage will remain, however, a source of considerable procedural uncertainty and may, in many cases, inhibit effective environmental litigation.

Targeted regulatory approaches can, in principle, solve these problems. Some of the proposals and implementations of a home State regulation to establish corporate due diligence already address major obstacles to effective transnational environmental liability. The proposals for an implementation of a value chain regulation, analysed in Chap. 7, include explicit references, inter alia, to international environmental law in this sense. In addition, detailed due diligence procedures ‘preform’ an ex-post standard of care in accordance with international concepts of human rights due diligence. Such statutory obligations clarify that adequate risk analysis and prevention throughout the value chain are legally relevant for a corporation’s risk of liability and where such obligations cannot be circumvented by simply relinquishing control and supervision of the activities of suppliers and subsidiaries. However, further juridification of international environmental law remains crucial beyond the extraterritorial approaches already discussed and is also of great importance for the further development of environmental liability. Environmental regulations, such as the prohibition of the unnecessary use of hazardous substances or very high-risk activities, remain an indispensable preventive instrument to control transboundary environmental pollution. As an element of fault-based liability, and of other enforcement mechanisms, ex ante-regulation also provides supplementary primary norms and standards while delivering additional information about the adequate preventive measures to be taken into account by courts to determine the standard of care.

Multi-level legal dynamics require and are highly likely to lead to multi-level legal strategies. The interactions between different legal levels in the development of an environment-related standard of care will also necessitate legislative activity on all these levels. Unilateral action by States does not necessarily mean that the objective to establish a global level playing field has been rejected. Notwithstanding the prominence of national fora in current proceedings and debates surrounding transboundary environmental liability, the global nature of existing environmental problems also requires global substantive and protective standards. Environmental policy does not have to choose between an exclusively preventive strategy building on ex ante regulation on the one hand and ex post-liability mechanisms on the other. The advantages of liability law to contribute to the development of adequate and specific standards of care in cases involving transboundary damage, however, are evident. Environmental policy, which must endeavour to solve such global problems should harness this potential and translate it into real-world results.