2. Procedures and Evidence

I Australia

In Australia, there has been a noticeable shift in how courts address evidence and causation. Initially, linking individual projects to specific climate impacts was challenging, but over time, courts have increasingly recognised the relevance of scope 3 emissions and the significance of single projects, assessing emissions cumulatively. The acceptance of climate change science, notably through the Intergovernmental Panel on Climate Change (IPCC) reports, has played a pivotal role in the evolution of how courts address evidence and causation, as seen in the Sharma case, which proceeded on a Statement of Agreed Facts.

Despite these advancements, legal tests for causation remain a hurdle. For example, the "market substitution" argument complicates proving the impact of specific projects on net greenhouse gas emissions by suggesting that rejecting one project will not affect overall emissions due to similar projects developing elsewhere. Nonetheless, some courts have dismissed this line of reasoning, as seen in Waratah Coal Pty Ltd v Youth Verdict Ltd & Ors and Gloucester Resources Ltd v. Minister for Planning. Additionally, other judicial opinions, like in Sharma v. Minister for the Environment [2021] FCAFC 56, suggest that traditional legal concepts may no longer be adequate for navigating the complexities inherent in climate litigation. One approach to overcoming evidentiary challenges in climate litigation could involve reversing the burden of proof. Instead of requiring claimants to demonstrate their risk of harm from climate change, the responsibility could shift to defendants—those in a better position to mitigate climate change—to prove that their actions do not contribute to the harm experienced by claimants.

II Brazil

Article 332 of the Civil Procedure Code recognises a variety of evidence forms, including personal and expert testimonies, documents, to prove facts in legal actions. In environmental litigation, the National Council of Justice (CNJ) [provides rules] on the use of remotely sensed data and satellite information, while the Law of Popular and Class Action enables individuals to obtain documents from public entities before legal proceedings. Judicial inspections and expert evidence are vital, especially for complex environmental cases requiring scientific insight. The CNJ's Resolution 433 and public consultations aim to develop methodologies for assessing environmental damage, including the use of the Carbon Calculator by the Amazon Environmental Research Institute (IPAM) and the social cost of carbon principle to quantify damages from deforestation and pollution. These efforts are supported by the principle of shifting the burden of proof to the polluter, as established by the Brazilian Superior Court of Justice's Precedent 618, ensuring that polluters must demonstrate the absence of harm they have caused, aligning with the "polluter-pays" principle.

III Canada

The efficacy of sources of evidence and procedure related to causation remains to be fully tested in the Canadian legal system as corporate climate litigation evolves.

Generally, negligence claims involve establishing both factual and legal causation. Factual causation requires plaintiffs to prove harm would not have occurred "but for" the defendant's actions or omissions, using a "but for" test. If factual causation is established, plaintiffs must then prove legal causation, which considers the foreseeability of the harm and whether the harm is too remote to be attributed to the defendant. In cases where it is challenging to pinpoint a single tortfeasor's action as the cause, a "material contribution" test is applied. This test requires showing that the plaintiff's loss would not have occurred but for the negligence of two or more entities without needing to apportion fault among them. Therefore, the "material contribution" test might be useful in scenarios involving multiple possible tortfeasors in corporate climate litigation.

Future climate-related disclosures may become crucial evidence in litigation, complementing the current use of governmental reports, scientific studies, and expert testimony. Governmental reports detailing efforts to meet greenhouse gas emissions reduction targets can serve as vital evidence for plaintiffs. Similarly, scientific and environmental monitoring reports, along with expert testimony, provide significant evidence that can be leveraged in corporate climate litigation. Consequently, to successfully pursue private law claims against corporations in Canadian courts, there will be a need for enhanced scientific evidence that clearly links harm to climate change.

IV China

In China, the burden of proof and causation are guided by civil procedure law and the Civil Code, particularly in environmental and public interest litigation contexts. For environmental damage, Article 1230 of the Civil Code allows for a reverse burden of proof, where defendants must prove their actions did not cause harm. Moreover, the introduction of Several Provisions of the Supreme People's Court on Evidence in Civil Litigation for Ecological and Environmental Infringement addresses causation issues, emphasising the role of expert assessments and scientific evidence in establishing causation. In the Shenzhen Xiangfeng administrative punishment case, the plaintiff commissioned a report from the Shenzhen Huantong Certification Center LLC regarding the carbon emissions of emission trading institutions in Shenzhen. This report was submitted as evidence for the trial.

Addressing causation challenges in climate change litigation requires significant improvements and adjustments in legal frameworks. Advancements in climate science can mitigate uncertainties by utilising the most current and authoritative scientific evidence, including recent IPCC reports. China's Environmental Protection Law's emphasis on expanding and interpreting the prevention principle, the priority of protection principle and the comprehensive environment governance principle could lead to similar advancements.[9] Applying the risk prevention principle via preemptive litigation may partially address uncertainties related to climate change's effects. Furthermore, it is crucial to revise legal causation doctrines to more accurately reflect the complexities of climate change. The introduction of the concept of joint causation as an alternative to the traditional "necessary causation," along with recognising the shared responsibility of multiple actors in causing environmental harm, is supported by Article 1172 of China's Civil Code.

[9] According to Article 5 of the Environmental Protection Law of China, the prevention principle, the priority of protection principle and the comprehensive environment governance principle are listed as the basic principles of the environmental law in China. Prevention is expressed as "a dominative role" in the Environmental Protection Law of China, which requires preventive measures to be taken to avoid environmental and ecological damage. The priority of protection principle means that protection should be taken as a prioritised task in environmental protection. The comprehensive environment governance principle requires the law to be implemented in a comprehensive manner and with a holistic approach. It welcomes various approaches and a comprehensive, harmonious, sustainable way to deal with environmental problems.

V France

In France, the sources of evidence related to causation in corporate climate litigation have been demonstrated through several cases, with the La Mède refinery case being a notable example. In the La Mède refinery case, the Administrative Tribunal of Marseille invalidated Total's permit to operate a biorefinery, citing an incomplete environmental impact statement, particularly lacking information on climate impacts. Moreover, the existing French climate cases provide an interesting insight into the question of the standard of proof necessary to prove that companies have violated their duty to establish a vigilance plan. Indeed, plaintiffs must not prove that companies have violated their duty with certainty but rather show that the plan is "unreasonable" or "insufficient", which denote two lower standards of proof (see, e.g. the La Mède refinery case" or NAAT vs Total case). Although issues of causation have not been expressly raised in French climate cases to this day, it stems from the analysis of medical and environmental liability law that judges often accept that the causal link may be "probable" or even "reasonable", which resembles the Anglo-American standard of the "balance of probabilities" or the Philippine "reasonable causation link".

VI Germany

In Germany, the burden of proof in civil litigation, including corporate climate litigation, traditionally lies with the claimant, who must establish the causality of a climate change phenomenon to a company's CO2 emissions. Moreover, the standard of proof for causation, as stipulated in Sec. 286 of the German Civil Procedure Code (Zivilprozessordnung; ZPO), seems to require that causation must be proven beyond reasonable doubt, although there is an ongoing debate on this very point. The RWE case exemplifies the difficulties in establishing causation, with courts requiring concrete evidence of a direct link between individual emissions and climate change effects and opting for court-appointed forensic expert evaluations over studies of renowned scientists provided by the parties.

However, a shift towards a presumption of causality based on Sec. 6 (1) UmweltHG has been advocated, placing the onus on defendants in cases where their operations of a plant could inherently cause damage. Additionally, some advocates propose using Section 287 of the ZPO to assign partial liability to large emitters based on their contribution to total anthropogenic carbon dioxide emissions, allowing courts to estimate damages accordingly. However, the prevailing opinion in Germany typically reserves Section 287 of the ZPO for calculating the amount of damages in the remedy phase rather than establishing liability for damages.

VII India

In India, evidence in corporate climate litigation heavily relies on expert reports and analyses, reflecting judges' reliance on specialised knowledge to understand complex climate change issues. Notable examples include the National Environmental Engineering Research Institute (NEERI) and the use of international and national statistical data on environmental pollution and climate change. In Hanuman Laxman Aroskar v. Union of India, the Supreme Court considered the Environmental Impact Assessment Report prepared by a consultant, the Kasturirangan Report of the High-Level Working Group on the Western Ghats, the Airport Guidance Manual published by the Ministry of Environment and Forests, and minutes from Environmental Appraisal Committee meetings to decide on the suspension of the Environmental Clearance for an airport project in Goa.

In the case Court on its own Motion v. State of Himachal Pradesh, the Green Tribunal addressed the impact of climate change on the Rohtang Pass glacier in the Himalayas, experiencing significant pollution and environmental degradation. The tribunal considered various sources of evidence, including the Expert Committee report appointed by the High Court of Himachal Pradesh, a study by the Indian Institute of Forest Management in Bhopal, and statistical data from the World Meteorological Organisation.

VIII Italy

In Italy, corporate climate litigation challenges the traditional approach to causation in legal liability, especially in the context of environmental harm. Unlike compensatory actions that require a direct causal link between specific conduct and specific damage, many corporate climate cases focus on injunctions to prompt action (e.g., emission reductions). These cases necessitate proving a different kind of causal relationship that connects the defendant's conduct not directly to harm but to a continuation or exacerbation of a dangerous state, such as the climate emergency. This adjustment in the causation framework shifts the evidentiary focus towards establishing a link between the defendant's actions and the perpetuation of climate risks, relying heavily on scientific evidence to make this connection.

The IPCC Reports are central to providing this scientific evidence. Cases such as Greenpeace, Re:Common et al. vs ENI exemplify this approach, where claimants utilise conclusions from scientific conferences and IPCC reports to argue that companies like ENI, aware of the climate impacts of fossil fuels since the 1980s, have contributed to the climate crisis.

In non-compensatory actions, such as those aimed at preventing future harm (e.g., Veronesi, Cremonini, ENI, Pasubio cases), the stringent requirement for direct causation proof is lessened, broadening the scope for claimants to argue for preventive measures based on broader scientific evidence and consensus.

IX Japan

In Japan, the Kobe District Court's approach to climate litigation emphasises the traditional burden of proof on plaintiffs, requiring them to establish a causal relationship at a high level of probability. This necessitates robust evidence to support claims, including various IPCC reports, Japan's Meteorological Agency's report on climate change, the defendant's environmental impact statement and CO2 reduction policies, data on estimated CO2 emissions from large coal-fired power plants and other sources, and expert opinions on the general causality between CO2 emissions and climate change.

X Kenya

In Kenya, the legal framework for evidence in climate litigation is governed by the Evidence Act, which places the burden of proof on the party asserting a fact, such as the causation of climate change, by a corporate entity. This burden may shift to the defendant if the plaintiff provides sufficient evidence that meets the court's standard of proof. The court's interpretation of causation in the context of climate change litigation remains to be seen as cases are filed and adjudicated.

XI Netherlands

In the Netherlands, climate litigation leverages a diverse array of evidence, including attribution science reports, IPCC reports, corporate annual and sustainability reports, and data on CO2 emissions from the Carbon Disclosure Project and United Nations Environment Program (UNEP), to establish causation and liability.

Procedural rules for climate litigation are grounded in the Code of Civil Procedure. The court can only consider facts or rights that have been properly presented and established during the proceedings. If facts are not disputed by the other party, they are taken as established unless doing so would result in a legal effect which is not at the free determination of the parties. The burden of proof generally lies with the party asserting facts or legal effects, but this can shift based on special rules or fairness considerations (Article 150 Code of Civil Procedure). Dutch law adheres to the principle of "vrije bewijsleer," allowing courts that assess and establish the facts, i.e., district courts and the courts of appeal, but in general not the Supreme Court, (Article 152 section 2 Code of Civil Procedure) significant discretion in evaluating evidence, aiming for a "reasonable degree of certainty" regarding the existence of facts. This discretion in evidence evaluation, combined with the specific rules on burden and standard of proof, shapes the approach to causation in corporate climate litigation

In Dutch procedural law, the principles of party autonomy and judicial passiveness play a crucial role, allowing parties significant control over the litigation process, including the timing, subject matter, and factual basis of the case. Judges' engagement with technical or scientific matters, such as climate science, largely depends on the evidence and arguments presented by the parties, as demonstrated in the Urgenda judgment by the District Court of The Hague. Nevertheless, Dutch civil courts hold significant discretion in deciding whether to engage court-appointed experts for obtaining necessary expert information, and in evaluating such expert opinions.

XII Nigeria

In Nigeria, the challenge of proving causation in corporate climate litigation largely falls on the plaintiff, who must establish a direct link between the defendant's actions and the specific harm suffered, utilising credible scientific evidence. This evidentiary burden mirrors the difficulties faced in oil-related environmental cases, where the uncertainty of science and the high costs associated with obtaining expert evidence present significant obstacles. Cases such as Shell v Otoko highlight the courts' scepticism towards evidence that does not conclusively demonstrate causation, emphasising the necessity for litigants to present expert testimonies grounded in thorough scientific analysis and relevant to the specific scientific issues at hand, as illustrated by the Ogiale v Shell case.

The doctrine of res ipsa loquitur offers a potential avenue for overcoming these evidentiary challenges by shifting the burden of proof to the defendant. However, its effectiveness is limited, as defendants can counteract this presumption of negligence by presenting their own expert evidence of adherence to industry standards and reasonable care in their operations.

XIII Norway

In Norway, climate change litigation utilises a range of evidence, including IPCC reports and expert submissions, to establish the factual basis of claims. The Norwegian Dispute Act allows for both written and oral evidence, with the courts having significant discretion in evaluating this evidence. Notably, expert submissions provided by international associations (i.e., Environmental Law Alliance Worldwide, the Allard K. Lowenstein International Human Rights Clinic, and the Center for International Environmental Law) have been crucial in cases like People v Arctic Oil, where they supported claims about the causal link between oil extraction, production, and climate change. However, establishing a "direct" link between specific adverse effects of climate change and the actions of corporations remains a challenge. Claimants have not provided evidence of such "direct" link, and courts have yet to exercise their right to request additional evidence actively.

XIV Philippines

In corporate climate litigation in the Philippines, causation is defined as the natural and continuous sequence, unbroken by any efficient intervening cause, which produces the injury, and without which the result would not have occurred. This "proximate cause" necessitates a direct link between the defendant's actions and the injury, which, particularly in climate change litigation, is challenging due to the global and multifaceted nature of the issue. Despite these challenges, the court in the Segovia case recognised the difficulty of establishing such a direct causal link and suggested a "reasonable connection" test as a more feasible approach to establish liability in climate change litigation. This approach, along with the recognition of scientific evidence and the acceptance of various evidence types, indicates a willingness to adapt legal standards to the complexities of attributing climate change-related harms. This adaptation includes exploring alternatives like the "sufficient links" test and considering the contributions of scientific advancements in attribution science, as recommended by the Commission on Human Rights' Report, to assess causation more effectively in the context of environmental harm and climate change.

The burden of proving allegations in environmental cases, including those related to climate change, traditionally rests with the plaintiff. This includes demonstrating the causation between the defendant's actions and the environmental harm or climate change impacts. However, the Rules of Procedure for Environmental Cases (RPEC) introduce a more accommodating evidentiary framework, incorporating the precautionary principle to ease the plaintiff's burden of proof in situations where scientific certainty is lacking. This principle acknowledges the challenges inherent in establishing a direct causal link in environmental litigation and opts for a precautionary approach to protect public health and the environment. Pursuant to this principle, the court, in the 1992 NPC Case, gave credence to the testimonial evidence of the expert witness from the state weather agency which were corroborated by the testimonies of local residents. Moreover, the application of the doctrine of res ipsa loquitur in environmental cases, where negligence is inferred from the mere occurrence of an event, demonstrates the courts' willingness to infer causation under certain conditions (e.g., Sanggacala case).

Evidence in climate litigation often comprises scientific reports, such as IPCC reports, environmental impact assessments, corporate sustainability documents, and expert testimony. The courts in the Philippines have historically been liberal in accepting various types of evidence and their probative value, reflecting an understanding of the unique nature of environmental cases. Notable examples include reliance on expert submissions, government issuances, company records, and even newspaper reports to establish early knowledge of environmental risks or negligence on the part of defendants.

XV Poland

In Poland, plaintiffs bear the burden of proof in civil liability cases, including corporate climate litigation, requiring proof of damage and causation between this damage and the defendant's actions. In certain instances, the Polish Civil Code presumes unlawfulness and enforces "strict liability", removing the necessity for plaintiffs to prove negligence or fault. This is particularly relevant in environmental harm cases, where Article 435 applies strict liability, simplifying the process for the plaintiff by not requiring them to demonstrate negligence or fault on the part of the defendant. Despite the absence of a formal reverse burden of proof in environmental cases, Polish courts recognise prima facie and indirect evidence, especially in complex cases involving pollution and health impacts. The Environmental Protection Law Act aids plaintiffs by allowing courts to compel defendants to provide necessary information for assessing environmental damage claims. Courts rely on expert opinions and scientific research to understand the connections between corporate actions and climate impacts. In notable cases like ClientEarth v. PGE, the courts have acknowledged the reality of the climate crisis and the collective responsibility towards environmental protection. Notwithstanding this recognition, courts maintain a cautious approach to attribution science. Therefore, presenting a compelling case will likely require leveraging expert opinions and scientific research to clearly articulate the links between corporate actions and climate impacts.

XVI United Kingdom

In the UK, tort law's "but for" causation test is supplemented by alternative approaches for complex cases, such as those related to asbestos, allowing for liability based on cumulative causation or contribution to risk. These tests permit holding a defendant liable if their actions have materially contributed to or increased the risk of the claimant's harm, bypassing the strict application of the "but for" criterion. The adaptation of these methods to climate litigation is debated, with arguments for both.

Climate litigation evidence often includes IPCC reports and Climate Change Committee (CCC) assessments, although their sufficiency has been questioned. The ClientEarth v. Shell case highlighted the court's demand for independent expert evidence to substantiate claims against corporate actions in the context of climate change, marking a significant requirement for robust expert testimony in climate litigation in the UK.

XVII United States

In the United States, causation in tort law traditionally follows the "but for" test, necessitating proof that harm would not have occurred without the defendant's actions. Massachusetts v. EPA is a pivotal case where the Supreme Court acknowledged the causal link between greenhouse gas emissions and global warming, establishing a precedent for recognising environmental harm and the contributory role of U.S. emissions. This case, along with the increased use of climate attribution science, as seen in studies like Richard Heede's, marks a significant shift towards establishing factual responsibility for climate change-related harms in litigation. However, the challenge remains in translating this factual responsibility into legal responsibility. The San Francisco Bay cases and the Re Hawai'i Electric Company case illustrate the evolving role of climate science in the courts, indicating a growing emphasis on climate attribution studies to potentially hold entities legally accountable for climate change impacts.