2. Procedures and Evidence

5. PROCEDURES RELATED TO CAUSATION

The 17 case-study countries offer contrasting and complementary procedures in handling evidence and determining causation in climate-related cases, particularly regarding the burden of proof and the standard of proof.

Burden of Proof

Across the 17 jurisdictions, the general principle is that the party asserting a fact bears the burden of proof. However, as an exception, China recognises a reversal of the burden of proof. Article 1230 of China's Civil Code and Article 8 of its newly-issued Several Provisions of the Supreme People's Court on Evidence in Civil Litigation for Ecological and Environmental Infringement allow for a reverse burden of proof in environmental pollution or damage cases, placing the onus on defendants to prove their actions did not cause harm. Specifically, defendants should prove that the pollutants discharged and the ecological impacts produced did not reach the place where the damage occurred or the action was imposed after damage and without aggravation to damage, or other scenarios made the action impossible to cause the damage.

While some jurisdictions have not explicitly embraced the reverse burden of proof, they have shown some openness to presumptions, strict liability and prima facie evidence, which remove the necessity for plaintiffs to prove negligence or fault, effectively shifting the burden of proof to the defendants:

• 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.

• In Germany, some authors advocate for shifting the burden of proof to the defendant in accordance with Section 6(1) of the UmweltHG (Environmental Liability Act), which establishes a presumption of causality unfavourable to the plant operator if the plant was essentially capable of causing the damage that occurred.[4].

Moreover, rules of evidence can be relaxed in some jurisdictions, which can aid plaintiffs to easily shift the burden to the defendants.

• In China, some presumptions are made to favour the parties representing "societal public interest" or victims with less funding and expertise. Article 16 of the Interpretation of the Supreme People's Court on Several Issues Concerning the Application of Law in Environmental Civil Public Interest Litigation  obliges the Court not to confirm admittance from plaintiffs on facts and evidence unfavourable for them when such admittance would harm the public interest.

• The Philippine 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).

• Similarly, in non-compensatory actions in Italy, such as those aimed at preventing future harm (e.g., Veronesi, Cremonini, ENI, Pasubio cases governed by mediation procedures), the stringent requirement for direct proof of causation is relaxed. This adjustment broadens the scope for claimants to argue for preventive measures based on broader scientific evidence and consensus.

• In Canada, a trier of fact may infer causation in the absence of conclusive scientific evidence by drawing inferences [5] from available facts (Snell v. Farrell; Benhaim v St‑Germain). For corporate climate litigation, this approach may be useful where it is impossible to attribute the conduct of any one corporation as contributing to climate change or to the harm suffered by the claimant.

Standard of Proof

The standard of proof for causation in corporate climate litigation varies, ranging from requiring proof beyond a reasonable doubt to a high level of probability.

• 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.

• In Germany, the relevant standard of proof in civil matters, which also applies to the element of causation, is laid down in Sec. 286 of the German Code of Civil Procedure (Zivilprozessordnung, ZPO). The court must be "freely convinced" of the relevant facts and base its conviction on a proper assessment of the evidence.[6] According to the German Federal Court of Justice, this does not require a conviction free of all doubts but rather a degree of certainty that can be actually reached in practical life, which "silences doubts without excluding them completely."[7] This could mean that causation must be proven beyond reasonable doubt.[8]

• In Kenya, the standard of proof required to be discharged in civil cases is on a balance of probability whereas criminal cases must be proved beyond reasonable doubt.

• Australia also accepts proof based on the balance of probabilities. Plaintiffs must establish legal causation, which requires balancing the scope of liability and considering the foreseeability of the harm at issue. A defendant will not be liable for a plaintiff's harm if that harm is considered too remote. To determine remoteness, courts assess whether the harm is so unrelated to the defendant's conduct that it would not fairly constitute liability.

Other procedures assist litigants in managing the burden of proof and aid courts in determining causation.

• The principles of party autonomy and judicial passiveness in Germany and the Netherlands dictate that the litigating parties primarily determine the evidence presented, including the 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. Moreover, 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.

• According to the Civil Code of China, social organisations initiating public interest litigation may receive support in discharging its burden of proof, including assistance in investigation and evidence collection from prosecuting organs, departments responsible for supervision and management of environmental protection and other institutions, social organisations, and enterprises. Additionally, for specific issues that the plaintiff should bear the burden of proof and are necessary to safeguard the public interest, the People's Court may appoint qualified appraisers to conduct appraisals.

• Poland's Environmental Protection Law Act aids plaintiffs by allowing courts to compel defendants to provide necessary information for assessing environmental damage claims.

[4] See on this Pöttker, Klimahaftungsrecht, 2014, pp. 164 ff.
[5] On inference causation in Canadian law, see R Brown, 'The possibility of "inference causation": inferring cause-in-fact and the nature of legal fact-finding', (2010) 55 R.D. McGill 1.
[6] See e.g. M Schweizer, "Standard of Proof as Decision Threshold", in L Tichý (ed.), Standard of proof in Europe, Tübingen, Mohr Siebeck, Veröffentlichungen zum Verfahrensrecht 158, 2019, pp. 4041.
[7] German Federal Court of Justice, judgment of 17.02.1970 - III ZR 139/67, BGHZ 53, 245, 256.
[8] However, it is widely discussed in the German doctrine whether this standard applies to all matters. It rather seems that German judges allow for several exceptions to this high standard, especially when the proof is difficult, for instance, in medical liability. It is then quite unsure whether this high standard will apply to climate litigation. See e.g. M Schweizer above, or H-J Ahrens, "Fact Finding under German Law of Civil Procedure", in L Tichý (ed.), Standard of proof in Europe, op.cit., pp. 9899; C Althammer and M Tolani, "Proof of Causation in German Tort Law", in L. Tichý (ed.), Standard of proof in Europe, ibidem, p. 114..