1. Introduction
As the impacts of anthropogenic climate change have become more apparent, the range and types of claims that have been brought to courts for adjudication around the world have become more varied. Recent cases range from class and representative actions brought by native title holders against government for failures to address the risks of climate change,[1] to local authorities seeking compensation for the additional costs associated with climate mitigation,[2] to individual disputes relating to land valuation.[3] The varied and expanding nature of climate cases are testing the boundaries of the rules of evidence across a range of dimensions, from understanding what evidence is relevant to a particular dispute, to the regulation of expert evidence, to conceptions of what types of witnesses hold the relevant knowledge and expertise to be able to speak about the impacts of climate change. This chapter reflects on how climate litigation raises questions about the presumptions underpinning trial practice and evidentiary principles, as well as the adaptability of existing evidentiary rules in cases raising novel claims about responsibility and liability for the negative impacts of a changing climate.
Just as the boundaries of substantive law, and evidence law more generally, are being tested in climate litigation, cases in Australia are testing the Uniform Evidence Law’s (‘UEL’) claim to facilitate the admission of relevant evidence.[4] This is because ‘relevant’ evidence must speak to the ‘facts in issue’ in the case, meaning facts over which the parties disagree, or which one party is expected to prove to the court.[5] In climate litigation across Australia, the facts in issue vary widely, encompassing administrative law and civil enforcement, matters of tort, consumer protection and climate risk disclosures, human rights claims and even criminal prosecutions.[6] As such, what is ultimately considered ‘relevant’ to a particular dispute can also vary widely. Different cases will circumscribe the boundaries of a dispute in different ways, but an overall trend we have observed is that courts are becoming more willing to accept, or even assume, evidence supporting the impacts of climate change.
At the same time, in many cases the court will be constrained in terms of how much account it can take of those impacts within the boundaries of the particular dispute.[7] In practice this means that climate cases often recognise and incorporate discussion of a range of scientific reports and will hear evidence from traditionally qualified expert witnesses, but it will only be in certain types of cases that this evidence will end up having an actual bearing on the reasoning or outcome of the case. This evidence might be used to establish the existence of anthropogenic climate change itself, it might be attribution evidence led to establish causation for specific impacts of increased greenhouse gases or it might relate to flood risks in quotidian land valuation challenges. Where courts have accepted expert evidence in relation to the potential relevance or impacts of climate change,[8] the focus has tended to be on formal questions of whether risks have been considered adequately. However, in a small number of cases, additional evidential issues have also arisen, including questions concerning when expert evidence will be needed, how that expert evidence is to be assessed and who can be recognised as an expert.
In Australian climate cases, the inclusion of First Nations custodians as experts in relation to the effects of climate change on their traditional lands poses new challenges for the law of evidence. This is notwithstanding the inclusion within the UEL of specific sections designed to facilitate the admission of evidence from Aboriginal and Torres Strait Islander witnesses. To the extent that traditional cultural knowledge exists outside the parameters of the types of conventional ‘science’ or forms of expertise that courts have become familiar with, the legal system is having to adapt to new ways of conducting court business.
We unpack these themes in this chapter, exploring how climate change may require new ways of thinking about the application and limits of core evidential concepts, including the rules governing relevance, expert witness evidence and the evidence of First Nations traditional owners.
- Pabai Pabai & Anor v Commonwealth of Australia (VID622/2021). ↵
- Lliuya v RWE AG Case No. 2 O 285/15 Essen Regional Court. ↵
- Croghan v Blacktown City Council [2019] NSWLEC 2. ↵
- UEL jurisdictions are those that have adopted an Evidence Act modelled on the Evidence Act 1995 (NSW/Cth). These are New South Wales, Victoria, the ACT, the Northern Territory, Tasmania, Norfolk Island and the Commonwealth. See the glossary for more detail. ↵
- Goldsmith v Sandilands [2002] 190 ALR 370 [2]. ↵
- Mark Hamilton, ‘Characterising Climate Change Litigation in Australia’ (2023) Environmental and Planning Law Journal 539. ↵
- A particularly stark example of this has occurred in a number of cases in England where defendants who have been charged with offences relating to climate protests have been prevented by the trial judge from even raising as part of their defence any mention of concern about climate change as a motivating or contextual factor. See <https://defendourjuries.org/>. ↵
- For example, in cases relating to approvals of projects that will increase the production of greenhouse gases. ↵
Uniform Evidence Law (UEL) refers to the evidentiary and procedural regime governed primarily by an Evidence Act that is based on the Model Evidence Bill drafts produced by the Australian Law Reform Commission in response to their Evidence Inquiry 1980 - 1987, rather that the common law. Jurisdictions that have adopted the UEL are New South Wales, Victoria, the ACT, the Northern Territory, Tasmania, Norfolk Island and the Commonwealth. All of these jurisdictions have adopted an Evidence Act that mirrors in most substantive respects thethe Evidence Act 1995 (NSW/Cth). Some sections of the UEL were amended or added following the 2004 – 2005 Review by the Australian Law Reform Commission, the New South Wales Law Reform Commission and the Victorian Law Reform Commission. While not all the Acts are exactly uniform in each jurisdiction, the differences are relatively minor.
Aboriginal and Torres Strait Islander peoples are the first peoples of Australia, meaning they were here for thousands of years prior to colonisation. Current research confirms that Aboriginal and Torres Strait Islander peoples have lived on the Australian continent for upwards of 60,000 years. While estimates vary, this figure represents the most widely accepted timeframe based on available evidence. Australia is made up of many different and distinct Aboriginal and Torres Strait Islander groups, each with their own culture, language, beliefs and practices. Aboriginal people come from the mainland of Australia and its surrounding islands. The Torres Strait region is located between the tip of Cape York and Papua New Guinea and is made up of over two hundred islands. First Nations is a collective term that refers to Indigenous peoples of a nation, region or place. Indigenous peoples refers to the people with historical and ancestral ties to a place that pre-date colonisation, and is the term used by the United Nations in its Declaration on the Rights of Indigenous Peoples. All these collective terms can be used respectfully. As proper nouns, all should be used with a capital letter.
