Science in the courtroom: evidentiary needs in climate litigation

Grantham Climate Litigation Guide 1

This guide, the first in a new series from the Grantham Research Institute at LSE and the Grantham Institute at Imperial College London, explores and reflects on the role of scientific research in climate litigation. It outlines the main types of evidence used across three major case categories and how scientific evidence is utilised by claimants. The guide focuses on strategic climate litigation cases that aim to further climate action, drawing on a range of case studies from around the world:

• Part 1 outlines how science is understood and perceived in climate litigation. It reviews how courts have evaluated and engaged with scientific evidence, reflecting on the different roles played by scientists in the courtroom and the importance of the Intergovernmental Panel on Climate Change (IPCC).
• Part 2 distinguishes between the different evidentiary needs present in the three different types of cases. It provides practitioners, non-specialists and those generally interested in the science–law intersection with a clear overview of how different types of scientific evidence have historically been used across climate litigation.

Summary points

• Climate litigation has emerged as an influential area of climate governance. Scientific evidence plays a key role in helping courts adjudicate cases about government and corporate responsibility for addressing climate change.
• Scientific evidence is used differently across case strategies. This guide focuses on government framework cases (which contest governmental climate policy), corporate framework cases (which challenge companies’ climate-related performance), and polluter pays cases (which seek damages for climate-related harm).
• Climate science is evolving rapidly, providing an expanding evidentiary basis for climate litigation. However, there is limited systematic analysis of the evidentiary needs of different climate litigation strategies.
• Courts tend to favour evidence from the IPCC over standalone studies, creating a de facto evidentiary hierarchy.
• Scientists can influence litigation both on behalf of parties but also independently of legal teams. They can act not only as expert witnesses but also as advisors, independent researchers, contributors to amicus curiae briefs that provide expert knowledge, and facilitators in judicial education.
• Evidentiary discussions vary across case strategies:
  • Government framework cases centre on aligning national targets and actions with global temperature goals, carbon budgets and ‘fair share’ principles, assessing compliance with targets, and demonstrating the impacts of climate change.
  • Corporate framework cases often seek company-level emissions reductions in line with global or sectoral emissions pathways, analysing transition plans and corporate target setting.
  • Polluter pays cases rely on attribution science to establish a causal chain between large emitters and harm to plaintiffs.
• Tensions between what is regarded as ‘best available science’ and what is regarded as persuasive by legal audiences create a need for effective scientific communication within legal narratives.

DOI: 10.21953/researchonline.lse.ac.uk.00137472

About the Grantham Climate Litigation Guides

These guides are a collaboration between the Grantham Research Institute at LSE and the Grantham Institute at Imperial College London. The series is designed to provide informed guidance on the use of climate science and evidence in legal and policy contexts in concise, non-technical language. Further guides will be published in 2026.