This chapter finds that the ISA defines ‘marine environment’ broadly and imposes a threshold requirement – ‘serious harm’ – to the definition of ‘marine environmental damage’ in DSM. It argues that the determination of whether the threshold has been crossed should be based on both factual assessment and value judgment. The measure of marine environmental damage in DSM is a much more complex issue. This chapter draws on experience in other contexts, including the International Oil Pollution Compensation Funds, the ‘F4’ claims before the United Nations Compensation Commission, the US and EU laws and practice and discussions in the context of the Convention on Biological Diversity. Upon examination, it proposes to rely primarily on a cost-based method, while valuation of pure environmental damage or interim loss secondary. It suggests a two-step pattern for measuring environmental damage in DSM.

This chapter examines issues related to the definition and valuation of environmental damage in areas beyond national jurisdiction (ABNJ): what general principles govern reparation for environmental damage; what types of environmental damage should give rise to compensation or other measures of reparation; and how should such compensation or other measures be assessed in monetary terms? The chapter draws out the characteristics of, and considerations relating to, the global commons areas that might affect the approach taken to these questions, and how, if at all, compensation for environmental damage has been addressed in the existing regimes governing ABNJ under consideration in this study. To inform the discussion, the chapter examines other relevant international principles and rules that have been adopted or applied to address compensation for environmental damage at the international level.