This chapter first identifies the numerous ways in which scientific knowledge may gain legal significance in environmental disputes brought before ITLOS. It then discusses the framing techniques with which ITLOS adjusts the science-intensity of its legal inquiry. In particular, deeming science-intensive disputes justiciable, crafting precautionary justifications, mandating the parties’ expert-led co-operation in scientific issues, and utilizing scientific progress for setting a high bar for states’ due diligence obligations will be discussed. As to fact-finding, the chapter discusses the variety of evidentiary powers granted to the tribunal, and shows that it primarily relies on party-adduced evidence, while leaves its novel fact-finding avenues underutilized. The chapter concludes with discussing the causal tests announced by the tribunal on the rare occasions it has laid out a causal inquiry.