In Indonesia, forest fires inside plantation concession areas often become highly-charged and politically-contested events. In the aftermath of major fires, the Ministry of Environment and Forestry typically commissions expert witnesses to collect the evidence needed to bring companies to court and hold them accountable. Companies also assemble their own expert teams to counter the government's allegations. Expert witnesses’ expertise, views, and practices are essential in informing court decisions; however, the work of these expert witnesses is under-researched. Drawing on theories of knowledge politics, this study finds that expert witnesses arrange and interpret scientific evidence—sometimes even contradicting widely accepted scientific understandings—to advance their client's interests. Pro-industry experts have swayed key judicial proceedings, effectively legitimising the commercial plantations sector's problematic land and fire management practices and minimising the industry's accountability for their significant socio-ecological impacts.