The system of investor-state dispute settlement (ISDS) found in over 3,000 bilateral investment treaties and numerous regional trade agreements has been criticized for interfering with the rights of sovereign states to regulate investment in the public interest, for example, to protect the environment and public health. This article argues that while much of the public debate around ISDS has focused on a small number of cases that have arisen over the regulation of tobacco packaging, there is a far greater threat posed by the potential use of ISDS by the fossil fuel industry to stall action on climate change. It is hypothesized that fossil fuel corporations will emulate a tactic employed by the tobacco industry-that of using ISDS to induce cross-border regulatory chill: The delay in policy uptake in jurisdictions outside the jurisdiction in which the ISDS claim is brought. Importantly, fossil fuel corporations do not have to win any ISDS cases for this strategy to be effective; they only have to be willing to launch them. The article concludes with three options to reform trade and investment agreements to better align them with climate change mitigation efforts: (i) exclude ISDS provisions; (ii) prohibit fossil fuel industries from accessing ISDS; or (iii) carve out all government measures taken in pursuit of international obligations (for example, under the Paris Agreement on climate change) from challenge under ISDS.