This chapter debates the consistency of the deployment of Solar Radiation Management (SRM) with international law. SRM might help to counter global warming at relatively low cost, but it could also have substantial negative environmental impacts. Jesse Reynolds, reviewing all the relevant international treaties, as well as customary international law, argues that solar geoengineering could be consistent with international law. There is even some evidence, he argues, that solar geoengineering may be required by international law. Kerryn Brent reaches the exact opposite conclusion. She argues that solar geoengineering at scale would violate the no-harm rule and is prohibited by the UNFCCC and other treaties.