The prospect of solar geoengineering, or methods of reducing incoming solar radiation in order to offset the effects of climate change, raises a number of significant governance challenges that are likely to be far more difficult to overcome than the technical barriers to development. A system of liability and compensation would need to be based on sovereign states since even if private actors undertook geoengineering, national governments would likely be held ultimately accountable for their actions. Fortunately, the international community has considerable experience of crafting and executing liability regimes, and legal scholars have developed an impressive body of knowledge about the theory and practice of international liability. When considering liability in the context of solar geoengineering, an especially problematic issue has to do with the difficulty of demonstrating causal attribution. Traditionally, proving legal liability has required showing a direct cause-effect relationship between an action committed by an alleged wrongdoer, and damages suffered by the victim.