Liability for causing or failing to mitigate climate change has long been proposed as an alternative, or backstop, to lagging international cooperation. Thus far, there has been very limited success in holding governments or individuals responsible for the emission of greenhouse gases (GHGs) that are considered the primary cause of anthropogenic climate change. The recent landmark decision in Urgenda Foundation v. Government of the Netherlands (Ministry of Infrastructure and the Environment) breaks with this tradition. In June 2015, the Dutch District Court (The Hague) held that the current climate policies of the government are not sufficiently ambitious for it to fulfil its duty of care towards Dutch society. The judgment, and the accompanying order for the government to adopt stricter GHG reduction policies, raises important questions about the future of climate change liability litigation, the separation of powers between the judiciary and the legislature, and the effect of litigation on international climate change negotiation and cooperation.