Climate change is an urgent environmental problem yet many governments have struggled to develop an effective national regulatory response. Instead, environmental advocates have turned increasingly to courts for a solution, mounting ambitious climate change cases in countries such as Australia and the United States, as well as under international law. This article examines several cross-cutting issues that present challenges for potential litigants across the broad spectrum of climate change litigation. They include problems of proof, of dealing with cumulative and indirect impacts, and of establishing a significant contribution to global warming, as well as issues surrounding the respective roles of courts and legislatures in developing a regulatory response to the problem of climate change.