This report surveys existing law for legal issues that have arisen, or may arise in the future, on account of climate change and government responses thereto. At the threshold of many climate-change-related lawsuits are two barriers—whether the plaintiff has standing to sue and whether the claim being made presents a political question. Both barriers have forced courts to apply amorphous standards in a new and complex context. Efforts to mitigate climate change—that is, reduce greenhouse gas (GHG) emissions—have spawned a host of legal issues. The Supreme Court resolved a big one in 2007—the Clean Air Act (CAA), it said, does authorize EPA to regulate GHG emissions. Quite recently, a host of issues raised by EPA’s efforts to carry out that authority were resolved in the agency’s favor by the D.C. Circuit. Another issue is whether EPA’s “endangerment finding” for GHG emissions from new motor vehicles will compel EPA to move against GHG emissions under other CAA authorities. Still other mitigation issues are (1) the role of the Endangered Species Act in addressing climate change; (2) how climate change must be considered under the National Environmental Policy Act; (3) liability and other questions raised by carbon capture and sequestration; (4) constitutional constraints on land use regulation and state actions against climate change; and (5) whether the public trust doctrine applies to the atmosphere.