The federal Endangered Species Act (ESA) has long been one of the major flash points in the "property rights" debate. This report first outlines the ESA provisions most relevant to the act's impacts on private property, and then surveys the major ESA-relevant principles of Fifth Amendment takings law. The report then proceeds to its core topic: the court decisions adjudicating whether government measures based on the ESA effect a taking of property under the Fifth Amendment. The cases address four kinds of ESA measures: (1) restrictions on land uses that might adversely affect species listed as endangered or threatened; (2) reductions in water delivery or allowable diversion to preserve lake levels or instream flows needed by listed fish; (3) restrictions on the defensive measures a property owner may take to protect his/her property from listed animals; and (4) restrictions on commercial dealings in members of listed species. To date, only one of the 15 ESA-based takings cases revealed by research has found a taking, and that decision has been undermined by a later decision of the same judge.

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. Liability for harms allegedly caused by climate change has raised another crop of legal issues. The Supreme Court decision that the CAA bars federal judges from imposing their own limits on GHG emissions from power plants has led observers to ask: Can plaintiffs alleging climate change harms still seek monetary damages, and are state law claims still allowed? The one ruling so far says no to both. Questions of insurance policy coverage are also likely to be litigated. Finally, the applicability of international law principles to climate change has yet to be resolved. Water shortages thought to be induced by climate change likely will lead to litigation over the nature of water rights. Shortages have already prompted several lawsuits over whether cutbacks in water delivered from federal projects effect Fifth Amendment takings or breaches of contract. Sea level rise and extreme precipitation linked to climate change raise questions as to (1) the effect of sea level rise on the beachfront owner's property line; (2) whether public beach access easements migrate with the landward movement of beaches; (3) design and operation of federal levees; and (4) government failure to take preventive measures against climate change harms. Other adaptation responses to climate change raising legal issues, often property rights related, are beach armoring (seawalls, bulkheads, etc.), beach renourishment, and "retreat" measures. Retreat measures seek to move existing development away from areas likely to be affected by floods and sea level rise, and to discourage new development there. Natural disasters to which climate change contributes may prompt questions as to whether response actions taken in an emergency are subject to relaxed requirements and, similarly, as to the rebuilding of structures destroyed by such disasters just as they were before. Finally, immigration and refugee law appear not to cover persons forced to relocate because of climate change impacts such as drought or sea level rise.

The scientific, economic, and political questions surrounding climate change have long been with us. This report focuses instead on a relative newcomer: the legal debate. Though the first court decisions related to climate change appeared over a decade ago, such litigation has proliferated in recent years.