Winter V. Natural Resources Defense Council - Background and Procedural History

Background and Procedural History

The Navy scheduled 14 training exercises through January 2009 off the coast of southern California. These exercises involve the use of “mid-frequency active sonar” to detect enemy submarines. Environmentalists claim that the high decibel levels used harm whales, causing beach strandings. In February 2007, however, the Navy issued an environmental impact assessment under the National Environmental Policy Act (NEPA), concluding that the use of mid-frequency active sonar during the exercises would cause minimal harm to marine mammals.

Petitioners, mostly environmental groups, sought declaratory and injunctive relief against the exercises, on the ground that they violated NEPA, plus other environmental laws not material to the Supreme Court decision. The district court granted a preliminary injunction barring conduct of the exercises. On remand from the Court of Appeals for the Ninth Circuit, the district court modified the preliminary injunction to allow the Navy to use the sonar if it used mitigation measures. On the Navy’s second appeal, challenging two of the mitigation measures, the Ninth Circuit affirmed the modified injunction, noting that plaintiffs (petitioners in the Supreme Court) had carried their burden of showing a “possibility” of irreparable injury and that the balance of hardships weighed in favor of plaintiffs.