The Navy uses a vast area of the West Coast for training activities including anti-submarine warfare exercises involving tracking aircraft and sonar; surface-to-air gunnery and missile exercises; air-to-surface bombing exercises; sink exercises; and extensive testing for several new weapons systems.

In late 2010, the National Marine Fisheries Service gave the Navy a permit for five years of expanded naval activity that will harm or “take” marine mammals and other sealife. The permit allows the Navy to conduct increased training exercises that can harm marine mammals and disrupt their migration, nursing, breeding, or feeding, primarily as a result of harassment through exposure to the use of sonar.

Earthjustice sued the National Marine Fisheries Service to challenge the permit and the district court blocked its implementation. NMFS appealed but then dropped the appeal and agreed to issue a new biological opinion.