LOS ANGELES, Jan. 4 (UPI) -- A federal judge in Los Angeles has imposed the most rigid set of limits ever on the U.S. Navy's use of mid-frequency sonar off the coast of Southern California.

LOS ANGELES, Aug. 7 (UPI) -- A federal judge in Los Angeles has issued a preliminary injunction to prevent the U.S. Navy from using high-powered sonar in Southern California.

WASHINGTON, Oct. 20 (UPI) -- A lawsuit filed against the U.S. Navy seeks to limit sonar systems the fleet uses to track submarines because it the technique marine life.

LOS ANGELES, Nov. 1 (UPI) -- The environmental debate over the effect that the Navy's most sophisticated sonar has on noise-sensitive whales surfaced again this week in the form of a court order temporarily blocking the use of the system virtually worldwide.

SAN FRANCISCO, Aug. 8 (UPI) -- A coalition of environmental groups is suing the U.S. Navy and the National Marine Fisheries Service in U.S. District Court, charging the Navy has no legal right to deploy a very noisy underwater sonar system that endangers marine mammals.