The Supreme Court on Wednesday lifted restrictions on the Navy's use of sonar in training exercises off the California coast, a defeat for environmental groups who say the sonar can harm whales.
The court, in its first decision of the term, voted 5-4 that the Navy needs to conduct realistic training exercises to respond to potential threats by enemy submarines.
Environmental groups had persuaded lower federal courts in California to impose restrictions on sonar use in submarine-hunting exercises to protect whales and other marine mammals.
The Bush administration argued that there is little evidence of harm to marine life in more than 40 years of exercises off the California coast.
The court did not deal with the merits of the claims put forward by the environmental groups.
It said, rather, that federal courts abused their discretion by ordering the Navy to limit sonar use in some cases and to turn it off altogether in others.