In a case that could establish a precedent on how far the military must go to protect marine mammals, the U.S. Supreme Court on Wednesday will hear arguments on the use of sonar during war games off the Southern California coast.

The Navy is appealing a Ninth Circuit Court of Appeals decision last winter that restricted sonar and banned its use in some areas to avoid harming and potentially killing whales and dolphins.

The Navy contends that sonar is a vital component of military exercises crucial to national security and says it is used in a manner that poses little threat to animals.

Whale beachings and deaths around the world have been linked to sonar use, but so far no such connections have been made in Southern California.

While the focus of the lawsuit filed by the Natural Resources Defense Council is on exercises off San Diego, Orange and Los Angeles counties, Ken Balcomb, a scientist with the Center for Whale Research in Washington state said the case may set limits for the Navy throughout the nation's coastal waters.

But the case is about more than that.

President Bush and his Council on Environmental Quality intervened in January, concluding that national security was at risk and excusing the Navy from court-ordered sonar restrictions.

The appeals court reinstated most conditions, but softened some to allow the Navy to continue exercises while it contemplated an appeal to the Supreme Court.

"When the president intervened at the Navy's request, it raised the case to another level in terms of its impact," said Joel Reynolds, an attorney for the Natural Resources Defense Council in Los Angeles. "It is no longer just an environmental case. It is about whether we have an imperial president, a president who is above the law."

The environmental group contends the Navy was obligated to study the environmental impact of 14 war exercises involving aircraft, ships and submarines between 2007 and 2009 after a preliminary assessment showed mammals would be exposed to ear-splitting sound 170,000 times during that two-year period.

"That's a very significant impact," Reynolds said. "You clearly have a situation where an environmental impact statement is required."

Not so, the Navy said in a court document. At most, it said, the exposure would result in eight dolphins suffering permanent hearing loss -- and only if sailors failed to deploy their own safety measures.

Consequently, no environmental study is required, the Navy said.

Ten exercises have taken place off the Southern California coast to date. The next is scheduled for mid-November.

Navy goes first

With the high court launching a new term Monday, observers say the case's position near the front of the line could indicate a decision will be rendered by December, rather than near the end of the court's term in June.

Reynolds said the Supreme Court hearing will be relatively short.

"Each side gets a half-hour," Reynolds said, adding that the Navy will go first. And he said there will be little time for a presentation.

"They will let you get started," Reynolds said. "But … they very quickly jump in with their questions."

Navy officials in San Diego County declined to discuss the case, referring questions to the Pentagon. A Navy spokesman in Washington offered a statement on the condition he not be named.

"This is a question of national security," the spokesman said. "Our primary mission is to maintain a trained and effective Navy. And antisubmarine warfare is the number one threat facing the Navy today."

According to Navy court documents, sonar is the only effective tool for detecting the quiet, diesel-powered submarines of hostile nations.

And local Navy officials said early this year that Southern California is one of the best places to train with sonar. They said the area's underwater canyons are the kinds of places enemy submarines try to hide.

Local military officials also maintained that it is crucial to train in shallow coastal waters, where it is difficult to distinguish the enemy's sound signature from echoing noises.

Coastal waters and underwater canyons also teem with marine mammals. With that in mind, a federal district judge in Los Angeles in January blocked the Navy from conducting exercises within 12 miles of the shore and in a canyon between Santa Catalina Island and the military-owned San Clemente Island west of San Diego.

While not pleased with the ban, the Navy focused its appeal on two court-imposed restrictions: that sailors shut down sonar when they spot whales a little more than a mile away, and turn down the volume when conditions are present that allow sound to travel long distances without losing its strength.

Reynolds said the Navy can effectively train with the restrictions.

Since 2000, sonar use has been linked to the beachings of dozens of whales reported around the world, at places such as Spain, Greece, the Bahamas, Hawaii and Washington state. And in many cases, whales died.

Balcomb, the scientist, said the powerful sound causes whales to panic and stampede to the surface. They essentially get the bends, as gas bubbles expand and rupture delicate blood vessels in their brains and ears, he said.

But the Pentagon spokesman said that since the Navy set new sonar limits in January 2007, no strandings have been triggered by U.S. sonar training anywhere in the world.

And, he said, no mammal deaths have been linked to sonar in Southern California in 40 years of use.

Contact staff writer Dave Downey at (760) 745-6611, Ext. 2623, or ddowney@nctimes.com.