WASHINGTON, Aug. 9 — The Bush administration is arguing that a major environmental law does not apply to the vast majority of oceans under United States control, a move that environmentalists say could allow military maneuvers, oil and gas pipelines, commercial fishing, ocean dumping and scores of other activities to escape public environmental review.

In a federal court case in Los Angeles that involves the testing of a new type of sonar system by the Navy, the Justice Department said that the National Environmental Policy Act of 1969 — landmark legislation that requires federal agencies to review the environmental implications of their projects — did not apply beyond the nation's territorial waters, which traditionally extend three miles from shore.

That view is being challenged by the Natural Resources Defense Council, which asserts that in addition to the territorial waters, the act covers all activity within the nation's "exclusive economic zone," which extends 200 miles from shore.

A decision in the case is expected later in the summer.

Environmentalists say that barring application of the act in these zones would open up the oceans to unregulated activity that could damage them and destroy marine life.

In addition to the sonar project, which they say could disorient and kill whales and dolphins, they say other unregulated activity would include commercial fishing for depleted species, proposals for liquified natural gas plants and pipelines, and other energy projects.

Offshore oil and gas drilling would not be affected by the administration's position because another law, the Outer Continental Shelf Lands Act, specifically requires that the environmental law apply to such activity.

At issue is the National Environmental Policy Act, often referred to as the Magna Carta of environmental law. Signed by President Richard M. Nixon on Jan. 1, 1970, the act requires all federal governmental actions to be reviewed and analyzed for their effect on the environment.

In an indication of the importance of the matter, the White House Council on Environmental Quality convened with ranking officials from five agencies and departments to discuss the implications of the Justice Department's position both before the department filed its brief and then again this week, administration officials said. They plan to discuss it further in September.

Administration officials said there was little disagreement at the meeting, which was first reported today by The Times-Picayune of New Orleans, about the administration's approach. And the Justice Department has argued in the sonar case that federal agencies should decide case by case whether to apply the National Environmental Policy Act in the oceans.

But e-mail messages written before the meeting suggested that officials from the National Oceanic and Atmospheric Administration disagreed with the Navy.

One message written by a Navy official hailed the "good news" that the Justice Department agreed with the Navy, "over NOAA objection," that the environmental law "does NOT extend beyond the limits of our territorial waters."

Administration officials said that the Justice Department position and the meeting did not represent a change of policy, but environmentalists disagreed.

"This is a major policy change," said Andrew Wetzler, a lawyer with the Natural Resources Defense Council in Los Angeles. "For the first time, the White House is considering stepping in and seeking to impose the Navy's restrictive view of the statute on the entire federal government."

The Navy has long believed that the act does not extend to activities conducted within the nation's "exclusive economic zone," which stretches 200 miles off all coastal waters and thus covers more than one million square miles off all American coasts, including those of Alaska and Hawaii. The Navy appears to be the driving force behind the Bush administration's discussion of whether to apply that concept to all federal activity in the zone.

Administration officials believe that the environmental act is too restrictive, that it spawns nettlesome lawsuits and that most ocean activity is already regulated by an executive order signed in 1979 by President Jimmy Carter, according to administration officials and internal e-mail correspondence that was obtained by environmental groups opposing the administration's view.

Environmental groups assert that the Carter executive order is too weak to guarantee enforcement. They say it does not provide for lawsuits or public review, meaning that an array of damaging activities could take place far out at sea without public knowledge or recourse.

Michael Jasny, a senior policy analyst at the Natural Resources Defense Council in Los Angeles, said that the National Environmental Policy Act "depends on public comment and public scrutiny and judicial review for its effectiveness, and if you do away with it, all of that would be lost — we'd have no public accountability" about military and industrial activities in the oceans.

Tim Eichenberg, a lawyer with Oceana, a group in San Francisco dedicated to preserving the oceans, called the executive order "a very poor cousin" to the policy act.

"The executive order doesn't provide for public input or any analysis of alternatives and it doesn't allow for judicial review — there is no recourse for the public," he argued.

Administration officials said that their position in the California case did not represent a change of policy. They said that the National Environmental Policy Act, signed into law before the United States established its exclusive economic zones, was never intended to apply to the ocean beyond the territorial waters and did not apply now.

But an internal Navy document contradicts that view, noting that the Justice Department and the Council on Environmental Quality in the Clinton administration "pressed to apply N.E.P.A. worldwide."