DIAMOND BEACH, NJ - Before losing a two-year court fight in May, a private beach club on the Atlantic Ocean here wanted to charge $15,000 for a lifetime membership or $700 for eight badges to get on the beach this summer. But a three-judge appeals court threw out those fees, ruling that exclusive oceanfront clubs with high rates violated New Jersey's public trust doctrine.

The court opened the little 480-foot beach in Cape May County, the Atlantis Beach Club, to all members of the public for what it called "reasonable" fees. The state's environmental department set the fees last month at $55 for the season, $40 for a month, $15 for a week or $3 for a day.

The club's president and co-owner, Robert Ciampitti, is incensed at both the ruling and state-imposed fees, saying they do not cover the club's property taxes and other costs of operation, let alone provide a profit. He has appealed the ruling to the State Supreme Court and threatened to close the beach unless the state increases the fees.

Environmentalists and other advocates of "open beaches" in New Jersey, however, are elated. They say the ruling, if left undisturbed by the State Supreme Court, will provide a powerful legal tool for future court fights against exorbitant charges by beach clubs and private beach owners who try to keep the public from the ocean waters and sand in front of their dunes and homes.

"The coast is becoming increasingly privatized," said Tim Dillingham, executive director of the American Littoral Society, an environmental organization, which joined the court fight against the club that a group of Atlantis's neighbors started in 2002. "We are seeing a race along the New Jersey coast to lock up access to the beaches and privatize great lengths of it."

In 1977, a state survey found that about 26 percent of the Atlantic coastline in New Jersey was privately owned. The state's Department of Environmental Protection says it does not have a more recent breakdown of public-private ownership. But "open-beach" groups and environmental organizations said they thought the share of private ownership and restrictions on beach access for the public has increased in recent years as bigger homes and condominiums filled lots off beaches or replaced the hotels, clubs and bungalows of earlier generations.

"With these very expensive houses, people have a sense of entitlement to exclusivity," Mr. Dillingham said.

The court's decision in May is the first major one in 20 years in New Jersey dealing with the public trust doctrine, a concept created centuries ago in Roman law that opened the ocean and tidal land to all for fishing and navigation.

In 1984, the New Jersey Supreme Court expanded the doctrine on the state's 126-mile Atlantic shoreline, saying swimmers, boaters, fishermen and others were entitled to access to the ocean's waters and tidally washed beaches, whether publicly or privately owned. It also said they were entitled to use "some" part of the dry sand on private beaches to sunbathe, rest or relax.

The appeals court ruling in May went further, saying the public was entitled to use all the dry sand at Atlantis. It also dismissed Atlantis's proposed fees as exclusionary and said they discriminated against individuals and small families, and it derided the owner's notion he was entitled to make a profit from his property on the Atlantic.

An assistant state attorney general, Stephen Brower, said his office planned to use the Atlantis ruling as additional legal precedent in a current court fight against a beachfront homeowners group in Point Pleasant Beach. The state has accused it of barring the public from the dry sand on its beaches.

In addition, he said, the state has started investigating complaints that developers of new oceanfront homes in Sea Bright and Monmouth Beach have tried to restrict beach access.

Perhaps the nastiest and longest-running beach-access fight on the coast has helped to block a $50 million project by the Army Corps of Engineers on Long Beach Island, a popular tourist haven in Ocean County. The plan was to rebuild all 16 miles of beaches on the island by pumping sand to them from offshore. The corps requires public access and use of both dry and wet sand on beaches that are rebuilt with federal money.

Some towns on the island offer plenty of access. But in the communities of North Beach and Loveladies, signs by driveways leading to grand beach homes say the beaches are private, and access is barred.

State officials say they are negotiating with homeowners for guarantees allowing public use of private beaches and perpendicular access from the roads every quarter mile. They say they hope to finish that work by fall.

The project has also been delayed by the federal government's failure to provide its full 65 percent share of the beach-rebuilding project. State officials say they hope some federal money will be available soon, so pumping can start before winter.

Some officials on Long Beach Island say some of its beaches are seriously eroded now and will remain vulnerable to coastal storms until they are rebuilt.

Atlantis's neighbors say they started the court fight two years ago because of excessive fees and the club's refusal to allow them to use its entry boardwalk to reach a neighboring, less costly beach in front of a condominium complex, Seapoint Village. After a protest march in 2002 and the arrest of one opponent for trespassing, the neighbors banded together as the Raleigh Avenue Beach Association sued Atlantis, charging it had violated the public trust doctrine.

The group is pleased with its court victory. "The public trust doctrine was not something that we just made up," said a spokeswoman, Carmen Axmann. "It was there when Atlantis acquired the property, is still there, and, for the public's sake, will be around in the future."

The group's lawyer, Stuart Lieberman, noted, "With all the development pressure in coastal New Jersey, this is an increasingly significant issue."

Mr. Ciampitti's lawyer, Gerald J. Corcoran, has asked the state Supreme Court to review the ruling. He said, "I don't believe the public trust doctrine requires private property owners to make a privately-owned beach totally available to the public and blocks charging fees negotiated between a club owner and members."

In an interview, Mr. Ciampitti said he thought the decision improperly took private property without compensation. Heargued that the United States was "premised on being able to make a profit."

But in the unanimous decision, the court said, "The notion that lands are to be held in public trust, protected and regulated for the common use and benefit, is incompatible with the concept of profit."

Despite their court victory, some members of the Raleigh group who once went to Atlantis's beach say they will not return because of what they called past excessive charges, curt guards and sour relations. Instead, they said, they'll go to free municipal beaches nearby or the beach at the Seapoint condominium next to Atlantis.

"It's the principle of the thing," said one, Ed Shirk.

Chuck Slugg said he saw fees to get on the beach rise to $700 a year from $300 by the end of a five-year agreement.

"We will not give them any more money," his wife, Mary Jane Slugg, said of Atlantis.