High on a hilltop overlooking miles of vineyards and the sparkling Russian River, two circus-like tents front a parking lot carved from the steep slope.

Inside, 269 slot machines clang and chime around the clock, the background music of the River Rock Casino -- a popular destination for northern California seniors that happens to be in violation of the local agricultural zoning code.

The Dry Creek Rancheria Band of Pomo Indians refused to halt construction of the casino despite allegations of building, safety and environmental violations. And even the state's top law enforcement official couldn't stop it from opening last fall.

"The tribe just said 'Stuff it -- stuff it, governor, stuff it, attorney general,"' said Alexander Valley Association President Karen Passalacqua, who has led local opposition.

Attorney General Bill Lockyer and Gov. Gray Davis were thwarted by tribal sovereignty, a wall of legal independence that has become familiar to state and local officials across the nation.

Tribal sovereignty is rooted in the principle that Indian tribes were sovereign nations assimilated by the United States. Tribes' independence from most state oversight was established by the U.S. Supreme Court 170 years ago, and many tribes have treaties with the government recognizing special status and guaranteeing special rights.

But sovereignty began receiving new attention with the spread of casinos after Congress approved the National Indian Gaming Act in 1988.

"It exploded these sovereignty issues nationwide, and it exploded them in ways that people had never even thought of," said Guy Martin, whose Washington, D.C., law firm represents communities in tribal disputes in about 20 states. "We're coming upon a time when we could be forced to reconsider the entire issue of Indian sovereignty."

A trio of Supreme Court decisions, two of them last year, narrowed tribes' ability to restrict intrusion by states on law enforcement and tax issues.

"Indian Country recognized the U.S. Supreme Court was really on a rampage against tribal sovereignty," said Tracy Labin, an attorney with the Native American Rights Fund. "Certainly tribal gaming is something that catches everyone's attention, but very quietly the U.S. Supreme Court is just chipping away."

Tribes have responded with a coordinated effort to fight for their rights in court. They're also proposing national legislation to protect their sovereignty, a proposal opponents say would give tribes rights they've never had.

"The biggest sovereignty contest is between tribes and states, because the tribes are trying to set themselves up as equal to states," Martin said.