San Manuel contested the complaint by asserting the labor board didn't have jurisdiction because federal law recognizes Indian tribes as sovereign governments. The labor board disagreed in a 2004 opinion that, for the first time, said tribes are covered by the National Labor Relations Act that bars unfair labor practices and gives workers the right to organize and bargain with employers. In question are the bargaining rights for some 250,000 workers, most of them non-Indians, at the nation's 400-plus tribal casinos.

Tribal gambling has exploded into a $22 billion-a-year industry in the US - richer than Las Vegas - with Indian casinos now in 28 states. A few tribal casinos in California are unionized, including the San Manuel, but most workers at Indian casinos are nonunion. Unions have been trying hard to make inroads with the growing work force but say they've had trouble without the protection of the National Labor Relations Act. Even though San Manuel employees already have joined Communications Workers of America, the ruling could undercut the tribe's ability to deal with the union on the tribe's own terms, which critics say favor the tribe.

The tribe contends it treats its workers well, and employees at the San Manuel casino have praised conditions there. "We are disappointed by the ruling today," said Henry Duro on Friday, chairman of the San Manuel tribe, which was backed in the case by the National Indian Gaming Association and leading tribes. "We believe that these gaming projects help tribes to fulfill essential governmental functions by providing education, health care, housing, senior care and other key programs," Duro said. "Those are basic governmental obligations that could be impacted by this decision." A tribal spokesman said the tribe hadn't decided whether to appeal. Jack Gribbon, political director for Unite Here in California, said the ruling came down on the side of "workers who are the engine behind the extremely lucrative tribal gaming industry." If the ruling stands and tribes don't come to the table, "it creates the opportunity for a major clash, for disputes and unrest and picketing and striking," Gribbon said.

The appeals court said San Manuel read too much into the fact that the 1988 Indian Gaming Regulatory Act permits tribes and states to regulate Indian casinos. "It is a considerable leap from that bare fact to the conclusion that Congress intended federal agencies to have no role in regulating employment issues that arise in the context of tribal gaming," said the 23-page order. Also on the appeals panel were Judges Stephen F. Williams and Merrick B.