PORTLAND - After more than a decade of legal battles over assisted suicide, a Supreme Court ruling that affirmed states have the authority to regulate medical treatment of the terminally ill may help turn a landmark Oregon law into a national model.

The 6-3 ruling Tuesday was considered a rebuke to the Bush administration and former Attorney General John Ashcroft, who the court said improperly threatened to use a federal drug law against Oregon doctors who prescribe lethal doses of medicine to dying patients who request it.

“The favorable ruling by the Supreme Court now permits other states to move forward in replicating Oregon's landmark law,” said Peg Sandeen, executive director of the Death with Dignity National Center.

At least six other states have proposed or are considering some form of an assisted suicide law, with bills currently in the legislatures of California and Vermont.

But the ruling was harshly criticized by longtime opponents, including the leader of the Roman Catholic Church in Oregon.

“The failure of our governmental structures to prevent doctors from violating medicine's historic ethical prohibition, ‘Do no harm,' is a tragic error of immense proportion and significance,” said Archbishop John Vlazny, head of the Archdiocese of Portland.

But some cancer specialists disagreed.

“I think Oregon physicians have, by and large, been comfortable with how it serves their patients,” Dr. Peter Rasmussen said of the Oregon law. “I think the biggest impact is going to be outside of Oregon.”

The law was passed by initiative in 1994 and affirmed by even larger majority of Oregon voters in 1997, within weeks of another Supreme Court ruling in a Washington state case that also backed states as the final authority for regulating medical practice.

Oregon health officials have tracked usage of the law since it went into effect in 1998, noting that it is rarely used.

A total of 208 people - mostly cancer patients - decided to take the lethal prescription from 1998 through 2004, the last figures available.

The Oregon law has already provided a model for California and Vermont, where the state legislatures are considering similar laws.

“I would suspect that, with the momentum with California, and now with the Supreme Court decision, that other states might follow,” said California state Assemblyman Lloyd Levine, a Democrat who co-authored the proposed assisted suicide law now under consideration.

Levine said various polls have shown broad support in California across demographic groups, both political and religious - including Democrats and Republicans, and Protestants and Catholics.

Michael Sirotkin, spokesman for Death with Dignity Vermont and End of Life Choices Vermont, said polls in the New England state also showed broad support for an assisted suicide law based on the Oregon model.

“It's incredible the number of personal stories that you hear that identify with the issue,” Sirotkin said. “You start talking about it and it's amazing how many people have stories to tell.”