Supporters of physician-assisted suicide for terminally ill patients won an important victory Tuesday at the U.S. Supreme Court.

The Justices held, in a 6-to-3 vote, that a 1997 law used to end the lives of seriously ill patients in the western state of Oregon takes precedence over the federal government's authority to regulate doctors.

Attorneys for the Bush administration argued that prescribing drug overdoses to terminally ill patients to assist in their suicide is not a legitimate medical practice, and is unlawful under federal drug laws.

But Justice Anthony Kennedy, writing for the majority, disagreed, saying the authority claimed by the Attorney General, who brought the case, is both beyond his expertise and incompatible with the law's purpose and design.

The ruling is a significant defeat for the Bush administration, which tried to convince the high court that the federal laws governing the actions of doctors should have outweighed Oregon's assisted suicide law.

Since the Oregon legislation known as the Death with Dignity Act was passed in 1997, it has been used to end the lives of more than 200 seriously ill people. No other state allows terminally ill patients to ask their doctors to prescribe a lethal dose of drugs.

George Eighmey, who heads Compassion and Dying in Oregon, an advocacy group that supports physician-assisted suicide, says the Court's ruling could change that.

"Not only is it going to go beyond the borders of the state of Oregon, with regard to our law, I think other states are going to see this as the green light to go ahead and pass similar laws in their states," said George Eighmey.

Eighmey says the ruling is a victory for all Oregonians who support having the right to another option at the end of their life.

Other advocacy groups support the Bush administration's effort to stop doctor-assisted suicide in Oregon. Wesley Smith, of the International Task Force on Euthanasia and Assisted Suicide, was disappointed with the Court's decision.

"This is going to renew efforts to spread this kind of non-medical treatment, that is killing as an answer to human suffering," said Wesley Smith.

Justice Antonin Scalia, writing the dissent, said federal officials have the power to regulate how medicine is distributed, and that would certainly exclude prescribing drugs to produce death. He acknowledged the emotionally-charged nature of assisted suicide, saying many people feel that the subject of assisted suicide is none of the federal government's business.

Joining Justice Scalia in dissenting were Justice Clarence Thomas, and for the first time, newly-appointed Chief Justice John Roberts.

Oregon's law covers only extremely sick people - those with incurable diseases, whom at least two doctors agree have six months or less to live, and are of sound mind.