With the new chief justice, John G. Roberts Jr., in dissent in the most high-profile case since he joined the court, the decision lifted a major barrier to state initiatives like the one in Oregon, which has the only assisted-suicide law in the country.
Justice Anthony M. Kennedy's majority opinion did not say that Congress could not act to block such laws, only that it had not given Mr. Ashcroft the "extraordinary authority" that he claimed when he threatened Oregon doctors who followed the state law with losing their federal prescription-writing privileges.
While the court's decision was based on standard principles of administrative law, and not on the Constitution, it was clearly influenced by the majority's view that the regulation of medical practice belonged, as a general matter, to the states. Mr. Ashcroft acted contrary to "the background principles of our federal system," Justice Kennedy said in his 28-page opinion.
The decision on Tuesday upheld rulings by two lower federal courts. Mr. Ashcroft, while attorney general, appealed to the Supreme Court in November 2004. His successor, Alberto R. Gonzales, embraced his position and pursued the appeal after the justices agreed last February to hear the case.
Chief Justice Roberts did not write a dissenting opinion, instead signing a dissent written by Justice Antonin Scalia. For those eager for any hint about the new chief justice's predilections, his silent joining of this strongly worded opinion was intriguing. When the case was argued on Oct. 5, his second day on the bench, Chief Justice Roberts was an active participant but did not tip his hand.
At his confirmation hearing, he had declined to answer questions about his personal views on issues like assisted suicide, saying a judge's views and values should play no role in his judicial decisions.
Justice Clarence Thomas did write a dissenting opinion, saying it was "perplexing to say the least" to find the court interpreting federal drug law narrowly in this instance when only months ago, it upheld broad federal authority to prevent states from authorizing the use of marijuana for medical purposes.
Oregon voters approved the Death With Dignity Act in 1994 and affirmed it 1997. The law says that doctors who follow specific procedures may prescribe lethal doses of federally regulated medications to help their mentally competent, terminally ill patients end their lives. Through 2004, 325 people had obtained the lethal prescriptions, and 208 had used them.
When the Oregon measure took effect, Mr. Ashcroft was a senator from Missouri. Along with other members of Congress, he asked the Clinton administration to take steps to block the law. Attorney General Janet Reno refused, writing to Congress in June 1998 to say she had no authority to act because there was no evidence that Congress "intended to displace the states as the primary regulators of the medical profession." Mr. Ashcroft then co-sponsored a bill to give the government this authority, but it did not pass.
As attorney general, Mr. Ashcroft announced in November 2001 that doctors who prescribed lethal doses of drugs for the purpose of assisting a suicide risked losing their federal licenses to prescribe all "controlled substances." Without such licenses, doctors would find it difficult to practice medicine because controlled substances include many prescription pain relievers and other commonly used medications.
Oregon sued to block the new rule, joined by a doctor, a pharmacist and several terminally ill patients.
As authority for his action, Mr. Ashcroft invoked the Controlled Substances Act, a 1970 law that established the framework for federal drug policy, as well as a regulation issued by the Justice Department the following year that put the law into effect. The regulation requires that every prescription for a controlled substance "be issued for a legitimate medical purpose." Assisted suicide is "not a legitimate medical purpose," Mr. Ashcroft said.
In his opinion on Tuesday, Gonzales v. Oregon, No. 04-623, Justice Kennedy emphasized, with evident disapproval, the unilateral nature of Mr. Ashcroft's action, taken "without consulting Oregon or apparently anyone outside his department." The attorney general's rule was not entitled to the deference the court usually gave to interpretations of governing statutes by executive branch officials, he said, because Congress had not given the attorney general the authority he was invoking.
"The authority claimed by the attorney general is both beyond his expertise and incongruous with the statutory purposes and design," Justice Kennedy said.
Justice Scalia, in his dissenting opinion, took issue with the argument that Congress could not have intended to delegate medical judgments of this sort to the attorney general. The legitimacy of physician-assisted suicide "ultimately rests, not on 'science' or 'medicine,' but on a naked value judgment," he said, adding, "It no more depends upon a 'quintessentially medical judgment' than does the legitimacy of polygamy or eugenic infanticide."
Justice Scalia said Mr. Ashcroft's action was "the most reasonable interpretation" of the statute because "virtually every relevant source of authoritative meaning confirms that the phrase 'legitimate medical purpose' does not include intentionally assisting suicide."
In the few months since the case was argued on Oct. 5, the question of how skeptically the Supreme Court will be willing to examine the exercise of power by the executive branch has become considerably more prominent. This issue also seemed to mark a divide between the majority and the dissent.
In his opinion, Justice Kennedy said that Mr. Ashcroft was claiming the "extraordinary authority" to declare as criminal actions that Congress had not designated as crimes, and that he was seeking "a radical shift of authority from the states to the federal government to define general standards of medical practice in every locality."
But Congress had no such intent in passing the Controlled Substances Act, Justice Kennedy said. "The structure and operation of the C.S.A. presume and rely upon a functioning medical profession regulated under the states' police powers," he said, adding that "Oregon's regime is an example of the state regulation of medical practice that the C.S.A. presupposes."
Justices John Paul Stevens, Sandra Day O'Connor, David H. Souter, Ruth Bader Ginsburg and Stephen G. Breyer signed the majority opinion.
The court was clearly aware that it was venturing into "an earnest and profound debate," as Justice Kennedy noted, quoting from the court's 1997 opinion in an assisted-suicide case. In that case, Washington v. Glucksberg, the court said that the Constitution did not convey a right to assistance in dying, but that states were free to experiment with the issue. "The dispute before us," Justice Kennedy said, "is in part a product of this political and moral debate."
Scott McClellan, the White House press secretary, said at his briefing on Tuesday, "We are disappointed at the decision." Mr. McClellan added, "The president remains fully committed to building a culture of life, a culture of life that is built on valuing life at all stages."