The Supreme Court appeared hostile yesterday to a Michigan man's claim that a mandatory prison sentence of life without parole for possession of 1 1/2 pounds of cocaine constitutes cruel and unusual punishment.

Ronald Harmelin, now 45, had no history of violence and no criminal record when arrested in 1986 and sentenced under a 1978 Michigan law requiring life without parole for possession of more than 650 grams of cocaine.

Harmelin's argument relied on a 1983 case, Solem v. Helm, in which the court struck down a sentence of life without parole for a repeat offender who had six prior nonviolent felony convictions and wrote a bad $100 check.

But when Harmelin's lawyer, Carla J. Johnson, contended at the start of oral argument yesterday that his sentence violated guidelines set out in Solem about when sentences are so disproportionate to the offense as to be unconstitutional, Chief Justice William H. Rehnquist interrupted.

"Solem v. Helm was a 5 to 4 decision," he noted. Just three years before that ruling, he said, the court had upheld sentencing of a man to life with possible parole for a theft conviction after a third nonviolent felony.

Johnson, invoking the principle of stare decisis, responded that the court should not discard its precedents lightly.

"How do you think they treated stare decisis in Solem v. Helm?" asked Rehnquist, who had dissented in that case on the grounds that it was inconsistent with the earlier decision, Rummel v. Estelle. Two justices in the Solem majority have left the court and have been replaced by Justices Anthony M. Kennedy and David H. Souter.

Kennedy also seemed to join criticism of Solem, which the state of Michigan has urged the court to overrule. "You see no conflict in the reasoning of the cases?" he asked Johnson. "I must say I think the cases are difficult to square."

Harmelin's argument that the Michigan law violates the Constitution because it gives judges no discretion to consider individual circumstances and because it is out of line with penalties imposed for similar crimes in other jurisdictions encountered seemingly hostile questioning.

"Isn't a state entitled to feel more deeply about some crimes than other states do?" Justice Antonin Scalia asked, noting that illegal drugs can result in loss of life. "Why can't Michigan say, 'By George, we're going to put a stop to it?' "

Scalia asked repeatedly why a mandatory sentence of life without parole would be unconstitutional if a mandatory 20-year sentence for a 70-year-old, also likely resulting in the defendant's death in prison, would not.

"You tell us life in prison is different," he told Johnson.

Justice John Paul Stevens came to the lawyer's rescue. "It's not very different only in the very rare case of your hypothetical," he said, taking the unusual step of directly addressing another justice on the bench.

Justice Sandra Day O'Connor, who also dissented in Solem, told Johnson that it was "reasonably clear" that mandatory sentences are constitutional outside the context of death-penalty cases. She also noted that prosecutors retain discretion in deciding what charges to bring.

Johnson argued that mandatory life in prison means death in prison and should be allowed only to punish murderers. "Is that what your argument hinges on?" Souter asked, apparently skeptical. "If not, what do we have left?"

Oakland County Prosecuting Attorney Richard Thompson, defending the law, urged the court to "send a clear signal" to states that, "under the war on drugs, tough penalties such as Michigan's are constitutionally permissible."

But Johnson contended that the law is not working to deter drug dealing and is snaring only low-level drug couriers. "What are you going to do next, cut their arms off?" she asked.

In other action, the court let stand an appeals court ruling that requires the Army to allow a homosexual to reenlist. The court refused to hear the Bush administration's challenge to reinstatement of Perry Watkins, a 16-year Army veteran.

A federal appeals court had ordered the Army to take the action, not on grounds that the military's ban on homosexuals violates constitutional rights but because Watkins had told the Army that he was gay before being drafted and previously had been allowed to reenlist repeatedly.