The Supreme Court yesterday set aside a ruling that forced a Louisiana death-row prisoner to take antipsychotic medication so he could be made sane enough to be executed.

In an unsigned, one-sentence opinion, the justices sent the case of convicted murderer Michael Owen Perry back to the state court in Louisiana to consider the effect of a decision last year involving involuntary medication of prisoners.

Perry murdered his parents, two cousins and a 2-year-old nephew. Although he had a history of mental problems, he withdrew his plea of not guilty by reason of insanity and was found competent to stand trial.

After being convicted and sentenced to death, however, Perry -- who suffered from hallucinations, delusions of being God and other mental problems -- was found not sane enough to be executed unless he was given antipsychotic medication. The judge ordered that Perry be forcibly injected with Haldol, an antipsychotic drug.

The Supreme Court ruled in 1986 that it violates the constitutional prohibition of cruel and unusual punishment to execute the insane, and Louisiana does not execute insane prisoners. But the court in the 1986 case did not reach the issue presented by Perry's case: whether prisoners can be forced to take drugs to make them sane enough to be executed.

Last year, in a non-capital case called Washington v. Harper, the court said mentally ill prisoners could be medicated against their will in some circumstances.

But the court said prisoners retain a "significant liberty interest in avoiding the unwanted administration of antipsychotic drugs" and restricted medication of prisoners against their will to situations where "the inmate is dangerous to himself or others and the treatment is in the inmate's medical interest."

The court agreed to hear Perry v. Lousiana the week after the Harper ruling, and it was unclear yesterday why the justices waited until the case had been briefed and argued to decide to send it back to the Louisiana courts for reconsideration in light of Harper.

The effect of the ruling on Perry's fate also was uncertain.

Perry's lawyers argued at the Supreme Court that the order forcing medication on him violates the limits set in Harper because the medication is designed "solely as a means to groom Michael for execution," not based on his medical needs or any danger he poses.

Louisiana conceded that the medication was designed "primarily" to make Perry sane enough to be executed but contended that whatever constitutional right he had to refuse treatment was "extinguished" by the death sentence. Even if Perry, who is now being medicated, retained some right, the state added, it would be outweighed by the state's interest in carrying out "a validly imposed sentence of death."

Perry's lawyer, Keith Nordyke, said yesterday that he took the court's move as a positive sign. "Clearly this means that the liberty interest that was posited in Washington v. Harper is something that we've got to concern ourselves with in this case and that the state's interest in the death penalty does not override the liberty interest in refusing the unwanted medication," he said.

But Assistant Attorney General Rene Salomon said he believes the state can meet the test set out in Harper. "To me, if you can medicate somebody just because he's potentially dangerous to somebody's property, you can medicate somebody because he's killed five people," Salomon said. "He's obviously dangerous. He killed five people."

In other action yesterday, the court agreed to use a Maryland man's case to clarify how federal judges should calculate sentences under the federal guidelines for defendants who plead guilty.

The court said it would hear the case of Thomas Braxton, a patient at St. Elizabeths Hospital here who shot at U.S. marshals sent to apprehend him when he failed to report for his required medication after he was released into the community.

Braxton pleaded guilty to assault and weapons charges, and an attempted murder charge against him was dismissed. At his sentencing, he acknolwedged that he "did shoot at the marshals," and the judge used that as a basis for imposing a higher sentence of 51 months, compared with the 30 months he would have faced under the assault charge. Braxton also received a five-year sentence on the weapons charge.

Sentencing guidelines allow judges to base penalties on crimes more serious than those to which defendants have pleaded guilty if there is a "stipulation that specifically establishes" the worse crime. The question in Braxton v. U.S. is whether such a "stipulation" must be formal and written, or whether acknowledgements like Braxton's may suffice.