These two Justices were both dissenters from a 1990 decision, Employment Division v. Smith, in which the Court refused to exempt members of an American Indian religion that uses peyote in its central ritual from a state law making criminal any use of peyote and other hallucinogenic drugs.

In that decision, written by Justice Scalia, the Court announced the principle to which Justice Kennedy's majority opinion adhered today: laws that happen to make a religious practice difficult or even impossible are constitutional as long as they are "neutral" and of "general applicability."

In their separate opinion today, Justices Blackmun and O'Connor said they still regarded the 1990 decision as incorrect. "The First Amendment's protection of religion extends beyond those rare occasions on which the government explicitly targets religion or a particular religion for disfavored treatment," they said.

Justice Souter, who was not on the Court when it ruled in the peyote case, wrote a 20-page separate opinion criticizing that decision today and calling on his colleagues to reconsider it in the next available case.

The Court's ruling in the peyote case provoked an uproar among many religious and civil liberties groups, and a bill to overturn it is advancing in Congress. The bill, named the Religious Freedom Restoration Act, was passed by the House of Representatives on May 11 and has not yet come to a vote in the Senate.

The split opinions today answered the question of why the Court had taken so long to decide the Hialeah case. The case, argued on Nov. 4 of last year, was the oldest undecided case on the Court's calendar. A Religious Hybrid

Santeria (pronounced sahnt-ah-REE-ya) is practiced today by some 70,000 Cubans living in South Florida, and experts put the number nationwide at many thousands, with concentrations in New York, Chicago and other cities with large Caribbean Hispanic populations. It is a blend of religions, mixing the traditional Yoruba religion, brought to Cuba by Africans who came there as slaves, with the Roman Catholic faith they found there.