New Orleans

The three Supreme Court justices who spoke to the American Bar Association convention here over the weekend seemed to have something on their minds.

But it required a lot of decoding and interpreting to figure out just what it was.

Justice John Paul Stevens sounded as if he were addressing the Moral Majority and defending the Supreme Court's ban on compulsory prayers in the classroom. But he wouldn't, of course, say so explicitly.

Justice Lewis F. Powell Jr. sounded as if he were serving notice on President Reagan. No matter how many judicial nominations a president makes, Powell seemed to say, he cannot be sure of tilting the court his way. But Powell, of course, never said so directly.

A few blocks away, Justice Byron R. White was privately urging reporters to skip his speech, which he said would be a bore, and instead to cover a panel at another hotel on the right-wing movement to strip the court of jurisdiction over controversial social issues. Would White comment on that controversy, he was asked. Of course not.

But he said that maybe the Justice Department representative on the jurisdiction panel would take a position. He didn't.

ABA conventioneers do not really expect content from such speakers. The very presence of a Supreme Court justice seems sufficient. For the law, some say, is the civic religion. This convention is its annual rite and the justices are its high priests. They confer sanctity just by showing up. Whether or not their jokes are funny, people laugh. No matter what they say, people in the audience nod approvingly and get in line to shake hands.

"What, my friends, is the ultimate source of the liberty that is protected by the federal Constitution from deprivation without due process of law?" Stevens asked at the conclusion of a 20-minute talk that seemed to be on the subject of school prayer.

"What is the ultimate source?" reporters looking for leads asked Stevens later.

"I asked the question," he replied. "You answer it."

Was he defending the court's rulings on school prayer, reporters asked. "The speech speaks for itself," he said.

That is true because Stevens said it was true. But, like many of the court's opinions, getting a justice to tell the world what he really means can be a challenge. Fear of prejudicing their role in a future case accounts for this phenomenon, justices have said in the past. Or perhaps it is their way of preserving the mystique.

So most of them (with the recent exception of Chief Justice Warren E. Burger on the subject of crime and punishment) speak in codes. They do this even when they are trying to be funny.

"After 'The Book' was published," Powell told an ABA audience in an apparent reference to The Brethren by Bob Woodward and Scott Armstrong, "whenever I went anywhere I was asked if we were still speaking to each other.

"Now a different question is put to us, chiefly by people in the Reagan administration, who wistfully ask: 'Tell us about the health of the justices.' " (Laughter from the audience.)

"As a matter of fact," Powell continued, "the nine old men, only eight of us now . . . several of us have bought new suits. And there is even a rumor that some changes may be made in the court's plumbing." (More laughter.)

After saying the all-male court "would welcome" Sandra D. O'Connor, Powell noted that "the justices with the most impeccable political credentials rarely have remained loyal supporters of the political goals of the presidents who appointed them."

There seemed to be a topical message there. But just when it seemed Powell would make some news, he shifted gears, plunging into such subjects as Morrison Waite and Melville Fuller, two chief justices of the 1880s.

Stevens required even more deciphering. The setting was an ABA prayer breakfast.

Quoting Justice Harlan Fiske Stone, Stevens took up the subject of early rulings on compulsory saluting of the flag at school. Then, citing Patrick Henry, Stevens seemed ready to get to the meat of the speech: to "dramatize the distinction between a compelled ritual and voluntary participation in a common exercise."

"Not one of you was compelled by your sovereign or by your pastor to attend" the prayer breakfast, he said. "By attending, you have silently implied that voluntary prayer and reflection are appropriate on a Sunday morning."

Does that mean that prayers in school are inappropriate? Stevens wouldn't say.