Supreme Court Justice William H. Rehnquist said yesterday that the court serves "the public good" by cloaking its deliberations in secrecy even if the other branches of government serve it with increasing openness.

In a rare public defense of the secret deliberations by a member of the court, Rehnquist said the public would lose more than it would gain if the nine justices were to admit the press to their conference.

The conference, hld in a room adjoining the chambers of the chief justice, are the closed forims.

Supreme Court Justice William H. Rehnquist said yesterday that the court serves "the public good" by cloaking its deliberations in secrecy even if the other branches of government serve it with increasing openness.

In a rare public defense of the secret deliberations by a member of the court, Rehnquist said the public would lose more than it would gain if the nine justices were to admit the press to their conference.

The conference, held in a room adjoining the (hambers of the chief justice, are the closed forums at which they have heard arguments in open court and decide whether to hear appeals and approve petitions for review of decisions made by lowercourts.

"From public sessions of oral argument and published opinions and orders, we already know precisely what business the Supreme Court transacts, and we know a fair amount about how it transacts that business." Rehnquist told the Washburn University School of Law in Topeka.

"The deliberations of the court's conference are not public, and should not be made public, because the added information about the workings of the court which would result would be more than offset by the probability that the usefulness of the conference as a deliberative institution would be seriously imparied," he contnued.

"The very process of reporting its deliberations could significantly change, and for the worse, the nature of those deliberations," he added.

Arthur S. Miller, a professor of constitutional law at George Washington University who has written articles condemning excessive court secrecy as inimical to the democratic process sharply criticized Rehnquist's "orthodox" view.

Miller, asked to comment on the speech, said Rehnquist didn't want to disclose "the dirty little secret that the justices are always making law." as acknowledged by Justice Brown R. White in an opinion dissenting from a 1966 ruling that police officers have to advise suspects of their rights to keep silent and to have consel.

White wrote that the majority "does . . . underscore the obvious - that the court has not discovered or found the law . . . What it has done is to make new law and new public policy . . . This is what the court historically has done. Indeed, it is what it must do will continue to do until and unless there is some fundamental change in the constitutional distribution of governmental powers."

Miller said that the "basic democratic theory and practice" of law making entitle the public to know "not only what the rules are, but how those rules are established" in a body where a single swing vote can validate or invalidate an action of any unit of the federal or state governments.

he compared the secrecy surrounding Supreme Court deliberations with that of decision-making about the war in Vietnam, saying that the court and the executive branch share a "distrust" of the ability of the people "to withstand knowing the internal operations of the governing process."

Rehnquist said the court has two choices: continue the status quo or open its deliberations to the public and to the press."

Miller told a reporter that he rejects "the polar opposites" of no press coverage at all or of complete coverage, "which would bore the people to death."

But, he said, at some point after final disposition of a case the court could, for example release minutes of the pertinent deliberations as well as the notes taken by each justice.

Such a course would enable the public to seek answers to vital questions, such as how compromises have been reached and "whether justices worked back from principles to conclusions." Miller said.

The justices also should allow unobtrusive cameras and microphones to carry oral arguments in open court to the public he suggested.

The secrecy of court deliberations began - "for reasons now lost in antiquity" - under Chief Justice John Marshall, who served from 1801 through 1835. Miller and D.S. Sastri wrote in the Buffalo Law Review four years ago.

Thomas Jefferson protested the secrecy in a letter in 1321. Another most condemnable practice of the Supreme Court is that of cooking up a decision in caucus and delivering it by one of their members as the opinion of the court, without the possibility of our knowing how many, who, and for what reasons each member concurred," he wrote. "This completely defeats the possibility of impeachment by smothering evidence."

Through the years, various justices have offered an occasional defense of conference secrecy. Justice William J. Brennan Jr. once said, for example, that it is necessary for "obvious resons."

Such arguments have been reinforced by leaks. These have been rare, although less so in the 19th century when, the late Cheif Justice Earl Warren once said, the court was "much more political" than today. In this century, one memorable leak occurred four years ago when Time magazine detailed the court's abortion decision before it was delivered.

Apparently the Rehnquist speech is the first full-blown defense of the court's conference secrecy. The justice said in his speech that he had "a rather difficult time selecting a topic" because of the court's prohibition on discussion of pending cases.

He argued that "the public good, and not private preferences," must control whether public officials justifiably can discuss public matters in private.

Similarly, he said, the media may want to report "the internal deliberations, jockeying manuevering, arguing, or what have you," but "have no claim of their own independent of the public good or whatever you may choose to call it."

But the secrecy of the conference - "a somewhat fragile institution"- serves the public more than the additional information that press coverage would provide, he said, arguing that:

The justices can have "a remarkably candid exchange of views . . . No one feels at all inhibited" about the possibility of being quoted or of "half-formed or ill-conceived ideas" later being" held up to public ridicule."

With no one else in attendance, not even law clerks, each justice, unlike a Cabinet member "generally flanked by aides," is formed "to prepare himself for the conference deliberation."

Public scrutiny of deliberations could generate "lobbying pressures" intended to affect decisions before they become final.

The conferenes are marked by "occasionally short-tempered remarks or bits of rancorous rhetoric," but this is transcended by a cordiality among the justices that might not survive being spread on a public record.

Rehnquist said the conferences should remain closed in the public interest even if opening them would not largely destroy their usefulness and even if the values of candor,preparation and harmony were not really essential.

"I think we must be careful to avoid making the varios branches of government . . . resemble cockpits" that deter citizens from becoming public servants, if the purpose is merely "enabling the press toget a good story," he said.