Five years ago, when liberal members of the Supreme Court managed to scrape together a five-justice majority to overrule a 1976 case limiting the federal government's power over states, Chief Justice William H. Rehnquist issued a dissent -- and a prediction.

Some day, said Rehnquist, the author of the jettisoned decision, his view of federalism would prevail. "I am confident," he said, that his position will "in time again command the support of a majority of this Court."

With the retirement of Justice William J. Brennan Jr., that time may have arrived.

The dispute over an arcane though important question of the scope of congressional authority over the states underscores the broad potential impact of Brennan's departure and the tenuous hold of some key liberal victories.

Most public debate since Brennan's surprise announcement has focused on the future of abortion rights. Without Brennan, it is clear, the 1973 Roe v. Wade decision -- in which seven justices agreed that there is a fundamental constitutional right to abortion -- now has just three firm supporters on the court: its author, Justice Harry A. Blackmun, and Justices Thurgood Marshall and John Paul Stevens.

But the resignation of the court's foremost liberal has far larger implications for the future of constitutional law and the role of the court in some of the most divisive social issues of the day.

Brennan's absence, combined with the likely confirmation of federal appeals court Judge David H. Souter, nominated last week by President Bush to replace him, strengthens the court's fragile conservative majority. It is likely to tilt the balance of power in conservatives' favor in cases involving civil rights, separation of church and state, the role of the federal courts, and the power of states versus the federal government.

While conservatives already have the upper hand in such areas as capital punishment and the rights of criminal defendants, the addition of another conservative voice could mark an end to the already rare instances in which liberals are able to cobble together a majority in such cases, and a further erosion of already weakened precedents in the criminal law area.

"All the chips are in the middle of the table," said Charles J. Cooper, an assistant attorney general in the Reagan administration and architect of much of its legal philosophy. "We may well be on the precipice in which the court will stablilize and become predictably conservative in the same way that the Warren court was predictably liberal," Cooper said.

"There are a large number of cases in many important areas where a switch of one vote could have severe consequences. . . . The doctrines are at risk," said Norman Dorsen, president of the American Civil Liberties Union.

The shift, when it comes, will be the culmination of a process that began with the appointment of now-retired Chief Justice Warren E. Burger in 1969.

With Souter, Republicans will have made nine consecutive appointments to the high court (although two of those picks, Richard M. Nixon's selection of Blackmun and Gerald R. Ford's selection of Stevens, have turned out to be disappointments to conservatives.) The last justice to be named by a Democratic president was Marshall, in 1967.

The new court may not manifest itself dramatically overnight. It takes time for some issues to percolate up through the lower courts to the Supreme Court. The court's respect for precedent -- even decisions with which a majority may now disagree -- may put a brake on wholesale change.

And the justices are not likely to disturb some of the Warren court's landmark rulings, now entrenched in the law and society -- cases like the Miranda decision, the one-man, one-vote ruling, or the decision excluding prayer from public schools.

"I think there will be a sense on the part of a substantial number of the conservative justices about preserving the court's capital and not going so fast that it impairs the court's prestige as an institution," said University of Chicago Law School dean Geoffrey Stone, a former Brennan clerk.

But whether Souter turns out to be an outspoken, aggressive advocate for change in the manner of Justice Antonin Scalia or a swing voter and force for narrowly written rulings in the mode of Justice Sandra Day O'Connor, the likelihood appears high of an eventual -- and perhaps a speedy -- transformation in some of the most controversial areas within the court's purview.

An examination of the dwindling number of 5 to 4 rulings during Brennan's final years on the bench offers a road map of the areas of likely change. During the last term, for example, he voted with the majority in a dozen 5 to 4 decisions.

A few of those rulings, like the decision striking down the federal flag desecration statute, did not break down along ideological lines. Two of the court's most conservative members, Scalia and Justice Anthony M. Kennedy, provided the margin of victory in the flag case, and how Souter would vote if confronted with such a statute cannot be predicted.

But others -- expanding Congress's power to enact affirmative action programs; allowing federal judges to order local school boards to raise property taxes to pay for desegregation plans; or striking down most political patronage in hiring and promotion -- appear unlikely to survive on a court without Brennan.

Justice Byron R. White provided the margin of victory in each of those cases. "If we assume for a moment that Souter will be more like Rehnquist than like White, then White becomes irrelevant in terms of the transition of this court to a more reliably conservative court," Cooper said.

The impact of the change could be felt as early as the term beginning Oct. 1, when the court hears its first school desegregation dispute in more than a decade. The case involves Oklahoma City's attempts to dismantle its court-ordered busing plan and could determine the duties of school boards throughout the country to maintain desegregated schools.

The court also will decide a sex-discrimination case involving whether companies can exclude fertile women from certain jobs in order to protect their fetuses, and it will consider whether punitive damages can be so large as to violate due process.

And, in a case that could offer the first glimpse of Souter's view on both abortion and free speech, the court will review Reagan administration regulations that prohibit federally funded family planning clinics from providing any information about abortion, although it is unlikely that the court in that case will confront Roe head-on.

In the longer run, however, the abortion decision is clearly in jeopardy. With Souter apparently hostile to the idea of affirmative action, as indicated in a 1976 speech, the court is also likely to cut back on congressional power to enact affirmative action programs (following on its 1989 decision restricting state and local power), and perhaps to limit the ability of employers to adopt voluntary racial preference programs as well.

With the addition of Souter, the court could go further in what Dorsen and other civil libertarians view as the dismantling of the wall between church and state, allowing more government aid to religious groups and parochial schools or perhaps upholding a moment of silence in public schools.

In the criminal law area, some of the few liberal victories in the past several years are candidates for overruling -- for example, the decisions excluding "victim impact" statements from consideration in death penalty cases.

And it is likely to continue what Brennan and his fellow liberals have asserted is the "evisceration" of Fourth Amendment protections against unreasonable search and seizure.

Some areas, like protections for freedom of speech, at least outside the area of pornography, may be relatively unaffected. "The First Amendment freedom of speech is the most likely to continue," said Harvard Law School professor Kathleen Sullivan, a liberal. "There's almost a sacral attitude toward freedom of speech, even among the conservatives."

Rapid change, however, would not be unprecedented. "Once the New Deal formed its liberal juggernaut, it overturned 26 cases in four years," noted conservative legal scholar Bruce Fein. "They had to rewrite volumes on the commerce clause, economic liberties, states' rights in that short a period. . . . So what's the institutional restraint?"