FOR DECADES, the nation has been debating the merits of liberal judicial activism -- the effort to achieve broad social reform through the federal courts. That debate is over.

It's over no matter how President Bush's nominee to the Supreme Court, the mysterious David Souter, fares in the confirmation process and no matter how he might vote on the court. For many, the debate appears to have ended with the departure of Justice William J. Brennan Jr. Without Brennan's brilliance and his singular skills as a coalition-builder, the court no longer seems the branch of first resort for liberals. They'll have to turn elsewhere.

But the fact is, they already have. While the judicial news in the Reagan and Bush eras has been about a movement to the right, the legislative news has been otherwise. Last week, for example, President Bush signed a far-reaching law expanding the rights of the handicapped. Ralph Neas, executive director of the Leadership Conference on Civil Rights, called it "the most dramatic and significant improvement in civil rights law in 25 years."

In the meantime, congressional liberals are faring quite well in their battle to win the strongest possible language in codifying affirmative action policies that the Supreme Court rejected last year. That's not a new departure: Neas notes that since 1982, Congress has regularly defended a liberal view on civil rights against assaults from the courts or the executive branch.

The lesson is clear: Despite much understandable liberal mourning over the Brennan resignation, liberalism is not dead just because Brennan is gone. It has simply found a new venue. And in having to rely more on Congress and the political process -- slow and cumbersome though they can be -- liberals may find themselves better off.

For decades, liberals have been torn by arguments over how much they should rely on the courts to achieve their ends. Since the Brown v. Board of Education desegregation decision in 1954, said Cass R. Sunstein, a law professor at the University of Chicago, "people have been trained to think that the court is where you go for social reform."

Not so long ago, things were different, as Franklin D. Roosevelt learned when a conservative Supreme Court kept frustrating his New Deal program. The original push for civil rights, in the Reconstruction Era after the Civil War, came from Congress.

Indeed, notes Walter Dellinger, a law professor at Duke University, the Reconstructionists "expected that it would be future Congresses that would protect equality and liberty," not the courts. That hope was foiled by the power that southern segregationists wielded in Congress from the 1890s through the 1950s. It took the Supreme Court, Dellinger said, to break that deadlock. What followed were three decades of court rulings that, among many other things, overturned malaportioned legislatures and congressional districts, increased the rights of those accused of crime and strengthened civil rights guarantees.

But even in the Warren court's heyday, many of the most important monuments to liberalism still came from Congress and political action. "Martin Luther King may well have been a more important source of constitutional change than all of the Warren court's race decisions," Sunstein argued in an article published this year in The American Prospect. Southern schools, Sunstein noted in an interview, were integrated only after the enactment of the 1964 Civil Rights Act, passed under pressure from the movement that King led.

The 1965 Voting Rights Act is an example of how social reform won through political struggle can be more enduring than anything won through court action. Because of the electoral power that blacks won in the South, Sunstein notes, southern Democrats -- once the bulwark of segregation -- have become rather reliable supporters of civil rights causes.

One who learned this the hard way was Robert Bork, whose nomination to the Supreme Court was finally beaten by the votes of conservative southern Democrats whose margins of victory came from black voters.

None of this is to say that liberals won't miss a federal judiciary that was reliably on their side -- especially if they should someday lose the Congress. Dellinger observes that while Congress is likely to uphold a generally liberal view on civil rights, "It's harder to imagine Congress providing protection of individual dissidents like flag burners."

And adding a conservative justice to the court -- or even a moderate, if that's what Souter turns out to be -- could encourage court conservatives to upset liberal precedents.

"The court is generally reluctant to overturn precedent on a single vote, for fear that the law will become unsettled again," Dellinger said. "But if six justices think the old precedent was wrong, there's a better chance the new precedent will stand." Terry Eastland, a resident scholar at the conservative National Legal Center in the Public Interest, agrees. "You'll have fewer 5 to 4 decisions," he said, "which means you'll have bolder 6 to 3 decisions."

Eastland thinks that liberals should be at least mildly reassured by the conservatives' reluctance to enagage in "judicial activism." Liberals aren't so sure. On many issues, Sunstein said, conservatives are quite willing to overturn liberal legislative handiwork.

For example, many conservatives want to toss out laws restricting presidential power. A conservative court could sharply limit congressional claims to broad power under the 14th Amendment -- the basis for most civil rights legislation. It might be more willing to use an expansive view of property rights, which could narrow Congress's ability to act on some economic questions.

In losing the court, moreover, the liberals will lose what can be a more effective bully pulpit than the presidency. In its decisions on issues ranging from civil rights to abortion, the post-World War II Supreme Court altered the national consensus, sometimes by confronting Americans with a new set of mores. Dellinger refers to "the normative power of the actual." Many Americans, for example, have become so accustomed to having abortion legal nationwide that they will find it hard to accept the alternative, a patchwork of abortion laws that will place women in different states under vastly different restrictions. But by relying so heavily on the courts, liberals often failed to build public support for their victories -- and paid the price later in elections. "Instead of building majorities, all you needed was one plaintiff to make your way up the Supreme Court," said Eastland. Nathan Glazer, a sociologist at Harvard University, argues that the rise of the religious right can be largely understood as a reaction to liberal court decisions, "a defensive offensive," Glazer calls it.

There are also limits to how much reform the courts can enforce. While courts have ordered legislatures to spend money for a variety of causes, the courts cannot produce the money; only taxpayers and politicians can. The courts can expand the rights of the mentally ill, but they cannot easily address their problems when they become homeless street people.

Few issues better illustrate the political peril of judicial victory than abortion. When the Supreme Court affirmed a right to abortion in Roe v. Wade, it effectively defused the abortion rights movement and energized abortion's foes. As it grew more powerful, the anti-abortion movement converted many leading Republicans -- notably Ronald Reagan and George Bush -- to their cause.

It was only after Roe v. Wade was threatened by the Supreme Court's Webster decision last year that the abortion rights movement mobilized -- and to extraordinary effect. While there is much legitimate dispute over how abortion is playing at the polls, few doubt that abortion rights activists have been helpful to key Democrats, notably Govs. L. Douglas Wilder of Virginia and Jim Florio of New Jersey, who were elected last fall.

Even a strong supporter of Roe v. Wade like Rep. Don Edwards (D-Calif.), the chairman of the Subcommittee on Civil and Constitutional Rights, believes that something was lost when the court, instead of the political process, decided the abortion issue. "By having the court snatch it away from us, it caused all kinds of resentments," Edwards said. "There are people who think it would have been better if abortion had been legalized by popular demand rather than by thunderbolt."

For Edwards, there are many advantages to winning reform through politics. "There's a better dialogue," he said. "It's an educative process." A dramatic example of this, he said, was the debate on the constitutional amendment to ban flag burning. At the end of the debate, voters understood "that we were protecting the Bill of Rights and not supporting flag burning." His constituents, Edwards said, no longer raise the flag issue.

Still, the flag issue also points to the problems liberals will face in the new era. The debate happened only because the Supreme Court threw out a bill that Congress had passed. The lesson is that congressional liberals will have to do most of their "educating" without the court's help.

The new situation will require greater discipline from liberals in other areas. Happily for them, they are beginning to show it.

The ongoing discussions on the civil rights bill are a nearly perfect demonstration of how the new world will work. Sen. Edward M. Kennedy (D-Mass.), the lead Senate negotiator with the White House on the affirmative action proposal, said the talks have been difficult because liberals are aware that they need to make the language extremely specfic. "There's little doubt that when we draft these bills," he said in an interview, "we do so with a hostile court in mind." So concerned were Senate liberals with how the courts might interpret the bill that they actually told the courts how to interpret it, and all other civil rights laws besides. Among other things, the bill advises that civil rights laws "shall be broadly construed . . . to provide equal opportunity and provide effective remedies."

Kennedy noted that White House Chief of Staff John Sununu was quite prepared to keep the bill's affirmative action language somewhat vague and "leave it up to the courts for interpretation." In the old days, Kennedy said, liberals could count on the courts for "generous" interpretations; now, conservatives look to the courts for narrow ones.

What the liberals don't get out of Congress, they may try to find elsewhere, for example from state courts in places where the judiciary is still liberally inclined. The turn to the states was proposed by, among others, William Brennan, who in a 1986 speech urged the states to "step into the breach."

Abortion rights advocates have begun to pursue this strategy and have won broad pro-choice interpretations of state constitutional provisions in Florida and California; advocates of equalizing the amounts school districts spend on their pupils have also done well in the state courts.

The best news of all for liberals is that even conservatives who look forward to a new era of jurisprudence do not expect the world to suddenly turn in their favor. Much of what Brennan and his allies achieved is very nearly irreversible. The one-person, one-vote decision, for example, has permanently changed the face of Congress and the state legislatures. Legislatures now dominated by urban and suburban interests will not readily vote to go back to the 1950s, when legislators representing tiny minorities from generally conservative rural areas could dominate the proceedings. Conservative critics of judicial activism are always careful to say that they agree with the Brown decision -- a sign of the depth of the liberal consensus. And even in the post-Reagan era, "the court is often lopsided and sometimes unanimous in a robust interpretation of First Amendment freedoms," said Kathleen Sullivan, a professor at Harvard Law School. Justice Brennan is one who believes the court's liberal era has transformed the nation. "This legacy can and will withstand the test of time," he said in announcing his retirement.

Conservatives reluctantly agree. "Liberals can take heart that a lot of conservatives think the damage has already been done," Eastland said. "A lot of these decisions will continue to fertilize the body politic for a long time to come." And in the coming years, the body politic is exactly where liberals will have to take their fights.

E.J. Dionne Jr. is a Washington Post reporter.