Civil rights groups are worried that a Supreme Court decision to reconsider a 12-year-old ruling on race discrimination could be the beginning of an effort to reverse basic legal advances for minorities.

Conservatives see it as signaling the possible end of an era where they believe legal principles were bent to favor minorities."The message is there's a new court now that Justice (Anthony M.) Kennedy is on board and previous rulings are up for grabs," said Ira Glasser, executive director of the American Civil Liberties Union. "It is an ominous development."

By a 5-4 vote Monday, the justices took the unusual initiative of broadening the scope of a North Carolina racial-harassment case so that they could consider limiting the ability of minorities to sue private citizens for monetary damages.

Arthur Spitzer, the ACLU's legal director here, said the court's action will have "enormous psychological impact" by indicating "basic civil rights decisions now may be considered open to attack."

A conservative constitutional lawyer, hailing the action, said it comes from a court "no longer willing to say, as it has in the past, that any statutory interpretation that is a victory for minorities automatically wins even if you've got to bend legal principles."

The lawyer, Bruce Fein, visiting fellow in constitutional studies at the conservative think tank Heritage Foundation, said the action could lead the court to take another look at other cases that represent "really almost absurd efforts to rewrite intent and legislative history."

"This indicates to me," Fein said, "that the court is going to take a hard look at statutory civil rights and be willing to overturn decisions where they were based on really flawed reasoning, even if the results are politically unpopular."

Kennedy, who joined the court in February, provided a fifth vote Monday to re-examine the 1976 ruling that expanded the right of minorities to sue over alleged discrimination.

The other four are Chief Justice William H. Rehnquist and Justices Byron R. White, Antonin Scalia and Sandra Day O'Connor. Scalia, O'Connor and Kennedy were appointed to the court by President Reagan, a frequent critic of rulings he regards as too liberal.

Justice John Paul Stevens, in a sharply worded dissent, said minorities may feel betrayed by the court's willingness to consider discarding an important civil rights precedent.

He said the action is unwise activism and will "have a detrimental and enduring impact on the public's perception of the court as an impartial adjudicator." He was joined by Justices William J. Brennan, Harry A. Blackmun and Thurgood Marshall.