In a speech at the University of Minnesota two years ago, Justice William Rehnquist downplayed the ability of presidents to choose Supreme Court justices who would invariably interpret cases from the point of view of a certain political philosophy. Times and issues change, he said, and so do judges, and no chief executive can be sure his nominee will vote in a predictable way.

This week, only two days after he was nominated to head the court, an opinion he had written was handed down that gives approval to a broad definition of sexual harassment. True, it was a unanimous opinion, and it sustained an interpretation of the statute that had been favored by the government. Nevertheless, Justice Rehnquist's role probably came as a pleasant surprise to civil rights advocates who have seldom found him in their corner in the past.

The case was brought by Mechelle Vinson, who alleges that she was sexually harassed by Sidney Taylor, her supervisor at the Meritor Savings Bank in this city. Though she suffered no economic damage because of this discrimination and her participation in a sexual relationship was voluntary, the court found that she could still have a cause of action. The Civil Rights Act of 1964 can be violated if sexual harassment -- unwelcome advances, requests for sexual favors and other verbal or physical contacts of a sexual nature -- has created a hostile or offensive working environment. There is no need to demonstrate that job retention, salary or promotion decisions were affected. Nor is it necessary to show that the complainant's participation was involuntary. The relevant question, the court held, is whether sexual advances were unwelcome.

Is the bank in this case liable for Mr. Taylor's conduct? That's not clear. The corporation had adopted a policy against discrimination and had set up a mechanism for dealing with grievances. Miss Vinson did not use this mechanism; in fact, she did not even complain about the alleged harassment until a year after it had stopped and she had been fired for another reason. Normally, however, a corporation would be liable for the acts of an agent or supervisor -- in this case, Mr. Taylor -- even if his conduct was not specifically authorized. The justices refused to decide the question of corporate liability in this case, but it will be reconsidered when the whole case comes before the trial court for further proceedings.

Miss Vinson may not win her case when it is retried. But if she loses, it will be because of the specific facts involved, not because the law does not forbid the kind of sexual harassment she has described. The case is a major victory for working women, and Justice Rehnquist's role in its resolution is particularly welcome.