A CASE BEFORE the Supreme Court involves the bending of seniority rules so that job layoffs will not wipe out recent progress in correcting the effects of past discrimination.

In the early 1970s, employees in the Boston police and fire departments were, respectively, 2.3 percent and 0.9 percent black and Hispanic. While strict proportionality should not be the litmus test in spotting subtle discrimination, here the courts were persuaded that the pool of qualified minorities interested in those jobs was much higher. They noted, for example, the Boston minority population figures--over 20 percent at the time. The defendants were unable to explain away the discrepancy. The courts concluded that there had been job discrimination, principally in the use of civil service exams unrelated to job requirements and in word-of-mouth recruiting.

The courts said that the Constitution and the Civil Rights Act required action that would produce a "significant increment" of minority officers "in the near term." Specifically, the judges required, with the consent of the parties, that civil service registers of certified job candidates be drawn so that minorities and whites would be listed in alternating order. The practical effect was to compel one-for-one hiring.

Success. By July 1981, minorities constituted 11.7 percent and 14.7 percent of police and fire personnel. But a fiscal crisis brought a layoff plan that would have all but erased that progress, because state law said last hired, first fired. The plaintiffs returned to court in hopes of preserving the hard- won gains, and the trial and appellate courts agreed that the layoff scheme should maintain the new percentages of minority workers. Now the Supreme Court will review the matter, and the Justice Department has switched sides in the case (a now familiar pattern) to support the white officers.

There are victims aplenty here. The original discrimination was not against particular individuals but against a class defined by race, though perhaps not intentionally so defined. Yet the one-for-one hiring remedy and the recent modification of seniority have identifiable white victims whose jobs came along with certain assurances about their future treatment. Although those officers as a class benefited from the past discrimination--some individuals might not otherwise have been hired--that benefit was quite remote.

All this suggests to us that solutions must be found that are not all one way or the other. Seniority should not be abandoned in its entirety; nor should groups that have suffered discrimination be told they have a remedy only in fair economic weather but not in foul. Remedies of the Boston sort can only be last resorts, available after courts explore every avenue to avoid injuries to those like the hapless white officers.

Seniority provides valuable protection from arbitrary firings. But deference to those rules cannot be absolute--what is? There must be some accommodation of other important values, including the eradication with deliberate speed of the continuing effects of past discrimination.