For the past decade or so, courts have been hearing cases challenging civil service tests that are alleged to be discriminatory. Some of the more interesting cases involved the hiring of police and firefighters, because the tests for these much-competed-for jobs were said to measortant to the jobs themselves. In New York, for example, the physical test given to prospective firefighters was found to discriminate against women because it required strength and endurance not necessary to the work. In this city, too, there has been litigation over the written tests given for jobs in the police and fire departments. In most of these cases the issue comes down to this: is a test that women and minorities do not pass in rough proportion to their numbers in the relevant job pool necessarily a discriminatory test?

This week, the Supreme Court decided not to accept a California case involving such a question. The court's action leaves in place an appellate ruling that the Los Angeles exam for firefighters is a valid one. The case has a long history -- not unlike others around the country -- and shows not only that hard work, good will and court pressure can produce an unbiased hiring system, but that at some point a reasonable solution will be accepted by the courts.

The Los Angeles case began in 1969 when the county voluntarily abandoned its existing written and physical tests because they discriminated against blacks and Hispanics. In the early '70s, these minorities constituted 29.1 percent of the county's population but only 3.3 percent of the firefighters. Over the next 10 years, a number of steps were taken: minorities were recruited widely and prepared for the exams; hiring plans in 57 counties and 44 cities were studied for models; pass-fail exams with random selection without regard to rank were adopted; court-ordered plans requiring that two of every five recruits be minorities were put into practice.

In 1979, the current plan, which included a written exam worth 25 percent and an interview worth 75 percent, was established. Though it has resulted in an 18 percent selection rate for minorities, the appellate court found the test to be a fair one that accurately assessed skills needed on the job. Los Angeles officials are pleased that after lengthy trial and error, their hiring plan has been approved by the courts. And even the lawyer for the losing plaintiffs -- who says he will continue to monitor hiring procedures -- concedes that the county has come a long way. The objective of achieving nondiscriminatory job policies has been worth all the efforts of Los Angeles County and its minority community. Other cities look with hope at their success.