The FBI owes damages to bureau clerks who accepted low-level jobs expecting to benefit from an FBI policy that would have given them preference over other applicants to be special agents, a federal judge ruled yesterday.

The decision by U.S. District Court Judge Louis F. Oberdorfer could mean thousands of dollars in awards for more than 2,000 clerks who had relied on the preference policy, which was terminated in April 1977.

"Many of these persons would not have accepted clerical positions or maintained employment were it not for their expectation that the program would continue," Oberdorfer said.

Oberdorfer said that clerical workers in effect had a contract with the bureau that was premised on the preference policy.

When the clerks went to the bureau, they relied on the benefits promised through the preference policy. In exchange, Oberdorfer said, "the bureau was rewarded with the services of highly qualified and highly motivated persons willing to serve for a substantial period of time in relatively menial positions, lower in challenge, pay and status" than jobs those same persons could have obtained elsewhere.

In April 1977, the bureau adopted a "new special agent selection system" that eliminated a lenient pass-fail examination standard for clerical workers and also ranked all applicants based on combined test and interview scores, regardless of seniority. The system included an affirmative action program for women and minorities.

The clerical and support personnel, who brought the class action lawsuit against the bureau, argued that the old system of pass-fail exams and seniority guaranted them a "preference" for consideration for jobs as special agents. Oberdorfer agreed that the preference was constitutionally protected property right that could not be taken away by the bureau without compensation. The government is considering whether to appeal Oberdoarfer's decision.

One of the plaintiffs in the case, Adolph Kizas, quit his job as a steelworker in 1973, moved to Washington from Pittsburgh and took a 60 percent pay cut to sign up as a GS-2 clerk with the FBI. Kizas took the clerical job after he learned of the special consideration it offered for a position as special agent, Oberdorfer said.

In 1976, after he earned his college degree at night school, Kizas met the minimum requirements for consideration for special agent and expected to be lined up by seniority with other clerks seeking those jobs. But, in 1977, while Kizas was still under consideration, the policy was terminated.

Oberdorfer's opinion did not specify the amount of damages that should be awarded to clerical and support employes who had relied on the preference policy.

Oberdorfer did suggest, however, that computation of damages include such factors as educational and professional qualifications of the employes at the time they signed up with the FBI, and salaries that could have been earned if they had not taken bureau jobs. A hearing was scheduled for Feb. 29 to discuss damage awards.