Another of President Reagan's nominees has run into trouble on Capitol Hill, this time over statements on the administration's approach to age discrimination.

Jeffrey I. Zuckerman, nominated as general counsel of the Equal Employment Opportunity Commission, came under sharp questioning at a Senate hearing last month when he challenged a series of court rulings on age discrimination. He is expected to be questioned extensively when his confirmation hearings resume.

In some cases, Zuckerman said, companies legally may dismiss workers based on their eligibility for retirement benefits, although three federal appeals courts have held that this approach is so closely related to age that it constitutes age discrimination.

Zuckerman, 35, now chief of staff for EEOC Chairman Clarence Thomas, said he simply was explaining that the commission must continually reexamine its policies. But Sen. Howard M. Metzenbaum (D-Ohio) accused him of selectively interpreting the law and trying to reverse a longstanding EEOC policy.

Civil rights activists and senior-citizens' groups are carefully watching the nomination as a barometer of changing EEOC policies. Many have said that they view Zuckerman as a staunch conservative who would hasten the commission's shift to the right and press the kind of policies favored by William Bradford Reynolds, assistant attorney general for civil rights.

Zuckerman was a special assistant in the Justice Department's antitrust division before joining the EEOC 16 months ago.

The graying of the work force has made age bias cases, covering workers from 40 to 70, a growing part of the commission's workload.

Zuckerman's nomination comes as the EEOC is moving away from broad complaints against big companies and entire industries in favor of more tightly focused cases involving specific persons. It also follows a sharp reversal of the panel's position on affirmative-action hiring plans.

In a 1983 court case involving New York sheet metal workers, the EEOC supported use of minority hiring goals and timetables, which Reynolds opposes as a form of racial quotas. When the case was appealed to the Supreme Court last year, however, the EEOC changed positions and joined the Justice Department in a legal brief opposing goals and timetables as illegal quotas.

"I agree with the approach taken by the commission in that case," Zuckerman said in an interview. "I would not support quotas as a remedy."

He said employers are free to use goals and timetables for minority hiring "as long as the company doesn't use it as a means or subterfuge for discrimination."

Zuckerman said the EEOC is sending a message to employers with its new policy of going to court on every legitimate complaint.

"What we mean to do is seriously to enforce the laws, wherever and whenever discrimination occurs," he said. "That is a radical change from the past . . . . We will sue on behalf of one person; we will sue on behalf of 100,000 people."

Barry L. Goldstein of the NAACP Legal Defense Fund said that the EEOC's enforcement effort sagged badly during Reagan's first term. But he said it was not until 1984 that "the commission retreated from a defense of affirmative action."

"The EEOC has signed onto a brief that attacks the very type of affirmative action which the commission has encouraged employers to undertake in its own guidelines," Goldstein said. "It appears now that the EEOC is at a critical fork in the road. It is important that Mr. Zuckerman be carefully questioned as to whether he will support a broad application of the civil rights laws."

The general counsel is a presidential appointee who is supposed to act as a check on the EEOC chairman. The previous general counsel, David L. Slate, resigned in 1984 with a bitter blast at Thomas for narrowing the agency's focus.

According to administration sources, Thomas had told associates that he wanted the job to go to acting general counsel Johnny J. Butler, a career employe and political moderate who once worked for the NAACP Legal Defense Fund. But the sources said that White House officials decided to nominate Zuckerman, instead.

At a hearing before the Senate Labor and Human Resources Committee Dec. 10, Metzenbaum charged that Zuckerman was ignoring court rulings he disagrees with. Opponents used the same allegation to defeat Reynolds' nomination as associate attorney general last June.

Zuckerman was questioned about a 1984 memorandum in which he told Thomas that it was "reasonable" for a company making layoffs to dismiss employes who would receive retirement benefits. If that was the case, he wrote, the commission should not pursue a proposed lawsuit against an unidentified company.

Zuckerman wrote in the memo: "It seems to me that eligibility for retirement is a reasonable factor other than age . . . . It seems to me reasonable for a company that must lay off employes to do so in a way that minimizes the economic hardship upon those laid off, by discharging first those who will receive retirement benefits."

"You are obviously pretty smart," Metzenbaum said. " . . . How could you make such a recommendation when three federal courts of appeals had issued four separate decisions . . . holding it was unlawful age discrimination to treat employes differently based upon their eligibility for retirement?"

Metzenbaum questioned why Zuckerman had not advised Thomas of the previous court rulings, asking: "You think that what 'seems to you,' which is the phrase that you used twice, is more important than telling the chairman of the commission what the law is?"

Zuckerman said that other aides had already given Thomas the legal background and that he was trying to provide "some additional insight." Asked why he was challenging EEOC's previous policy, Zuckerman replied:

"To the extent that it may come to the conclusion that it has taken a wrong position in the past . . . then the commission can change its position."

"Even if the courts have said what the law is, the commission should change its position?" Metzenbaum asked.

"It depends what courts," Zuckerman said. "It depends . . . . "

"Oh, now tell me about that," Metzenbaum shot back. "Tell me which courts you like and which ones you don't like."

Zuckerman replied that circuit-court rulings apply only in a particular circuit and sometimes conflict. But he acknowledged that no other appeals court has ruled differently on the issue.

"I just think you are so far off the wall on this point, legally . . . . I am absolutely shocked by your testimony," Metzenbaum said.

Questioned by Sen. Christopher J. Dodd (D-Conn.), Zuckerman also said he had "serious reservations" about a related EEOC policy on age discrimination that says employer actions having an "adverse impact" on older workers should be construed as age discrimination, regardless of their intent.