There's a new, defiant tone these days in the statements and reports coming from the embattled U.S. Commission on Civil Rights. Some commissioners may worry that the public thinks the agency has been cowed by the Reagan administration's efforts to sweep the place clean. But the commission, in fact, has been talking tougher than ever.

In the past year, President Reagan has ousted a longtime commission chairman, tried to nominate an obscure black evangelist to the job, then finally put a black conservative in the post. But in the same year, the commission has issued several major reports contradicting basic administration premises about the role government should play in remedying the effects of discrimination.

A new set of reports on civil rights and education are due out this week, and those familiar with the panel's previous work expect the new round of studies will irritate the Reagan administration once again.

"Somebody has to hold the government's feet to the fire without worrying about political repercussions," said Commissioner Mary Frances Berry, a black lawyer and Ph.D. who has offered a consistent counterpoint to the new chairman, Clarence Pendleton Jr. "We've become aware recently that . . . the anti-discrimination laws we thought were going to be important aren't going to be enforced."

These days even Pendleton, who has backed the administration in opposing affirmative action and busing to achieve desegregation, is working toward a rapprochement with his colleagues. His tone is more conciliatory; he now makes it clear in his speeches and interviews that his views don't necessarily reflect the view of the commission, on which he is consistently outvoted. When he runs commission meetings, he makes no attempt to squelch his opponents. And he quickly backed away from a veiled threat to fire state advisory chairmen who sent the president a letter protesting the administration's civil rights policies.

"We have to be a watchdog," Pendleton said in a recent interview. "We still have to be an advocate of equal opportunity and nondiscriminatory policy and when we see issues arise, we need to say that."

Even if it means criticizing the administration?

"The criticisms made when the commission released a report two weeks ago showing persistent high unemployment and underemployment among women and minorities were unfair."

Whatever mellowing has occurred in the commissioners' attitudes toward each other, however, has not eased the tension between the commission and the administration. Current battles over the agency's membership, budget and its future are expected to continue. For instance:

The Office of Management and Budget has proposed cutting the agency's budget back to $10.8 million in fiscal 1984 -- $2.3 million below what the commissioners reportedly requested and 7 percent below the lowest of the proposed budgets for fiscal 1983, a budget that is still in limbo.

Before the election recess, the Senate sent back three of Reagan's nominations for the commission. Senate staffers say it's unlikely that the nominees--including a Milwaukee attorney who called for the abolition of the commission in 1978 -- would be sent back during the current lame-duck session, but are not sure whether the same slate of candidates will be proposed next year.

The commission, up for reauthorization next year, has asked the White House to propose a 15-year renewal instead of another five years. Pendleton is urging the president to back proposals giving commissioners fixed, staggered six-year terms to avoid any wholesale turnover in membership in the future.

The debate over the nominees was bitter this year, in large part because of an unprecedented effort by Reagan to replace six of the seven commissioners in a single year. While all commissioners serve open-ended terms at the president's pleasure, only one other president has ever ousted a commissioner before he chose to retire. In 1972, Richard M. Nixon forced the retirement of commission chairman Theodore M. Hesburgh.

"From the beginning, the idea was to have it function as an independent bipartisan commission," said former chairman Arthur M. Flemming, who witnessed the discussions that led to the commission's creation in 1957. To replace most of the commissioners involuntarily "tends to politicize the commission," Flemming said.

"If the commission is to serve as the conscience of the nation the commissioners must do so without the worrying about reprisal from a president," added Commissioner Murray Saltzman, a Democratic member since the Ford years whom Reagan wants to replace.

"The president showed a good deal of courage in selecting people . . . to look at things objectively," counters Randal Rader, Republican counsel to the Constitution subcommittee of the Senate Judiciary Committee. "The insiders are saying, 'Don't change things because we like it the way it is.' But the way it is is not necessarily the way it ought to be. Do you really want people who have an interest in the outcome of a study doing the study?"

The commission's studies are the thing that give substance to the agency's symbolism. Its reports and recommendations constitute the bulk of the commission's work -- and its most potent public relations weapon. Reagan administration actions produce such headlines as "U.S. Won't Pursue Class-Action Cases Against Job Bias;" subsequent commission reports produce headlines that are almost a retort: "Panel Finds Persistent Bias in Hiring."

"It's been our ability to say what we believe that has created a trust in the commission," said acting staff director John Hope III. "Members of Congress may not agree with us but they don't think we're just another advocacy group . . . . We're the only civil rights research organization in the federal government."