When Brian Lederer was ousted as D.C. people's counsel by Mayor Marion Barry late last year, a lot of people assumed that Lederer's replacement, Frederick Dorsey, would be a more compliant "team player."

But Dorsey vowed he would continue Lederer's practice of aggressively advocating the public interest at utility rate hearings. And during the past week, he has proven himself to be a tough-minded, independent administrator.

At issue was Barry's controversial decision to veto a bill giving the people's counsel more authority to spend money in fighting proposed utility rate increases before the D.C. Public Service Commission.

Until recently, Barry had indicated he would support the measure. But under pressure from PSC members, who were displeased with a section restricting the activities of the PSC staff, Barry changed his mind and vetoed the bill last Friday.

Some of the mayor's critics charged that Barry had seized on a relatively minor point as an excuse for killing the entire bill and jeopardizing the continued effectiveness of the people's counsel.

The City Council voted 11 to 1 this week to override the veto, thus enacting the law. Dorsey's statement expressing "grave disappointment" with the veto and pooh-poohing the mayor's rationale provided ample ammunition to council members who opposed Barry on this key issue.

"The impact of this veto on all consumers everywhere cannot be overstated," Dorsey said. "I deeply regret that the mayor has been so poorly advised on this matter . . . The last-minute lobbying that resulted in this veto was unfortunate."

Strong words from a man who some thought would be the patsy of the administration.

Dorsey, a former principal deputy in the D.C. corporation counsel's office, took over from Lederer Jan. 13 after winning confirmation from the City Council. He was opposed by a number of local consumer groups that expressed concern about how forceful he would be in representing the people in utility rate cases.

Dorsey promised to continue "the same kind of forward thinking" that has been characteristic of the office of the people's counsel.

It didn't take him long to learn about the pressures that dogged Lederer for years.

Lederer, a lawyer who was first appointed to the people's counsel post in 1977, gained the respect of many consumer groups with an aggressive, albeit expensive, approach to challenging proposals for major utility rate increases.

It was no secret that many utility executives, including the mayor's friend Delano E. Lewis of Chesapeake & Potomac Telephone Co., considered Lederer a thorn in their side and wanted to get rid of him.

Lederer had enjoyed substantial support among elected officials and community groups for years, but in more recent times his base of support had begun to erode.

Lederer's alliance with City Council member Betty Ann Kane, chairman of the Public Service and Cable Television Committee and a longtime critic of the mayor, cost Lederer some crucial support within the administration and among other council members who are not fond of the outspoken Kane.

Some council members also bought the utility company's argument that Lederer had been extravagant in hiring outside counsel and experts to prepare testimony in rate cases before the PSC.

Those costs were assessed against the utilities and in turn passed along to consumers.

So when Lederer's latest three-year term was about to expire, Barry announced that it was time for some "new blood" and that he had nominated Dorsey as the new people's counsel. Clearly, the transfusion did more for the patient than the mayor anticipated.