Even critics call him a "lawyer's lawyer," and that is the legacy that Michael Sohn, the Federal Trade Commission's chief general counsel, leaves behind as he moves back from the agency to his prestigious partnership at Arnold & Porter, the powerful Washington law firm.

Sohn left the FTC last week, after 2 1/2 years as the controversial agency's attorney. He was the FTC's lawyer in fights that left the agency's fate not in the hands of a court but, instead, in the hands of a Congress that was eagerly hoping to tie the hands of a commission that had become the scourge of the business community it regulates.

Friends say he had a major role in preventing the agency from going down the tubes. Critics, including powerful people on Capitol Hill, say his unwillingness to compromise and his failure to view the FTC's predicament as a tough political as well as legal problem, endangered the survival of an effective FTC.

"He drove me nuts," said one source close to the congressional negotiating process. "Every time we'd turn around, he'd say this or that is below the White House bottom line. He was very strident. He'd constantly say Congress was selling out the public interest, trying to set a high moral tone.

"In a perfect world, the guy would be right. He's a brilliant lawyer, but a lousy lobbyist. He wouldn't count votes. A couple of times if we had followed his advice, the FTC would have really been in serious trouble."

Sohn responds by saying that when the fight for the FTC was its most critical point, there was warfare on several fronts simultaneously. He and the other two members of the key FTC congressional leadership team -- Chairman Michael Pertschuk and legislative counsel William Baer -- had to watchout for the possible demise of eight major cases and potentially crippling changes in FTC operations in another half dozen areas.

"We had to fight for all of them," Sohn said this week. "Strategically, it would have been a mistake to say what we would settle for. You would have had a credibility problem and it was very important not to have those signals go out prematurely. Those would have become your floor positions."

Another source close to the FTC situation sees Sohn's reception from some quarters as the predictable result of Sohn's "style of vigorous advocacy. He definitely thought of himself as a lawyer for a client, forced to subordinate his own views to whatever he thought the mandate is," said the source.

Yet even Sohn's political foes, noting that the FTC negotiations were characterized by unusual personal animosities among the parties, say he did not play the game that way.

One said that after he and Sohn had a "blistering" telephone coversation, two called each other seconds later. "He put a lot of pressure on but it never became ugly and personal," said the source.

In character, Sohn leaves the FTC with little fanfare, unlike the clamor that accompanied the departure of Alfred Dougherty, the director of the FTC's Bureau of Competition. Amid much controversy, Dougherty also left the commission last week, charging in a resignation letter that he doubted the commission would take on tough cases, thereby undermining staff morale.

"I understand why he expressed that concern," Sohn said. "But I don't see the commission shrinking from aggressive enforcement action when appropriate."

Sohn, 37, is returning to the big money, high-powered world of Arnold & Porter, having worked at the FTC since May 1977. He pledged to stay with the agency for only two years, but that plan went out the window when it became clear that a bitter fight was ahead in Congress.

He had come to the FTC, after developing a reputation as a tough private attorney, handling work before the agencies, in addition to civil cases.

Yet Sohn did not anticipate the congressional storm when he took the commission job. "We did not know then the extent to which there would be this political appeal against regulation," Sohn recalled.

He blames much of the controversy on the spate of rule making that surfaced during the Pertschuk regime, regulations involving parties as diverse and powerful as the funeral and used car industries. Those proceedings emanated from the so-called Magnuson-Moss Act, the six-year-old legislation that gave the FTC the power to issue industrywide rules.

Close to 20 rules were launched at the same time under the "perception here that that was what the Congress wanted the FTC to do." Yet, he also admits that the FTC itself brought on some of the flap, citing inadequate staff work.

"It is true that there had been some rhetoric and speeches that in retrospect proved to communicate a sense of combativeness and antibusiness spirit that alienated people," Sohn said."Those were mistakes. The perception was understandable, but it was not the reality."

In the end, however, the FTC that Sohn and Dougherty left is by all accounts a damaged agency, if not so much in the pure legal sense. Sohn was, by all accounts, vital in helping to clean up language in the report on the FTC bill that could have made the FTC's work difficult for years.

In the view of Sohn and other key officials, no major FTC cases were gutted on Capitol Hill, although that prospect had appeared likely as the agency's opponents sought to kill controversial FTC work in fields as diverse as advertising for children and agricultural cooperatives.

But support did not really even materialize until Attorney General Benjamin Civiletti, prompted by a query involving another agency, said in late April that the FTC would have to shut its doors on May 1 -- the end of its full funding -- unless Congress acted. After a brief shutdown, the agency was brought back to life.

Yet, despite the support that emerged in April, Sohn worries about the virtually unprecendented tactics used by the lobbying and legal communities in coming to Congress to end ongoing FTC investigations and pending cases.

"Attempts to get Congress to intervene in pending cases undermines the administrative process," Sohn said. "That is the more serious threat. A process which ought to be immune from that kind of pressure is in serious jeopardy. When you're dealing with antitrust cases on the floor, that is an impossible call for a congressman to make. That's what the court of appeals is for.

"You can expect those tactics to continue," he said. "Certain elements of the business community will attempt to continue to pressure Congress to intervene in agency proceedings. I'm less clear on how the Hill will react to that. I think it would be hard for a lawyer not to do that, but only Congress can make it clear that that's not an avenue that is open.

"I personally would be loathe to do that," Sohn added. "But I guess I'm pretty old-fashioned."