As a result of the FBI's Abscam operation, two House members have been convicted. And by the time the rest of the defendants have been tried, Abscam may go into the history books as the most successful investigation of congressional corruption ever accomplished.

But in the glow of the success, disturbing questions remain. There are four areas where the FBI employed tactics that can best be described as dubious, even if they are eventually upheld by the Supreme Court:

--Premature leaks. Last February, long before any indictments were returned -- indeed, before any grand juries had been convened to hear the evidence -- Justice Department and FBI officials leaked to the press the names of the politicians involved, including some who were eventually indicted, some who have not yet been indicted and some who may never be.

Attorney General Benjamin Civiletti acknowledged this violation of the suspects' civil rights, calling the flood of leaks "one of the low points" in Justice Department history. Professing outrage, Civiletti appointed a special investigator, Richard Blumenthal, to find those responsible for this "perversion" of justice.

Blumenthal's report was finished months ago. FBI Director William Webster has said it "points the finger" at certain Justice Department officials. But Civiletti has taken pains to keep the report secret until the Abscam trials are over.

--Entrapment. In an operation like Abscam, there is always the danger that lawmen have set in motion crimes that otherwise would not have been committed. Assistant Attorney General Phil Heymann, who took personal charge of the Abscam investigation, has insisted that no one from the Justice Department "dangled bait in front of a congressman."

But videotapes, reviewed by my associate Gary Cohn, show that on numerous occasions the FBI operatives came perilously close to entrapment. Consider, for example, the case of Sen. Harrison Wiliams (D-N.J.).

The tapes clearly show that the FBI's Abscam "recruiter," convicted con man Mel Weinberg, coached the senator on the best way to act when he met the fictitious "shiek" who supposedly wanted to buy congressional influence.

"You gotta tell him how important you are," Weinberg told Williams, "and you gotta tell him in no uncertain terms: 'Without me, there is no deal . . . I'm the man who's gonna do this and use by influence and I guarantee this.'"

Even some Justice Department lawyers were doubtful about these tactics. One department memo concluded that "congressional violations of due process in the Abscam investigation may have fatally infected the investigations and possible convictions."

--Unethical conduct. The Abscam team resorted to some dubious investigative techniques. Weinberg, for example, suggested to an unwitting middleman, Philadelphia lawyer Howard Criden, that he ply Rep. Frank Thompson (D-N.J.) with booze to get him to take a bribe on camera.

--Unethical conduct. The Abscam team resorted to some dubious investigative techniques. Weinberg, for example, suggested to an unwitting middleman, Philadelphia lawyer Howard Criden, that he ply Rep. Frank Thompson (D-N.J.) with booze to get him to take a bribe on camera.

Initially, Thompson refused an offer of cash. The FBI told Criden to bring him back for a second meeting.

"He told me he won't discuss money," Cirden protested. "Give him another drink," replied Weinberg. Criden eventually got Thompson to return, and the tapes show Criden (though not Thompson) accepting a briefcase containing $50,000.

--Targeting. There is disturbing evidence that certain politicians were singled out as targets, while others were declared off-limits to the undercover agents. Leads were provided by the middlemen that pointed to at least seven members of Congress who were not pursued.

On the other hand, witnesses recall hearing Heymann, the head of the investigation, asking in reference to Rep. Richard Kelly (R-Fla.), "Did we get that troublemaker Kelly?" They did. The congressman was videotaped stuffing greenbacks in his pockets and asking, "Does it show?"

Undercover oeprations like Abscam may be the only way to catch congressmen who are on the take. But the sweet taste of success turns a little sour when the government tramples on individual rights in its pursuit of justice.