The continuing legal sparring match between Lt. Col. Oliver L. North and the congressional committees investigating the Iran-contra affair entered a new arena yesterday as North's lawyer protested vehemently that the proceedings were unfair to his client, and Senate Committee Chairman Daniel K. Inouye (D-Hawaii) repeatedly overruled his objections.

For months, Brendan V. Sullivan Jr., North's lawyer, had been jousting with committee lawyers over whether his client would testify and negotiating conditions, from the scope of private questioning to the timing and duration of North's public appearance.

Yesterday, the battle continued as Sullivan asserted that, despite a grant of immunity, North's constitutional rights were being violated by his being forced to testify. North's team of lawyers, he said, had been unable to review "massive quantities of documents" provided to them last week and had no chance to examine notebooks of tape transcripts, memoranda and other documents being used in the questioning by House chief counsel John W. Nields Jr.

Sullivan accused the committees of working "hand in glove" with independent counsel Lawrence E. Walsh. "As a defense lawyer," he said, "I have never been in a position where a client is forced to testify about all matters which are the subject of a pending indictment."

Inouye dismissed the complaints, countering that Sullivan had urged the committees to move up North's appearance, to allow the exchange of documents shortly before testimony and to limit private questioning.

North's request that he be permitted to make an opening statement yesterday despite congressional rules requiring that such statements be filed 48 hours in advance, Inouye said, was just another example of North suggesting "that he may be above the law." Inouye said North could make his statement Thursday morning.

The disputes pointed up the vast differences between appearing before congressional investigators and facing criminal charges in court.

There are rules to cover almost every aspect of a court proceeding, from what documents must be supplied to the defendant, and how far in advance, to what evidence may or may not be used at trial. There is little such prescribed procedure in a a congressional investigation.

"There aren't any rules," and the presiding officer, filling the role of the judge in ruling on objections, "is also someone who has an interest and a stake in the hearing," said Stanley M. Brand, a former House general counsel who now represents many individuals summoned to appear before congressional committees.

"It's pretty wide open," he said. "Objections are more limited, hearsay and all kinds of evidence that might be inadmissable in a court is admissable in Congress."

For example, at one point yesterday, Nields was questioning North about notes taken by an aide to Attorney General Edwin Meese III during an interview with North.

"Objection," Sullivan interposed. "You're reading from someone else's notes. . . . I don't know whether they're accurate. I don't know whether they were rewritten for the occasion here today, and it's not appropriate to question a witness about someone else's notes."

"For the purposes of a congressional inquiry, the question is proper," Inouye responded. "Objection is overruled."

"It looks like a court but it isn't a court," said Georgetown law Professor Paul Rothstein. "The biggest difference from a court proceeding is that broad conclusions, argumentative things, assertions of moral indignation are made from the podium."

The difference, he said, is largely a result of different functions.

"The purpose of the committee is to gather information for oversight and legislation, whereas a court is adjudicating people's rights and adjudicating guilt or innocence," Brand said.

For lawyers representing clients in such proceedings, the experience can be daunting.

"The key fact is that the rules of evidence don't apply, and the presiding officer is basically a political figure rather than a judge," said Philip A. Lacovara, a former counsel to the Watergate special prosecutor who is now in private practice here.

"It's like going into a jury trial where the jurors have their minds made up and are permitted to ask questions," said Plato Cacheris, the lawyer for Fawn Hall, North's secretary, who testified before the committees last month. "It's not a legal proceeding in the sense of a trial in any sense of the word," he said. "They're two different animals. . . . You're not in the structured rules that you are in a courtroom. Here, everything goes."

Because Walsh had already granted Hall immunity from prosecution before her congressional testimony, Cacheris said, "I wasn't thinking of another front. North has that problem certainly more than I do. The independent counsel has not given North immunity and he's got to have his eye down the street."

The committees have granted North so-called "use immunity" for his testimony before it, meaning that Walsh may not use North's testimony -- or any leads derived from it -- against him. That immunity, however, does not protect North from being prosecuted with evidence gathered independently or from being charged with perjury if Walsh determines that he lied in his testimony before the committees.

For Sullivan, one "fairly important" advantage over a court appearance, according to Lacovara, is his ability to "sit at his client's elbow" and advise him during the questioning.

"He could be doing any one of a number of things -- suggesting an answer, alerting the witness to what the next question is likely to be," Lacovara said. "The lawyer has got a lot more control . . . over the pace at which his client answers questions and the answers he gives."