Incoming Attorney General Benjamin R. Civiletti strongly defended controversial sections of the proposed FBI legislative charter yesterday, as hearings began on the document he said is intended to be the bureau's constitution.

In his first public appearance since being confirmed by the Senate, 94 to 1, Wednesday night, Civiletti tried to show the Senate Judiciary Committee that liberal critics' complaints about the charter were unfounded.

Civil liberties groups and some members of the committee already have expressed concern about provisions in the bill that would expand FBI authority, but contain no specific prohibitions against political spying and no new criminal or civil penalities for charter violations.

Sen. Alan K. Simpson (R.Wyo.) criticized the charter from the opposite direction at yesterday's hearing, saying he had "grave reservations" about the present draft because he feared it might handicap the FBI.

Proponents of the legislation, which would provide the first real statutory authority for the FBI, long have predicted the focus of debate would be whether the charter adequately protects both civil liberties and the bureau's ability to investigate aggresively.

Civiletti said that a ban on COINTELPRO-type spying on political groups doesn't have to be part of the charter because it isn't authorized, and thus, is outside the bureau's jurisdiction.

He also emphasized the need for expanding the FBI's authority to include "investigative demands" for telephone, insurance and credit records. He said he was surprised to learn on joining the Justice Department in 1977 that the FBI did not already have such powers. "I think it's long overdue. I think there are no sound arguments aginst it," he said.

Civiletti noted that many other agencies now have similar administrative subpoena-type authority. And he noted that access to such records would be subject to the same protections, of notice and opportunity to challenge, that are available under a new federal bank records law.

He also said there isn't any need for new enforement powers in the charter because existing laws allow both criminal prosecution and civil suits for violations. In addition, Civiletti said, FBI Director William H. Webster would have authority under the charter to fine his agents up to $5,000 for willful violations of rules governing sensitive investigative techniques such as wiretaps.

Outgoing Attorney General Griffin B. Bell and Webster also testified briefly at the hearing, which Chairman Edward M. Kennedy (D-Mass.) said would be followed by several sessions focusing on specific parts of the bill.

Kennedy and several other members of the committee praised Bell lavishly for his record as attorney general over the past 30 months.

Bell responded, with his usual humor, that the kind words reminded him of the joke about a widow who heard such exaggerated talk at the funeral about her husband's accomplishments that she had her son check the casket to make sure they were burying the right man.

Simpson's criticism of the charter was triggered in part, he said, because the American Civil Liberties Union seemed to have more input on the draft than FBI street agents or Republican senators. He charged that the ACLU is "notorious for its allergic reaction to all forms of law enforcement."

And he complained that the draft had been handed to him as a finished product. Democratic members of the committee have also complained that Kennedy and his staff didn't consult enough with them in preparing the bill. CAPTION: Picture, Civiletti, Bell and Webster, appear at Hili hearing on the controversial new charter for the FBI. By James K. W. Atherton -- The Washington Post