Former attorney general Benjamin R. Civiletti told a Senate subcommittee yesterday that the special prosecutor investigations he recommended of top Carter administration aides Hamilton Jordan and Timothy Kraft were "an enormous waste of public funds," and he suggested amending the special prosecutor law.

Civiletti's successor, William French Smith, has expressed concern about the constitutionality of the law. One of his top aides is expected to tell the subcommittee Friday that the law should be repealed.

Jordan and Kraft were accused of using cocaine, but not charged after lengthy investigations triggered by the special prosecutor provisions of the Ethics in Government Act of 1978.

Civiletti was joined yesterday by Philip B. Heymann, former head of the Justice Department's Criminal Division, and Lloyd N. Cutler, former White House counsel, in recommending changes in the law to prevent recurrences of cases such as those of Jordan and Kraft.

Civiletti and Heymann noted that, under the current law, officials like Kraft and Jordan are treated more harshly than are regular citizens, who in most jurisdictions wouldn't even have been investigated by federal authorities for alleged cocaine use.

The suggested changes include:

Raising the level of evidence needed to trigger the act from the current "specific information" to something approaching probable cause, and confining the allegations to major crimes.

Extending the 90-day period an attorney general has to make a preliminary judgment on the quality of the evidence.

Confining the list of covered officials to those in high-level positions and extending it to cover immediate members of the president's family. Cutler cited the controversy over the handling of the investigation of Billy Carter's dealings with Libya as a reason for adding family members.

Paying the legal fees of accused officials who are not charged after an investigation.

Changing the name of the outside lawyer from special prosecutor to special counsel to remove the Watergate connotation from the public image of the incident under investigation.

Letting the attorney general, rather than a special court, appoint the special prosecutor from a pool selected by a blue-ribbon panel. This would overcome some of the constitutional doubts about the law expressed recently by Attorney General Smith, Cutler said.

Samuel Dash, chief counsel of the Senate Watergate committee, argued against major changes in the law. He defended how it has worked over the past few years, noting it had not "attracted an onslaught of hundreds of charges against presidential aides as had been feared by its opponents."

Sens. William S. Cohen (R-Maine) and Carl Levin (D-Mich.), chairman and ranking minority member, respectively, of the subcommittee on oversight of governmental management, indicated in their questioning that they link the law needs changing. A subcommittee aide said later that amendments probably will be proposed.