The director of a national association of public defenders has demanded an apology from Maryland attorney general Stephen H. Sachs for his use of an undercover agent in an investigation of Anne Arundel County public defender T. Joseph Touhey.

Howard B. Eisenberg, director of the defender division of the National Legal Aid and Defender Association, a 9,000-member organization of lawyers who represent the nation's poor, said Sachs' move to gain information with an infiltrator on alleged improprieties in Touhey's office "seriously compromised" public confidence in the defender system.

Eisenberg told Sachs in an Aug. 28 letter that he was "particularly offended" by the attorney general's use of an infiltrator, a move he said amounted to "a gross violation of the adversary process" in the criminal justice system.

Eisenberg and several local public defenders contend that confidential attorney-client relationships between public defenders here and seven indigent crime suspects were violated when Sachs hired a law student to volunteer his services to Touhey as a law clerk last March.

The bogus law clerk, Naval Academy instructor and law student Lt. Cmdr. Steven Vanderbosch, was ordered by Sachs to gather information on Touhey's alleged misuses of his public defender secretarial facilities. Vanderbosch then reported his findings to Sachs' office, a move that led to a grand jury investigation of Touhey's office.

Deputy attorney general George Nilson today defended the move to use Lt. Cmdr. Vanderbosch as an undercover agent and said he is confident Sachs has "no intention of apologizing to anyone for the technique used to investigate Touhey." Sachs is vacationing and was unavailable for comment today.

Nilson said "every step was taken" to assure that no information on defense cases was passed from Vanderbosch to anyone during the law student's three-week stay in Touhey's office. A directive was issued to Vanderbosch to that effect, Nilsen said. He added that, "it was totally adhered to" by Vanderbosch.

After a county grand jury decided last week to terminate its investigation of Touhey without an indictment, the attorney general's office announced it had filed a civil suit here seeking to recover $63,622 in damages from the Anne Arundel public defender. The suit alleges Touhey used his public defender secretary to process paperwork for his private law practice.

Touhey has expressed confidence that the attorney general's office will fare no better with the civil charges filed against him than it did in his quest for a criminal indictment.

"I'll give Sachs every opportunity and every reason to drop the civil charges. If he insists on pursuing the matter, he'll come out of this with a lot of egg on his face," Touhey said in a recent interview.