The D.C. Judicial Tenure Commission that is responsible for investigating misconduct of local judges has begun an inquiry into allegations that D.C. Court of Appeals Chief Judge Theodore R. Newman Jr. improperly intervened in the arrest of a criminal suspect at a Southwest Washington restaurant last summer.

D.C. police Sgt.Harvey Bailey has alleged in a published interview that Newman, the highest-ranking city judge in Washington, took action that bordered on "impeding justice" as police were interviewing a complaining witness after making an arrest at the Pier Seven restaurant.

Sgt. Bailey is one of several police officers and other officials who have been interviewed in recent days by the D.C. Commission on Judicial Disabilities and Tenure. The seven-member commission, whose members are appointed by the president, the mayor, the City Council, the D.C. Bar, and the chief judge of the U.S. District Court here, has the power to discipline, reprimand or remove a judge from the bench.

The tenure commission's decision to look into the Pier Seven incident is believed by some of Newman's supporters in the Washington legal community to be an attempt to embarrass the chief judge. Some of his supporters believe Newmman has been particularly vulnerable since four of his colleagues attempted last fall to dislodge him as chief judge of the nine-member court. It could not be learned whether the commission has interviewed Newman, whether the commission initiated the probe on its own, or acted after a formal complaint on the incident.

It also could not be determined last week how serious the commission considered the allegations against Newman and all commission officials contacted declined to comment, noting that all investigations are conducted confidentially.

Among others who have been interviewed by the commission, sources said, were U.S. Attorney Charles F.C. Ruff, whose office conducted its own investigation of the matter, other officials of the U.S. attorney's office, and police officer Daryl M. Williams, who also was at the scene of the alleged incident. Ruff, whose office brought no charges against Newman, has provided the commission with the results of his investigation. Ruff declined to comment yesterday.

According to Bailey's account, he and several other police officers arrived at the Pier Seven restaurant on July 6 where they arrested William Sutton, a Southeast Washington man who had previously been charged with assault. As Bailey interviewed the complaining witness in the case, John Thornton of Arlington, at the restaurant, the chief judge approached, Bailey alleged, and "went after Thornton ."

Judge Newman repeatedly used abusive language and at one point grabbed the sergeant's arm, Bailey alleged. "If you don't get back, I'll lock you up. If you don't get back, I'll arrest you," Bailey recalls saying.

Newman "categorically" denied Bailey's allegations in an internal court memorandum dated July 8, which was circulated to the other judges of the Appeals Court. "Rest assured I did nothing on the occasion of Monday evening to bring this court or my office in any manner into disrepute," the memo said. Newman also accused Bailey of a "blatant, absolute lie" in a press interview at the time. Reached this week, Newman declined to comment on the commission investigation.

In an apparently unrelated inquiry, the commission also has asked the Court of Appeals to provide it with tape recordings of several oral arguments in court cases that were heard before Newman on four different dates in June and July of this year. The reason for that request could not be determined.

In the incident at the Pier Seven restaurant at 650 Water St. SW, Bailey has alleged that Newman called the complaining witness, Thornton, "a 'mother-f-----' . . . I grabbed his Newman's wrist," Bailey recalled. "I told him to get back. I told him I was talking to this man, wanted to escort him outside. He Newman was getting more aggressive."

Bailey said he then told Newman that he would arrest him if he did not step back, and Newman retreated.

"As I was dragging [Thornton] out," Bailey recalled, "the judge was yelling at him. He appeared to be very angry at the complainant . . . He said, 'You're a common, no-good mother-f-----' . . . I do remember those words over and over and over."

Another officer at the scene, Daryl M. Williams, confirmed yesterday that he had been interviewed by the commission, and repeated again that Newman was "really being disorderly . . . I didn't find out till the next day that he was a judge."

Sutton has since pleaded guilty to a charge of simple assault, according to court records.