D.C. Court of Appeals Chief Judge Theodore R. Newman Jr., the city's highest ranking jurist, was threatened with arrest at a Washington restaruant Monday night when he grabbed a police sergeant's arn after officers had arrested a suspect in a year-old assault case, the sergeant told a reporter yesterday.

Sgt. Harvey Bailey of the 1st Police District, who characterized Newman's actions as bordering on "impeding justice," said he was interviewing the assualt victim at the Pier Seven restaurant in Southwest when Newman approached and "went after the complaintant."

"He was yelling at the guy, pointing his finger at the guy, and calling him names," Bailey said yesterday, adding that Newman repeatedly used foul and abusive language. "He was trying to get to the guy."

Bailey said Newman grabbed his arm, at which point, the sergeant said, he threatened to arrest Newman. The judge then backed off immediately, Bailey said.

Newman strongly challenged the accuracy of Bailey's account yesterday, but declined to provide his own version of the incident. U.S. Attorney Charles F. C. Ruff said his office had interviewed the policemen who were at the scene and determined that no charges would be brought against Newman.

The incident followed the arrest at the restaurant of William Sutton, apparently a friend of Newman, on an assualt charged lodged against him in June of last year. Bailey was interviewing the complaining witness in the assault, John Thornton of Arlington, when Newman alledgedly became involved.

"This man approached," Bailey recalled. "I'd never seen him before. Later he was identified as Judge Newman . . . He called [Thornton] a 'mother-f---'. . . I grabbed his wrist . . . 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.

Bailey said he told Newman: "If you don't get back, I'll lock you up. If you don't get back, I'll arrest you." Bailey said Newman then stepped back.

"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.

"I wouldn't say that he actually made any attempt to physically impede," Bailey said. "He told us who he was [and] he didn't feel the arrest was necessary. He knew well and good it was because it was a felony warrant."

Police records show that Sutton was charged last year with assualt with a dangerous weapon on Thornton in an incident that also occured at the Pier Seven restaurant. Thornton complained to police at the time that Sutton hit him in the head, knocked him to the ground and kicked him, breaking three ribs, the record indicates.

The U.S. attorney's office here dropped the chrage last fall because Sutton had left the country, but it was reinstituted last week, police said, after Thornton notified investigators that he had seen Sutton back in town. The charge was reduced yesterday to simple assault and a trial scheduled for later this month.

Sutton, who told a reported that he is a computer specialist based in Saudi Arabia, maintained in a telephone interview yesterday that he is innocent of the aaualt charge. He confirmed, however, that he and Newman were together at the Pier Seven Monday night.

Sutton said the incident allegedly involving Newman was being blown out of proportion and that the judge was only "trying to tell the arresting officer that I was of outstanding character in the community and I had a right to know why I was arrested."