In April 1977, D.C. Superior Court Judge Nicholas S. Nunzio abruptly declared a mistrial in the case of three men accused of murdering a construction worker during an argument outside a Northwest Washington bar and grill.

Nuzio charged that two of the defense lawyers, with whom he had argued for days, had failed to represent their clients effectively and had "exhausted the patience" of the court. Then he fired the two attorneys and banned them from his courtroom.

Yesterday, the D.C. Court of Appeals - in a lengthy opinion filled with criticisms of Nunzio's conduct - barred further prosecution of the three men on the murder charges.

It was Nunzio's exasperation with the case, not the lawyers' conduct or their own earlier requests for a mistrial, that had prompted the judge to stop the trial, the appeals court said.

The decision, written by Judge Frank Q. Nebeker, is the third time in the past four months that the high court has examined Nunzio's trial conduct and then concluded that it had adversely affected the proceedings in his courtroom. Chief Judge Theodore R. Newman Jr. and Judge Julia Cooper Mack concurred in Nebeker's ruling.

After reviewing the opinion yesterday.Nunzio agreed there was "some language" to suggest that the appeals court was criticizing his conduct. But while earlier appeals court opinions, Nunzio said, had directly attacked his judicial performance, he felt yesterday's ruling reflected an honest difference of opinion on legal questions.

Nunzio said he regrets that he did not state more clearly - for the court record - his reasons for declaring the mistrial.

Yesterday's decision came in the case of Gene A. Braxton, Calvin L. Braxton and Darnell L. Washington, all charged with second-degree murder. The three were represented in court by attorneys Robert Case Liotta, Kenneth M. Trombly and O. B. Parker.

In his opinion, Judge Nebeker cited several portions of the trial transcript to show what he characterized as the "escalating antagonism" between Nunzio and the defense attorneys, particularly Liotta.

The effect of Nunzio's efforts to correct the attorneys' conduct indeed exhausted his patience, Nebeker wrote.

Nunzio's objections to their questions "bordered on the trivial," according to the opinion, which also criticized Nunzio for attempting to examine witnesses himself and for "questionable" rulings during the three-day trial.

It was the judge's "exhaustion," Nebeker said, that led Nunzio to accuse attorney Parker of unethical conduct because he had not reported to the court that his client had changed his story. The trial record was "barren" of any evidence of wrongdoing on Parker's part, the appeals court said.

"And this exhaustion, more than any other factor, appears to be the motivating factor for the declarations of the mistrials."

While the trial judge's principle role at trial is to act as an "umpire," the judge often must assume the role of "diciplinarian," Nebeker wrote. When he two roles become confused, he continued, the fairness of a trial can be affected.

The defense attorneys' conduct may have been "imperfect," Nebeker conceded, but it was not "in any sense out of the ordinary."

"Rather it is the case of ordinary failings escalationg, before in jury, into a confrontation betweeen counsel and the trial judge in disregard for the rights of the (defendants) in their confrontation with society," Nebeker wrote.

The appeals court said that all three defense attorneys were "well-prepared" and "zealous" in the representation of their clients. Nunzio had described Liotta and Parker as ineffective.

Following Nunzio's ruling, the three lawyers had argued before another Superior Court judge, Eugene N. Hamilton, that a second trial would subject their clients to double jeopardy. The government, to overcome this argument, had to show that the mistrial had been declared at the defense's request or because there was a "manifest necessity" to do so.