The D.C. Court of Appeals yesterday ordered a D.C. Superior Court judge to halt his plans to complete the trial of a murder case in which another judge declared a mistrial.

The order, which had beeb sought by U.S. prosecutors, was issued shortly before Judge Eugene N. Hamilton was to impanel the same jury that had been dismissed when the mistrial was ordered last Thursday and have that jury try to reach a verdict.

The appeals court said Hamilton's planned action "shall be stayed pending further order of this court following the filing by (Hamilton) of an answer" to the government's request.

Hamilton announced from the bench that he had retained an attorney to file his answer. He then continued the matter until 10 a.m. today. By that time, he said, he hopped the Court of Appeals would rule in his favor and he would be able to send the case to the jury for a verdict.

These unusual proceedings crose from a ruling by Judge Nicholas S. Nunzio last Thursday that a mistrial must be declared in the murder trial he was then conducting. He ordered the mistrial because he said the attorneys for two of the three defendants had been ineffective. Nunzio then withdrew from the case.

On Friday, the case was assigned to Judge Hamilton. He reconvened the jury that had been dismissed by Nunzio, satisfied himself that its members could judge the evidence impartially, and indicated he planned to take up the trial where Nunizo had ended it.

Federal prosecutors opposed this plan. In a brief filed with the Court of Appeals they said Hamilton "is without jurisdiction or authority to overrule the judgment and order of Judge Nunzio declaring a mistrial, and thus is without authority or jurisdiction to reconvene the original jury panel and proceed with the trial."

Underlying the legal maneuvers since Friday is the issue of double jeopardy - the constitutional prohibition against trying a defendant twice for the same crime.

Prosecutors told Hamilton they believe double jeopardy is not involved. They said Nunzio's ruling that the defendants had received ineffective assistance of counsel meant that, in effect, there had been no trial at all.

Defense attorneys asserted that their assistance was effectivt and that Nunzio's ruling was unjustified. They therefor contend that their clients would be placed in double jeopardy if a new trial were ordered or even if the old one even if the old one were continued.

For this reason, the defense attorneys also have opposed Judge Hamilton's plan to go forward.

Meanwhile, the defendants remain in D.C. jail. They are Gene Arthur (buster) Braxton, 28; his brother, Calvin Lewis Braxton, 22, and Darbell Lee Washington, 26.

They are accused of second-degree murder in the slashingand stabbing death of James Marshman, 39, a construction worker, outside a bar and grill at 9th and L Streets NW on the night of Oct. 10, 1975.

Gene Braxton is represented by Robert Liotta. Calvin Braxton is represented by Kenneth Trombly. Washington's attirney is O. B. Parker. In ordering the mistrial, Judge Nunzio was critical of Liotta and Parker. Both Liotta and Parker were reappointed to the case by Hamilton.