The government yesterday urged a D.C. Superior Court judge to deny a new trial for 12 Hanafi Muslims convicted of the siege of three Washington buildings, arguing that there are insufficient grounds to investigate defense claims that one of the jurors may have been mentally unstable during the trial.

Attorneys for the Hanafis had claimed in court papers that the juror was barricaded in a bathroom for an undetermined amount of time during jury deliberations. They also claimed that after the trial was completed, and the verdict delivered, the juror may have set fire to her apartment, became confused and disoriented, and was subsequently taken to St. Elizabeths Hospital for observation.

They asked Superior Court Judge Nicholas S. Nunzio to hold a closed hearing to inquire into the woman's "ability to function as a rational juror." Based on information that maight be revealed at the hearing, the lawyers asked Nunzio to grant a new trial for the defendants, who were convicted last July.

In its response yesterday, the government argued that the defense lawyers' contentions do not even warrant "the holding of an evidentiary hearing much less the granting of a new trial."

The government maintains that the courts have established that such an investigation would be appropriate only if the juror had been found mentally or physically incompetent by a court prior to or shortly after the verdict was returned.

In the Hanafi case, no evidence has been offered that the juror whose conduct has been questioned was ever declared incompetent, the government argued, and therefore, a hearing into her competency during the trial is not warranted.

Furthermore, the government said, Judge Nunzio can properly take into account his own observations of the juror's conduct in deciding questions about her competency. The government described the woman as responsive to questions during jury selection, "neat and attentive," and said her courtroom conduct was "exemplary."

The government denied the defense attorneys' claims that the prosecutors had knowledge that the juror had allegedly "barricaded" herself in a bathroom during deliberations.

Defense lawyers claimed that deliberations in the case may have continued during the juror's absence, thus depriving their clients of a trial by 12 jurors. The government, however, said in court papers that there is no evidence to support the claims that the woman actually "barricaded" herself in the bathroom. At most, she may have locked the door, which is not unreasonable, the government said.

"To grant a new trial on this ground or even to hold an evidentiary hearing would constitute a travesty or justice," the government said.

The government also noted a recent decision by the D.C. Court of Appeals that upheld a conviction, even though a juror was absent from the jury room for about 90 minutes. In the Hanafi case, the government noted, the juror "merely used a bathroom . . . intended for her use during deliberations."

The entire jury was alert and attentive during the trial, the government said, "and they are proof positive that the American system of trial by jury is truly the best system in the world.

"They should be left in peace and not subjected to harassement," the government said in asking the judge to deny the defense requests for a hearing and for a new trial.