The U.S. Court of Appeals has given the judge in the trial of D.C. Mayor Marion Barry until this afternoon to reply to the American Civil Liberties Union's appeal of his decision barring Nation of Islam leader Louis Farrakhan and Bishop George Augustus Stallings Jr. from the trial.

The ACLU, which filed the appeal on behalf of Barry and the two controversial black religious leaders, alleged that U.S. District Judge Thomas Penfield Jackson's rulings last week -- in which he called both men potentially disruptive and intimidating to jurors -- were unconstitutional and "unsupported by any evidence whatsoever."

The court has given the ACLU until noon tomorrow to respond to Jackson's arguments. The timetable indicates that the case is on the fast track the ACLU sought.

Jackson continued yesterday to draw fire for his decision.

Del. Walter E. Fauntroy (D-D.C.) attended the Barry trial for the first time, saying he had come "on a matter of principle." Jackson, he said, "was in error denying any citizen access to a public trial on the basis of the judge's perception of that citizen's views."

A few blocks from the courthouse, at a rally for the mayor, some supporters held posters aloft that read, "Jackson, Why Don't You Open That Door?" and "Judge Jackson: If Farrakhan is 'Disruptive and Intimidating' Prove It."

Meanwhile, the legal community debated whether Jackson, by barring two high-profile figures from his courtroom, had exceeded a federal judge's broad discretion to assure the integrity of trials and bar someone who disrupts proceedings.

Several experts said Jackson had gone too far by acting without a hearing to determine whether they would do anything disruptive.

Constitutional law expert Bruce Fein likened it to the trial in "Alice in Wonderland."

"If ever there was the epitome of the Queen of Hearts, this is it," Fein said. "Sentence first, verdict later . . . . This is the epitome of judicial arbitrariness."

Others said they could envision circumstances where extraneous and inappropriate passions of jurors could be aroused by the appearance of a well-known spectator, and a judge would be well within his authority to exclude that individual.

Former federal judge Marvin Frankel of New York, noting that he was commenting generally, said a spectator who is "an electric or charged figure" might trigger that situation.

"I can see where a judge in the exercise of his broad powers to keep a trial on an even keel might say, 'I simply won't allow this leader of the Ku Klux Klan, or this inflammatory politician or this sexy woman to come into my courtroom,' " said Frankel. "I can see that being upheld."

Farrakhan, the leader of the 10,000-member Nation of Islam, has been the focal point of racial and political controversy for years and has been called a hatemonger by some for his public criticism of Jews, whites and some black leaders. Recently, he has characterized statements attributed to him as distortions and has said he is trying to mend fences.

Stallings, a Roman Catholic priest for 15 years, broke from the Washington archdiocese a year ago, calling it hopelessly racist. Former associates have said the conflict was fueled by allegations that he used church money to furnish his home, had sexual relations with altar boys and put a friend on the church payroll. Stallings, bishop of his own African-American Catholic Congregation, has declined to comment on these allegations.

The controversy over their exclusion began Thursday when Farrakhan attempted to attend the trial but was turned away by federal marshals, on Jackson's instructions.

When Barry's chief defense lawyer, R. Kenneth Mundy, inquired about the action in open court, Jackson said that Farrakhan's "presence would be potentially disruptive, very likely intimidating," and he would be barred from attending the trial. The discussion was held out of the jury's presence.

A similar scene was played out the next day when Stallings tried to attend. Stallings and Farrakhan had been given one of the four spectator passes allotted to the defense.

Jackson has declined to comment beyond his statements from the bench.

D.C. lawyer John D. Aldock, who was hired yesterday to represent Jackson, said, "Trial judges are entitled to considerable discretion in protecting the jury from distracting or disruptive influences, and we believe Judge Jackson properly exercised his discretion in this difficult case."

In 1987, Jackson excluded the public and press from the questioning of prospective jurors in the trial of former White House aide Michael K. Deaver. His order was challenged and overturned by the U.S. Court of Appeals.

Yesterday, Arthur B. Spitzer, of the ACLU's local chapter, argued that Jackson's decision in the Barry case violated the First Amendment rights of the men who were barred, as well as Barry's Sixth Amendment right to a fair and open trial.

But George Washington University law professor Mary Chey said Jackson may be within his authority because the trial remains public.

She added that a judge may take note of issues well-known in the community. Both men, she said, "are extremely controversial. Both espouse black separatist views and see the world largely in racial terms." Their presence, she said, could distract jurors, who must focus solely on the evidence.

Staff writer Sharon Epperson and researcher Matthew Lee contributed to this report.