A CASUAL EXCHANGE between U.S. Spreme Court Justice Potter Stewart and William Brennan as reported on Page 324 of the book "The Brethren" ought to send a chill through the lawyers and judges who work in the District of Columbia criminal courts.

The exchange reportedly occurred five years ago when someone mentioned the trial of former White House domestic affairs chief John Ehrlichman, who had just been convicted in federal court here of conspiracy and perjury.

"Stewart said that, as a white man, he would not want to be tried in the District of Columbia, where the juries were predominantly black," the book says. Brennan reportedly replied in agreement, "You bet your a--."

The authors, Bob Woodward and Scott Armstong, said yesterday they wrote those lines very carfully and drew no conclusion from, what was said by the justices. But the simple fact that the issure of black or white was even mentioned disturbed some people.

H. Carl Moultrie I, the chief judge of the D.C. Superior Court, cringed when these lines were brought to his attention. Moultrie, who is black stood at the desk in his chambers, a fresh copy of the book in his hands. He refused to believe that such things were ever said. t

"We would be really guilty of violating everything we've fought for if we start equating justice with color," Moultrie said as he ran his fingers throught the leaves of the book.

"I can't believe, frankly, that they (the justices) said it. I have too much respect for their. . . belief in this system of justice to believe they said it," Moultrie said.

He shook his head and stared out a window into the early afternoon sun. Not Brennan, he said first, and not Stewart.

"No intelligent person would make that stupid statement," Moultrie said.

For Moultrie, who has presided over some of the most serious criminal trials in the District of Columbia involving both black and white defendants, it is painful for anyone to imply that fairness is compromised in his courthouse.

If concerns are raised about the racial composition of a jury -- and those concerns do come up quietly on both the prosecution and defense side -- its's usually when the jury's members are selected. A potential juror's age, employment, home address and sex often are the critical factors in this very unscientific selection process. When lawyers playing with intuition.

"When you pick a jury you are looking to their prejudices," said defense lawyer Phillip J. Hirschkop. "You appeal to prejudices" and remove the jurors who don't seem to be on your side. Every lawyers does that. Everyone has prejudices.

"I don't see anything wrong with two Supreme Court justices recognizing [jury prejudice] as a fact of life," Hirschkop said.

Defense lawyer Plato Cacheris said that juries in Washington are tough on white-collar criminals "regardless of the color of the defendant.

"A white defendant, assuming he's got a good defense, will get as fair a shake as any other defendant," Cacheris said.

U.S. District Court Judge George L. Hart Jr. emphatically agrees. However, Hart, like Moultrie and others, simply does not believe that Justices Stewart or Brennan ever made the statements reported in "The Brethren."

A spokesman for the Supreme Court said yesterday that there would be no comment on the book. Author Armstrong said "we had several sources on that conversaion and they agreed.

"We wrote that very carefully because we didn't want to draw any conclusions from it," Armstong said.

Judge Hart, continuining his line of thought cited the trial here of former Texas Governor and Treasury Secretary John B. Connally, which he presided over in 1975. ". . . The outcome of [that] case showed beyond a doubt that he could and did get a fair trial," said Hart, who is white.

In April 1975, Connally, the former governor of Texas, was acquitted by a federal jury in Washington of charges that he accepted an illegal gratuity of $10,000 from dairy producers in 1971 while Connally was then-President Nixon's Treasury Secretary. The jury in that case was predominantly black, Hart said in an interview. Connally's lawyer, Edward Bennett Williams, had argued that his client could not get a fair trial in Washington, although he did not say precisely why, Hart recalled.

The Watergate trials provoked supporters of the Nixon White House to charge that white American defendants couldn't get a fair trial in a town where jurors are primarily black Democrats. It was at the time of these discussion that the justices reportedly made the comments cited in "The Brethren."

In 1974, after the perjury trial of former White House appointments secretary Dwight L. Chaplin, defense attorneys presented an affidavit from a black psychiatrist who testified it would be reasonable to expect black jurors in Washington to be tough on Nixon administration defendants. The psychiatrist cited the "constellation of historical and institutional forces" affecting blacks here that would account for a hostile attitude toward members of that administration.

Judge Gerhard A. Gesell, who presided at that trial, dismissed that argument, saying the jury of seven blacks and five whites acted on the evidence "free of bias." The jury foreman, a black Republican, was later quoted as saying "We bent over backwards to be fair."

At that time, a New York-based jury selection expert said he thought that middle-class blacks, especially those who live in Washington -- a government-oriented, middle-class city -- were extraordinarily conscientious about fair play."

The 1978 criminal trial of Rep. Charles C. Diggs Jr. (D-Mich.), the senior black member of Congress, is a telling example of how black jurors in Washington reacted in one instance when race became an underlying issue in the courtroom. Eleven of the 12 jurors in that trial were black.

Defense lawyers played heavily on Digg's civil rights background and his work toward achieving home in the District of Columbia. Four prominent civil rights leaders, including Coretta Scott King and then-United Nations Ambassador Andrew Young, testified to endorse Diggs' honesty and integrity.

The jury thought the character witnesses were "fine people," one juror said at the time. But what they said had nothing to do with the charges against Diggs Race never came up in the jury's deliberations, members said later. Diggs was found guilty of all 29 counts of mail fraud and illegal diversion of more $60,000 of his congressional employes' salaries to pay his own bills. The appellate court has affirmed Diggs' conviction.

At the time, jury foreman Leon C. Perry said it "bothered" him that both he and Diggs were black, but he nevertheless voted Diggs guilty.

"I would rather I didn't have to do it, but I had to do it because to me it [his guilt] was obvious," Perry said.

The D.C. Bar Board of Governors has put off final approval of a new Fee Arbitration Board until it makes a few changes in proposed bylaws and gets legal advice from bar counsel Wesley S. Williams Jr. Under the proposed new service, if a lawyer refused to accept arbitration of a legitimate fee dispute with a client, the Bar would provide a free lawyer to take the client's claim to court.

OBITER: David S. Tatel, former director of the Office of Civil Rights at the Department of Health Education and Welfare, has returned to Hogan & Hartson. . . After eight years at LeBoeuf, Lamb, Leiby & MacRae, Edward L. Cohen is now a partner at Tighe, Reukauf & Curhan. . . Robert L. McGeorge, formerly of Galland, Kharasch, Calkins & Short, has joined Webster, Johnston & McGeorge . . . Richard C. Johnson, James M. McHale and W. Bruce Shirk have been named partners at Seyfarth, Shaw, Fairweather & Geraldson. F. Keith Adkinson, Judith B. Ittig and Richard McKim Preston are now associates and William F. fox Jr. is counsel to the firm.