IT IS ONE of those silences peculiar to the courtroom, when no one moves, and the only sound is the breathy hum of the ventilator. Judge Barrington D. Parker is looking up something in a law book. Everyone is frozen, a tableau, a still from a movie.

Then he says, bemused, "Apparently not." And at those cryptic words the room comes to life again.

It is a bitter little case. A government office supervisor is fighting for her job, and she is on the stand explaining the stack of memos she has written criticizing her staff.

The judge keeps asking her if she really meant this phrase or that. Soon a full-scale interrogation develops, while the lawyer who had been asking the questions stands by, drumming his fingers on the lectern.

They say sometimes that Judge Parker gets too involved in his cases at D.C. District Court. They say he repeats questions, draws out witnesses, hassles the lawyers.

Certainly he calls attorneys to the bench often enough. But what he is doing then is trying to cut through their legal obfuscation, break up their word games and get the trial moving again. And when he quizzes witnesses he is trying to collect as much information as he possibly can, since in the end he will be the one making the decision.

And when he asks a defendant, in rapid succession, where he lives, with whom he lives, how long he's been here, where his parents are, what kind of job he has, it is apparent that the judge is bringing this person into living focus, making him actual and palpable and not simply a name on a probation report.

Once, at the end of a long day, a prisoner was brought before him for arraignment. The first thing Parker asked the man was: "Did you get any lunch? Will you be in time to get supper when you go back to the cell?"

Then he apologized to the man for making him wait all day.

"I don't mind confessing that I inject myself into cases too much at times," the judge told a visitor later. "I'm considerably more restrained in jury cases, of course. You have to allow the lawyers to try the cases, even if they're not very good. But when they take up too much time . . . ."

When they take up too much time, Judge Parker doesn't hesitate to catechize them on a fine point, or go to the law books himself, or remind them once again that "so much can be accomplished, gentlemen, by just calling someone on the phone and discussing it."

The courtroom is his element, and woe betide the attorney who thinks that because he is leaning back in his chair, eyes closed, he is napping. For suddenly he will lunge forward, startling the witness into silence as he queries some bit of testimony.

"A judge has a responsibility, as I see it, to see that justice is done and each litigant given his day in court."

Parker pauses to consider these words. Maybe he feels they sound a bit too grand, for he adds, "I've got my fair share of reversals." He chuckles.

In June he shot down Jimmy Carter's whole wage-price guidelines program because he felt the president had exceeded his constitutional authority by threatening violators with denial of federal contracts.

Barrington Parker was also the judge who berated Richard Helms, the ex-CIA director, for considering himself above the law. "You now stand before this court in disgrace and shame," Parker thundered. He fined Helms $2,000 for failing to tell the Senate about CIA adventures in Chile.

And there was the Westinghouse case, when that industrial giant tried to settle a foreign bribery case without identifying the official involved -- or even naming the country.

"It was just a couple of lawyers who came in one moring and asked me to sign the plea. They had a document almost two inches thick, and I said, well, of course, I'd have to read it first. They seemed somewhat surprised. I said to come back that afternoon."

It turned out that Westinghouse was agreeing to pay $300,000 in fines and plead guilty to making false statements to U.S. agencies which had financed construction projects in the unnamed country. The fine wasn't even as much as the $322,000 supposed to have been paid by Westinghouse to get the contracts.

"That afternoon, they came back with a retinue of spear carriers. A whole gang of 'em. I said. 'Who are you?,' and they looked around as if they'd never seen all these people before."

He still hadn't read the paper. He took it home, and that night heard over the radio that "Judge Parker has accepted the plea and levied the fine." The announcement was based on a Westinghouse press release.

Never a great fan of plea bargaining anyway, the judge went through the roof, refused to "rubber-stamp everything you hand the court" and caused the names to be named. The country was Egypt, and the official was Ahmed Sultan Ismail, a deputy prime minister.

Ever since he came to the federal court in 1969 as a Nixon appointee, in fact, Parker has been noted for his independence of mind. In '73 he forbade the Nixon administration to set up price controls. He took on the National Guard when it tried to prevent longhaired soldiers from wearing short-haired wigs on duty. He pioneered the use of lie detectors as evidence here.

The judge, who will be 64 this month, insists he's not special at all, that "we've got a good group of judges here, that anyone else would do the same. He doesn't go in for what he calls grandstanding and notes that "those who live by the press die by the press."

Parker has been called "crusty, strict," and "hell on defense attorneys," and also "sensitive and loving" (by Marjorie, his wife of 40 years), but he is first and last a modest man.

It was easier for him to talk about his father and his two sons than about himself. His father, Barrington Sr., came up the hard way, from mailman to lawyer, helped found the Robert H. Terrell law school at 13th and U streets ("the town was completely segregated then, and Howard was the only black law school, but it was a day school, and this was a night school") and taught there six hours a week for token pay. He was also a part-time minister for 53 years.

As for the sons, Barrington Jr. is a Park Avenue lawyer in New York, with Parker, Auspitz, Niesemann and Delehanty ("quite a ticket," the judge smiles), and Jason is a Chinese scholar with an advanced degree from Princeton. There is one granddaughter.

Parker's own education, after Stevens and Dunbar, took him to Lincoln University, the alma mater of four black federal judges including Thurgood Marshall, and later to the universities of Pennsylvania and Chicago.

"I was a late bloomer," he says. "I was admitted to the bar here in '47. I started in economics, but I knew it would break my father's heart if I didn't go to law school."

When the judgeship came around, Parker was naturally a candidate, being an active Republican. On the other hand, with his usual independence, he had disavowed Goldwater in 1964, so his appointment was debated for months.

In 1975, the judge was hit by a car as he walked across Connecticut Avenue to buy some cigarettes.

"I was on my way to teach at American University, and I didn't want to be bumming cigarettes from the students," he remarks. Partly paralyzed for a while, he eventually lost his left leg. Today he walks on metal crutches.

He hasn't smoked since that night.

It bothers him that he can't get around as fast as he might. Just before the trial of three Cuban exiles charged with the Letelier car-bombing murder, he got several threats, one of them a pointed reminder of his condition plus a description of his car.

"I was transfixed," he says. "I got rather excited about it before the trial, but you know, after a while the whole question of security becomes a bore."

He has trouble sleeping, so he reads a lot, mostly historical fiction. His wife, who is a former D.C. city council member, keeps him in books.

"She was my high school sweetheart at Dunbar. She's on the University of D.C. board now. We've both taught there."

He also taught at Terrell, when his father was dean. His mother was a teacher, too.

Somehow, whatever we talk about, we find ourselves back with the law before long. He is bothered by wide latitude that prosecutorial discretion gives to government lawyers. He worries about white collar crime, of which he sees a great deal, but thinks the public is taking more interest in it. He hopes "to be spared the accusation of being partial to any defendant."

"To be candid," he adds, "I don't know all the answers. I don't read the Bible very often, but there is a line in Micah 6 that means a lot to me. I can't quote it exactly."

But he does. It goes: "And what doth the Lord require of thee but to do justly and to love mercy and to walk humbly with thy God?"