Police say it couldn't happen in Maryland or the District. But in Virginia, if a policeman asks you for assistance and you refuse to help, you just might get arrested for it.

That's what happened to 40-year-old Fred Mason, owner of a trash service, early yesterday in Fairfax City.

A patrolman asked four bystanders to assist him in subduing a man who was subsequently charged with public drunkeness and breaking arrest, according to the officer and onlookers.

Mason, trucker Ron Day and two other men who said later they believed they were witnessing an act of police brutality when Officer Steve Haas asked for help, refused to get involved. Eight hours later, Mason was served with an arrest warrant for failing to help the officer. No one else was charged.

Officer Art Bennett, who served the warrant on Mason, said yesterday the statute is "damned rarely" invoked.

In the District of Columbia, police can deputize citizens, but citizens cannot be held accountable for refusing to help, according to department spokesmen.

High-ranking Montgomery County police officers said a similar statute once existed in Maryland, but has been eliminated.

In Virginia, under code section 18.2-436, arrests can be made if citizens willfully refuse to aid an officer in the execution of his duties.

"I'm very upset about it," Mason said. "There should be a way to counter-sue on this and I've been trying to get in touch with my lawyer all day."

Fairfax City Police Capt. Hazen L. Allen countered by saying, "If an officer is in an alligator den, there are some cases where asking for help is totally reasonable, asking anything you might expect a law-abiding citizen to do."

Most Northern Virginia police experts agreed that the statute is rarely invoked, mainly out of a desire to prevent harm from coming to innocent bystanders. But they spoke of situations where an officer in trouble might ask citizens to use a police radio to call for help, or simply to open a door so that an officer can leave with a suspect.

Allen said Haas was summoned to a Fairfax restaurant after the restaurant manager repeatedly demanded that 25-year-old Gary Hubert, a laborer-mechanic for Mason's Fairfax City trash business, leave the establishment. When Hubert refused, all sides agree, the manager called the police.

When the officer arrived, according to Allen, he asked Hubert to walk a straight line to prove he wasn't drunk.

When Haas told Hubert that he was under arrest for public drunkeness, Allen said, Hubert replied, "I'll kill you, you mother------," and tried to resist the arrest physically when Haas "got his attention with a flashlight."

Mason and Day claim that Haas struck Hubert repeatedly about the head with the flashlight. When Haas had subdued Hubert, Day said, Haas said "How about somebody helping me?"

Day said yesterday he was "not going over there where he could whip me with that flashlight, too."

There was no immediate explanation why Mason, rather than the other bystanders, was charged with refusing to assist Haas. Allen said that "maybe Mason was the only guy he could identify."

Both Mason and Hubert are scheduled to appear in Fairfax City's General District Court on Oct. 21.

If convicted of refusing to aid an officer, Mason could be sentenced to up to six months in jail and/or a $500 fine.