A law school graduate who testified that he was beaten by District police officers after they arrested him on a drunk-driving charge has been awarded $950,000 in damages by a federal court jury.

Arthur David Leach, 34, who now lives in Palm Springs, Calif., testified in U.S. District Court here that he was so badly traumatized by the officers' rough treatment that he has been unable to work regularly for two years, even though he had no fractures or other injuries that required hospitalization.

The verdict, presented late Monday, marks the third time in six months that a jury here has found against District police officers in a case involving allegations of police brutality. The judgments in the other two cases, both now on appeal, total $732,500.

"I think the jury reflects the attitude of the people of this city," said Leach's attorney, Robert N. Lewis, "that they will not let the police get away with this kind of conduct."

Assistant D.C. Corporation Counsel Cary D. Pollak said the District probably will ask Judge June L. Green to set aside the verdict against Officers Thomas J. Ross and John Schmitt, who strongly denied the allegations in court testimony. But Pollak said the city government would have no other comment on the jury's decision.

However, Gary Hankins, chairman of the Fraternal Order of Police, the union that represents the District's 3,400 police officers, said the string of jury verdicts against D.C. police was "a bum rap." He said the verdicts had hampered law enforcement by making policemen "less aggressive than we otherwise might be."

"We don't want a police force that hassles the community or harms innocent citizens," Hankins said. "But I think D.C. has gone so far the other way that if there's a tough one to call, officers think 'I'm not going to get involved' and they avoid tough confrontations."

Hankins said he thought the large verdicts reflected the jurors' sympathy for the underdog and a belief "in a city where billions of dollars are thrown around every day, that the government has deep pockets to pay a few hundred thousand dollars here and there."

In late April a federal court jury awarded $207,500 to Stanley Wiggins, 28, an unemployed veteran, who said he was knocked unconscious and lost four teeth when he was hit with a billy club by two D.C. police officers.

In October a jury awarded $425,000 to Don R. Parker, 37, a suspect in a robbery case, who was shot and wounded by D.C. police who had gone to his home in Prince George's County to ask his wife about his whereabouts.

Police said they used the billy club because Wiggins was unruly. They said Parker was shot after he tried to elude capture and one officer thought he was reaching toward his belt for a gun, although later no weapon was found.

In Leach's case, the jury of five women and one man deliberated for one hour before reaching their verdict after a five-day trial.

Leach, who formerly lived in Silver Spring, said he was driving to a girlfriend's house after repairing his car when he was arrested by police at 13th and O streets NW shortly before 4 a.m. on Sunday, Sept. 30, 1983. He said he had graduated from American University Law School in May 1982 but had not yet taken his bar exam and was working as a practical nurse.

Ross, 35, who has served on the D.C. police force for 15 years, testified that he stopped Leach's car because it was weaving down 13th Street. After the car had stopped, Ross said, he smelled alcohol on Leach's breath. He said Leach tried to walk away from him and refused to take a breath test.

Leach testified that he had not been drinking and that the officer slammed him against the side of a car and taunted him when he found out he was a lawyer. He said that when police brought him to D.C. General Hospital, Schmitt put a pistol to his forehead and pulled the trigger.

Schmitt testified that he never pulled a gun on Leach and said the plaintiff was loud, boisterous and uncooperative.

The drunk-driving charge against Leach was dropped after his license was suspended because he did not take the breath test.

A key witness for Leach was Dr. Stephen Sonnenberg, a psychiatrist, who said Leach was suffering from "post-traumatic stress disorder" that severely impaired his ability to function normally. He said Leach still requires extensive medical treatment.

Leach said he took the California bar exam last summer and is still awaiting the results. He said he has been working part time recently as a clerk at a law firm in Palm Springs, and hopes to be hired there as a lawyer if he passes the bar.

The jury awarded Leach $500,000 in compensatory damages and $450,000 in punitive damages.