Lawyers will make their closing arguments this morning in the sixth day of the trial of a D.C. police officer accused of punching two people he arrested.

The officer, John Hilderbrand, is charged in D.C. Superior Court with simple assault in connection with two incidents in 1988. If convicted of the two misdemeanors, Hilderbrand could face up to two years in prison.

The prosecution alleges that in June 1988, Hilderbrand struck Royette Smith in the face several times after their cars nearly collided.

At the time, Hilderbrand was off duty and wearing civilian clothes.

Three months later, according to the charges, Hilderbrand struck Everett Richardson four or five times after he had arrested Richardson and placed him in the back of a police car.

Hilderbrand, who testified yesterday, disputed both accounts.

While admitting that he struck Smith and Richardson, he said he was using only the minimum force necessary to make an arrest and was acting in self-defense.

In her testimony, Smith said that after the near-collision, Hilderbrand left his car and asked Smith, now 25, for her driver's license and registration. When she reached for her purse, Smith said, Hilderbrand reached into her car and tried to remove the keys from the ignition.

When she placed her hands on the keys, Smith testified, Hilderbrand began hitting her on the side of the face. To protect herself, Smith said, she rolled up her window on Hilderbrand's arm.

Hilderbrand, who has been on the force for eight years, testified that when he reached into the car, Smith began clawing him with her nails and then rolled the window up on his arm.

He said that she then put the car into gear, and when it began to roll backward, he struck at Smith to try to make her stop.

When other officers arrived, Smith was arrested. The charges were soon dropped.

Smith also filed a complaint against Hilderbrand before the Police Civilian Complaint Review Board, which found in her favor. Hilderbrand was placed on special duty, which involves no personal contact with civilians.

Prosecution witnesses, who included two police officers, testified in connection with the September 1988 incident that Hilderbrand punched Richardson after arresting him and putting him into a police car.

Richardson said he accidentally kicked Hilderbrand while trying to sit upright.

Hilderbrand testified that he believed Richardson was trying to escape and was kicking at him intentionally. He said that punching the suspect in the collarbone was the safest way to subdue him.