A Pakistani Embassy chauffeur, charged with reckless driving in a January accident in which a pedestrian was killed in Arlington County, has been determined to be immune from prosecution.

Arlington General District Court Judge Francis E. Thomas dismissed the charge against chauffeur Ahmed N. Kalera, 31, in a hearing last week, ruling that Kalera is protected by a 1972 treaty guaranteeing embassy employes immunity from prosecution in connection with "acts performed in the course of their duties."

Kalera was driving on Arlington Boulevard (Rte. 50) at the intersection of North Park Drive when his car struck and killed Arthur B. Knight, 70, Jan. 23, according to court testimony. Police said Knight, who was living in an Arlington shelter for the homeless, was in the crosswalk when he was hit about 6:45 a.m.

Kalera's attorney, Morton Zuckerman, argued that the accident occurred while Kalera was traveling to pick up Capt. Mumtaz W. Khan, the embassy's naval attache, at his Vienna home. Assistant Commonwealth's Attorney Mark Exley said the case was the first he could recall in Arlington in which a question of diplomatic immunity reached the courts.

Typically, embassy officials will inform the court by letter or telephone that the person charged is immune from prosecution, and the matter is dropped, he said. "But we said they're going to have to come to court and prove immunity," Exley said.