The trial of Kevin Cooper, charged with the highway deaths of five members of a Montgomery County family last Christmas Eve, opened here today, having been moved 135 miles to the Eastern Shore from Carroll County after a judge in Westminster tried unsuccessfully for three days to pick an impartial jury there.

Carroll County Circuit Court Judge Donald J. Gilmore had denied an earlier motion by Cooper's attorneys to move the trial because of extensive publicity surrounding the case but in an order made public today, the judge said he now agrees that an impartial jury could not be found in Carroll County, scene of the accident last Christmas Eve.

This afternoon a jury had been selected here at the Talbot County courthouse, and the judge said testimony would begin Friday. The trial is expected to last a week.

Cooper, a 26-year-old carpenter, faces a variety of charges including drunk driving and automobile manslaughter as the result of the accident last Dec. 24.

Police said Cooper was on his way home to Glen Burnie from a Christmas party when his car collided head-on with an automobile driven by Martha Proctor of Clarksburg.

Proctor, the wife of Col. Richard O. Proctor, commandant of students at the Uniformed Services University of the Health Sciences in Bethesda, was on her way to a Christmas Eve church service with her family.

Killed in the crash, which occurred on Rte. 27 near Mt. Airy, were three of the Proctors' grandchildren, ages 1 month, 18 months and 3 years, and two sons, ages 14 and 23.

Martha Proctor and two daughters were injured in the accident. Cooper, who also was injured, has been free without bond since his release from the hospital.