The white Chicago police officer was charged with first-degree murder in the black 17-year-old's October 2014 shooting death.
Police dashcam video shows Van Dyke shooting McDonald 16 times. Van Dyke was charged in November 2015, shortly before the video was released to the public.
Van Dyke's attorneys said McDonald's juvenile records, from his time as a state ward, are necessary to prepare their client's defense. Van Dyke claims he shot McDonald in self-defense.