Judge Debra Nelson on Monday denied a prosecution request to keep out parts of a toxicology report that shows Martin had small amounts of marijuana in his system.
Prosecutors argued the information would be prejudicial.
But defense attorneys said it was relevant since Zimmerman believed Martin was under the influence at the time he spotted him in his neighborhood.
Zimmerman is pleading not guilty to second-degree murder. He is claiming he fatally shot Martin in self-defense.