The trial had been scheduled to begin in February with jury selection. The judge postponed the trial indefinitely so attorneys can further argue whether Holmes should undergo further psychiatric evaluation.
Arapahoe County District Judge Carlos A. Samour Jr. ordered both sides to submit written arguments on further psychiatric evaluation and tentatively scheduled hearings for Dec. 17 and 18.
Holmes, 25, pleaded not guilty by reason of insanity to charges of killing 12 people and injuring of 70 during a packed midnight showing of Batman film "The Dark Knight Rises" in Aurora, a Denver suburb, in July 2012.
Prosecutors are seeking the death penalty.
Holmes underwent a mandatory sanity evaluation at the state hospital last summer. The results haven't been made public.
Colorado law defines insanity as the inability to tell right from wrong, so a defendant could have a mental illness but still be legally sane.
Defense lawyers said in March that they might have their own doctors evaluate Holmes, but they haven't confirmed whether they did so. The attorneys have acknowledged he was the shooter but said he was "in the throes of a psychotic episode."
If jurors were to find that Holmes was insane, he would be committed indefinitely to the state hospital. If doctors there ever concluded Holmes' sanity had been restored, he could one day be released, but that is considered unlikely.
Law enforcement officers have testified that Holmes planned the attack for months, stockpiling guns and ammunition. They also say he elaborately booby-trapped his apartment with bombs designed to explode and divert police and fire crews from the theater.
Prosecutors want to use that evidence to undermine the insanity claim by showing the attack was meticulously planned and that he knew it was wrong.
The Associated Press contributed to this report.