The hearing for James Holmes begins at 11 a.m. ET.
A judge ruled Monday that Holmes must waive medical confidentiality and agree to be drugged for a psychiatric exam if he wants to claim that he is not guilty by reason of insanity. His lawyers had claimed that those provisions violated his constitutional rights.
The judge, William Sylvester of the 18th Circuit Court, also ruled that Holmes would have to turn over the names, addresses and medical reports of any doctor or psychologist who has treated him for a psychiatric condition.
The defense claimed in papers revealed last week that Holmes was hospitalized for several days last fall and required restraints.
Twelve people were killed and 70 injured in the July 20 shooting rampage at a midnight screening of the Batman movie "The Dark Knight Rises." Holmes surrendered to police within minutes of the attack.
At his first court appearances, Holmes had reddish-orange hair and a blank stare. At subsequent hearings, his hair has been more natural-looking and his demeanor more stable.
Colorado lawmakers on Monday advanced a package of legislation aimed at reducing gun violence in the state.
The Associated Press and Reuters contributed to this report.