In a court motion made public on Wednesday, attorneys for James Holmes acknowledged that he murdered 12 people and injured dozens more.
However, his attorneys say Holmes was "in the throes of a psychotic episode" at the time.
"Holmes suffers from a severe mental illness and was in the throes of a psychotic episode when he committed the acts that resulted in the tragic loss of life and injuries," Holmes' lawyers wrote.
The motion asked that Holmes be unrestrained at his upcoming trial., saying it was "not appropriate." The judge denied the request, and Holmes will be tethered to the floor.
"The Court chose the least restrictive form of restraint available and the one that could be hidden from the jury's view," wrote Judge Carlos Samour.
Holmes has pleaded not guilty by reason of insanity to 166 counts of murder, attempted murder and other offenses - a plea that stops just short of a confession.
Prosecutors are seeking the death penalty.
The Associated Press contributed to this report.