James Holmes' attorneys have filed six new constitutional challenges against the death penalty, saying execution is cruel and unusual punishment.
The challenges also say executions in Colorado are arbitrary.
Holmes pleaded not guilty by reason of insanity to killing 12 people and injuring 70 others when he opened fire in an Aurora theater on July 20, 2012. He is scheduled to go on trial for 166 counts in February and prosecutors are seeking the death penalty.
The motions were among 25 made public Tuesday. They were filed last week.
The defense filed two other challenges to Colorado death penalty laws in August, saying they don't set clear standards and make it too hard for jurors to weigh mitigating factors.