KUSA - The man accused in the Aurora theater shooting is scheduled to be arraigned and enter a plea on March 12. New documents filed by James Holmes' defense gives insight into what that plea might be.

It will come as no surprise the defense is interested in pursuing an insanity plea, but such a plea comes with baggage. Holmes' lawyers want some of that baggage ruled unconstitutional before they commit to a plea.

9NEWS Legal Analyst Scott Robinson says the defense does make some good points.

If Holmes were to plead not guilty by reason of insanity right now, he would be waiving his 5th Amendment right - the right to remain silent and not to testify.

The defense would also have to turn over all communications between Holmes and people like his psychiatrist, which they do not want to do.

Finally, his lawyers want the judge to explain certain ramifications of an insanity plea. For example, if an insanity plea were entered, Holmes would have to undergo extensive mental evaluations. If Holmes were to not cooperate with doctors, would that be considered invoking the 5th Amendment, something he would have waived by pleading insane?

Robinson says the statutes the defense is challenging are relatively new, and haven't been challenged in this way before.

Robinson says no matter what the judge rules, it will create some sort of precedent.

"Defense lawyers are struggling with our 1999 insanity statute and the present day death penalty statute," Robinson said. "They don't like the way those two statutes interrelate. If Holmes enters a plea of 'not guilty by reason of insanity' and he chooses not to cooperate with the doctors, his lawyers may not be able to put on any evidence at all, even in the death penalty phase about a mental disease or condition."

An insanity defense would be an uphill battle against all the evidence the prosecution already has.

During the preliminary hearing in January, there were hundreds of pieces of evidence which appeared to show quite a bit of premeditation.

Signs of premeditation of any type is not good for an insanity defense.

It's unclear what kind of delay this statute challenge may have on the March 12 arraignment.

Attorneys also say not knowing whether prosecutors will seek the death penalty directly impacts what type of plea to enter at the March 12 arraignment or what type of defense to use.

Holmes is charged with multiple counts of first-degree murder and attempted murder in the July 20 Aurora theater shooting that killed 12 people and wounded 70.