Preliminary hearings on the Aurora movie theater massacre began today, and many expect accused shooter James Holmes to pursue an insanity defense. Considering Colorado's unusual laws, he could have a strong case.

Reporters, victims' family members, and others closely watching the fallout from last July's grisly mass shooting are flooding the Arapahoe County District Court today as evidentiary hearings finally begin in the case. At the end of this closely watched "mini-trial," expected to last throughout the week, Judge William Sylvester will have to determine whether or not there's enough evidence to bring Holmes to trial. Legal experts already see plenty of reason to justify charging Holmes with more than 160 counts of first-degree and attempted murder. But there's still a good chance this could be the case's endgame, if Holmes takes a plea bargain. Holmes's attorneys say their client suffers from a mental illness, and NBC News reports that they've subpoenaed two witnesses to speak on Holmes's sanity. Chances look strong that they'll mount an insanity defense.  

And if they do, they may be able to stave off the death penalty more easily thanks to Colorado law. When it comes to pleading insanity, the burden of proof falls on the defense in the vast majority of states. Basically, if defense lawyers say their client is insane, they have to prove it themselves. It's just the opposite in Colorado, one of the few states that requires the prosecution to establish the defendants' sanity in order to dismantle an insanity defense. "The law is this in Colorado," criminal defense attorney Anne Bremner explained this morning on CNN. "The state has the burden of proving beyond a reasonable doubt that James Holmes is sane ... How do they prove that? That's tough."

Imagine being the prosecutor tasked with disproving—beyond any reasonable doubt—the insanity of someone like James Holmes. How would you explain Holmes reportedly telling police he was the Joker? Or why he showed up to court with dyed orange hair and behaved so strangely? Notebooks full of violent plots, bottles of prescription medication retrieved from his apartment, and an attempt to call his psychiatrist just minutes before the shooting ... you'd have your work cut out for you trying to convince jurors that the defendant was perfectly sane when he entered the Century 16 movie theater.

It would be especially hard to demonstrate Holmes's sanity because Colorado has a hybrid way of establishing legal insanity. Colorado, like many states, follows the M'Naghten rule. This test basically determines whether or not the defendant knew what they were doing was wrong at the time of the crime. This means that if the defense can establish Holmes was unaware of the fact that his actions were wrong, he could enter an insanity plea. But even if he fully knew what he was doing was wrong, he could still claim insanity under Colorado's other criteria—the irresistible impulse. This holds that even if Holmes knew his actions were wrong, he could still be considered insane if he was unable to stop himself from carrying them out. 

However, Holmes's team does not have a slam-dunk insanity case—not by any means. Former president of the National Association of Criminal Defense Lawyers Lisa Wayne tells Voice of America that while defense attorneys in Colorado don't have to shoulder the burden of proof in an insanity case, they do have an uphill climb in presenting credible evidence for entering an insanity plea in the first place:

Can we show that, in fact, this is someone who really was planning and there was premeditation and those kind[s] of things? Or is there really a likelihood that this person has a mental disease or defect? ... The mental health part of it is very important in terms of lining up credible psychiatrists, doctors who can really, in a credible fashion, say this defendant is just suffering from an extreme mental illness.

On top of that, the University of Colorado, Denver psychiatrist Holmes met with—and who reported concerns to campus police—may not be able to testify due to the doctor-patient privilege. Even with the loss of that witness, the defense's case if they choose to pursue an insanity defense seems strong under Colorado law.