Nearly three years after James Holmes opened fire in an Aurora, Colo., movie theater during a midnight screening of "The Dark Knight Rises" – killing 12 people and injuring another 70 – the trial to determine his guilt began Monday.
Mr. Holmes has admitted to being the shooter, but is arguing that he is not guilty by reason of insanity. The trial, which is expected to last for several months, will determine whether that insanity defense is successful. If jurors agree he was insane at the time of the shooting, he will be committed to a state psychiatric hospital. If not, they will have to determine his sentence: life without possibility of parole or the death penalty.
It may be the first time a Colorado jury has ever had to weigh the insanity defense in a death penalty case, say legal experts.
"I don’t know that Colorado has ever had a death penalty case involving the insanity plea," says Karen Steinhauser, a former prosecutor and Colorado defense attorney.
The state is also ambivalent in its attitude toward capital punishment, and some see the Holmes case as a referendum on the death penalty. Since 1976, when capital punishment was reinstated in the US, Colorado has executed just one prisoner. It currently has three prisoners on death row.
But mounting a successful insanity defense in such a serious, high-profile case is extraordinarily difficult, say legal experts.
"As a general matter, it's very hard to win an insanity plea in a serious case like this, because the jury pretty much figures if you do the crime, you have to do the time," says Christopher Slobogin, a law and psychiatry professor at Vanderbilt University.
To be successful, defendants need to demonstrate a long history of psychiatric evaluations and evidence and bizarre behavior and thinking at the time of the offense, says Professor Slobogin – and even then, they almost never win in homicide cases, much less a horrific, multiple-homicide case like the Aurora shooting. "Just looking at it in the abstract, this is going to be a very tough case to win at trial," says Slobogin.
The Holmes trial took years to begin, as Holmes underwent psychiatric evaluations and both sides filed motions about the death penalty and the insanity plea. And there has been a great deal of anticipation, both due to the high-profile nature of the shooting and the fact that not much is known about much of the evidence that will be presented at trial.
"The opening statements will be the first time jurors and the public really know what his mental health history has been," says Ms. Steinhauser.
On Monday afternoon in his opening statement, District Attorney George Brauchler emphasized Holmes's "superior intellect," his premeditation, and his seemingly rational thinking on the night of the shootings – where he had seemed to make plans for a getaway, but changed those plans when he realized police were there and he was unlikely to be successful. Mr. Brauchler also cited two independent psychiatric evaluations done at the direction of the court, about a year apart. "Both of them said the same thing – that that guy was sane when he tried to murder all those people in that theater back in 2012," said Brauchler.
Throughout the trial, prosecutors are likely to emphasize Holmes's intent, and the premeditated nature of the shooting, for which he bought weapons and ammunition in advance.
Neither premeditation nor intent is actually at odds with insanity (a legal term rather than a mental-health term, and which is more about the reasons someone commits an offense rather than their intent to do harm), says Slobogin. But, he adds, it is very difficult to convince juries of that.
Holmes's attorneys, on the other hand, have said he was "in the throes of a psychotic episode," and will point to evidence of increasing psychiatric issues even before the shooting.
The defense will be "putting on the case with their experts that it doesn’t matter how much planning went into something, if someone doesn’t understand right from wrong … then planning is part of that disease, and it doesn’t necessarily mean the person was sane," says Steinhauser.
The defense also hopes that, even if they're unsuccessful in convincing the jury of Holmes's insanity, their evidence may influence the jury somewhat when it comes to sentencing – increasing the likelihood of a life sentence rather than the death penalty.
Nineteen women and five men were chosen for the jury, chosen from a pool of about 9,000. During selection, "both sides did a good job of really talking to jurors about their perceptions, and trying to pick those people to sit on jury who, while they may have experience dealing with mental illness, will keep an open mind," says Steinhauser.
Prosecutors, she notes, hope that having some experience with mental-health issues means jurors will understand there are varying degrees of mental illness and that "not everyone who has a mental-health issue is insane." Defense attorneys, meanwhile, hope that experience may help jurors understand the ways in which mental illness can affect someone's thought process and decision making.
There is little history for someone winning with an insanity defense for such a serious offense – though there are also few mass shooters who make it to trial, given that many are killed by police or kill themselves.
Earlier this year, a Texas jury rejected the insanity defense in the case of Eddie Ray Routh, who was convicted of killing "American Sniper" author Chris Kyle and his fellow Marine Chad Littlefield. In that case, prosecutors had not sought the death penalty, and Mr. Routh was sentenced to life without parole.
Colorado is in the minority of states in that it puts the burden of proof for an insanity plea on the prosecution rather than the defense: It's up to prosecutors to prove beyond a reasonable doubt that Holmes was sane at the time of the shooting.
But it's not clear, says Slobogin, that it will make a difference. "Research suggests that burden of proof don’t have a huge impact on juries’ ultimate conclusion," he says.
Slobogin cites two modern examples of high-profile cases in which an insanity plea was successful: Andrea Yates, who drowned her five children in a bathtub, and was found not guilty by reason of insanity in a retrial; and John Hinckley, who attempted to assassinate President Ronald Reagan in 1981. In both cases, he says, the defendants' bizarre behavior at the time of their offense helped convince juries.