Lawyers for the Colorado cinema massacre suspect have said for the first time that they are considering entering a plea of not guilty by reason of insanity on behalf of their client.
But in court papers made public yesterday, they said they could not make their decision about their defence of James Holmes until the judge ruled on their motion challenging the constitutionality of the state's insanity defence law.
The lawyers say the law is unfair to defendants who invoke it because it requires the disclosure of potentially incriminating information, such as mental health records, while those who plainly plead not guilty are not required to turn over any evidence.
Holmes, 25, is accused of killing 12 people and wounding 70 during a midnight showing of the latest Batman film, The Dark Knight Rises, at the cinema in Aurora, outside Denver, last July.
He faces multiple charges of first-degree murder and attempted murder.
Prosecutors have not announced whether they will pursue the death penalty, but they have 60 days from when a defendant enters a plea to do so. Holmes' hearing is on March 12.
A legal expert said the manoeuvring may be part of a defence strategy to make sure prosecutors never get their hands on a notebook purportedly sent by Holmes to his psychiatrist and included descriptions of a possible attack.
The notebook was the subject of court hearings in the months after the shooting. Under state law, the notebook was protected because it was part of a doctor-patient relationship that Holmes had with the psychiatrist.
"That's why there's a big issue there, there's information that the prosecution may not be entitled to unless they plead not guilty by reason of insanity," said Karen Steinhauser, a Denver criminal defence lawyer and law professor, who was also a former prosecutor.
The judge has ordered lawyers not to speak publicly about the case.
Under state law, defendants who plead not guilty by reason of insanity must reveal to prosecutors mental health records as well as psychiatric evaluations that may include details of the crime for which they are accused.
While the law has not been challenged before in cases involving the death penalty, determining whether it violates a defendant's constitutional right against self-incrimination directly affects their decisions about Holmes' defence, his lawyers argue.
Ms Steinhauser said the defence had to file its motion challenging the insanity defence law before the plea was entered because they could not raise issues with the statute afterwards. They could however, raise other trial-related issues later.
Ms Steinhauser said the judge could rule on the matter, which will probably be appealed to higher courts and possibly delay Holmes' court appearance.
Holmes' lawyers have said their client is mentally ill and had sought the help of a psychiatrist at the University of Colorado, Denver, where he was a neuroscience graduate student.
In January he was ordered to stand trial following more than two days of evidence from police and government agents who provided excruciating details about the attack.
Holmes had been expected to enter a plea following that hearing, but the defence requested a delay, saying it would not be ready until March.
Legal experts say there may be few options for Holmes. If, as many anticipate, he enters the plea of not guilty by insanity, he would undergo lengthy tests at a state psychiatric hospital before trial.
If the case goes to trial and he is found not guilty by reason of insanity, Holmes could conceivably be released from a psychiatric facility some day if he is deemed to have recovered, but that is considered an unlikely possibility.
A guilty plea or conviction could mean life in prison or the death penalty.