A divided Colorado Supreme Court on Monday reversed a murder conviction for a woman who hit her boyfriend with a car, finding she must be deemed mentally competent before she can submit to mental health testing required for her defense. 

The state's high court voted 4-3 to order a new trial for Maria Laida Day, who was convicted of murder in a trial that hinged significantly on her mental state when she hit her boyfriend with the car. Day did not enter a plea of not guilty by reason of insanity, but wanted to put on evidence that she lacked the intent required for a charge of murder — including that she had failed to take prescribed antipsychotic medication in the days leading up to the killing.

State law required Day to undergo a mental health evaluation before she could present that mental-state evidence at her trial. Day was not competent to take the exam, but the trial court took the case to trial anyway, while preventing her from calling her psychiatric expert. This was a mistake, according to the state Supreme Court.

"The prosecution relied heavily on Day's post-event demeanor to prove her culpable mental state, and the trial court's ruling denied Day the opportunity to rebut that evidence," Justice William W. Hood III said in the opinion. "Therefore, we affirm the division's reversal of Day's conviction as to each count for which her culpability was at issue, and we remand the case for a new trial consistent with this opinion."

Day's case traces back to July 2015 when she hit and killed her boyfriend with her car as she drove away after dropping him off in front of a business. Day turned herself in to law enforcement, with police noting that she seemed calm, and possibly under the influence of drugs, the opinion said.

Prosecutors charged Day with second-degree murder, vehicular homicide and leaving the scene of an accident, and sought sentence enhancers. Day refused to plead not guilty by reason of insanity, but still sought to introduce expert testimony about her previous mental health diagnoses, the opinion said.

Colorado law requires that a defendant who wishes to introduce evidence about their mental state first submit to a mental condition exam conducted by state health officials. 

Day's expert witness conducted a sanity evaluation and found that Day was exhibiting "overt psychotic symptoms," while in jail awaiting trial. The expert also noted that Day had failed to take prescribed antipsychotic drugs in the days leading up to the incident, the opinion said.

Day sought to introduce the expert's report in her trial, and in February 2016 a trial judge required that Day sit for an independent evaluation from state health officials. The evaluation process would extend several years before a determination about Day's competency would finally be reached.

Mental health officials in Colorado initially asked for multiple extensions of a court-imposed deadline before Day was finally admitted for an interview. Officials then claimed that Day refused to complete the exam because of confusion about whether the exam was to be used as part of an insanity defense plea. 

Day would finally be administered a competency exam, which is different from the court-ordered mental-condition exam, in June 2018. It found her incompetent to proceed. Mental health officials diagnosed Day with "a form of schizophrenia" that had worsened while she was incarcerated, the opinion said.

Prosecutors sought to exclude Day's expert witness, claiming that Day refused to participate with the mental-condition exam. The trial court sided with the government, finding that because of the procedural issues with the exam, the expert witness could not testify.

A jury convicted Day on all charges and sentenced her to 35 years in prison. An appeals court reversed the conviction, finding that Day shouldn't be faulted for her nonparticipation in the exam process and allowed to bring her expert witness, the opinion said.

The government appealed to the state's high court and the majority ruled that while the appeals court was correct to reverse, it did so for the wrong reason. The high court's majority said the incompetency finding by health officials meant that the prosecution of Day should stop until her sanity is restored, the opinion said.

The three-justice dissent agreed Day should not be faulted for not participating, but found the trial court had a requirement under state law to not allow Day's witness to move forward without the required exam.

"Because Day had never undergone the requisite examination, the trial court was required by statute to exclude her proffered mental-condition evidence," Justice Monica Márquez said in the opinion. "The majority avoids this outcome by inexplicably shifting the burden of ensuring that the examination takes place from the proponent of the evidence, the defense, to the trial court."

A spokesperson for the Colorado Attorney General's Office declined to comment.

An attorney representing Day did not respond to a request for comment.

The government is represented by Philip J. Weiser and Frank R. Lawson of the Colorado Attorney General's Office.

Day is represented by Megan A. Ring and Andrew C. Heher of the Colorado State Public Defender's Office.

The case is People of the State of Colorado v. Maria Laida Day, case number 24SC16, in the Colorado Supreme Court.

--Editing by Linda Voorhis.