The Colorado Supreme Court on Monday ruled that criminal defendants must have a "compelling and legitimate need" for forcing their prosecutor to testify, concluding that a trial court judge in Boulder County was wrong to force such testimony in an assault case.

The opinion came in the case of Harold Lloyd Honstein, accused of assaulting his roommate. The roommate initially told police that Honstein had punched her and threw a full soda can at the back of her head, according to the opinion. The prosecutor heard the roommate partially recant ten months later, stating that she hadn't actually been punched, the opinion said, and she repeated that assertion to an investigator three days later.

The roommate explained to the investigator that she had mistaken the soda can being thrown at her for being punched, the opinion stated. Though the prosecution offered to stipulate to the partial recantation, Boulder County Judge Elizabeth Brodsky ruled that the prosecutor who heard the roommate recant must testify in the case.

That was a mistake, the Colorado Supreme Court ruled, with Chief Justice Brian D. Boatright writing that the novel legal question was one "of significant public importance," as the high court had "yet to determine what standard applies when a defendant subpoenas a participating prosecutor to testify at trial."

The strict distinction between advocate and witness is fundamental to the justice system, Justice Boatright noted.

"As a fundamental proposition, we ask juries to base their decisions on the facts before them, not the credibility or reliability of the advocates," Justice Boatright wrote. "Consequently, a participating prosecutor's testimony, although rare, can compromise the integrity of the adversarial process."

The court agreed with prosecutors that it had to step in now, rather than after a trial, because the government would have no recourse if Honstein were to be acquitted.

Justices noted that they were adopting "the federal approach" to the situation, holding that a defendant seeking to put a prosecutor on the witness stand has to show "a compelling and legitimate reason to do so," citing a 1997 decision by the U.S. Court of Appeals for the Second Circuit.

And to be compelling, the testimony has to be essential to the case and unable to be sourced somewhere else.

Boulder prosecutors contended that the information from the roommate's partial recantation could be obtained elsewhere, and that the stipulation offered to Honstein solved the problem.

Honstein, meanwhile, argued that the trial court rightly decided the prosecutor was the only witness to the recantation, and that he had no obligation to accept the stipulation instead of the prosecutor's live testimony.

While justices agreed there was no case law to support forcing Honstein to accept the stipulation, he didn't have a compelling and legitimate reason to force the prosecutor to testify, because "the existence of a comparable alternative source is enough to render the prosecutor's testimony needless," Justice Boatright wrote.

Honstein could get the same information from the investigator who heard the roommate partially recant three days after the prosecutor, justices found, noting that the only differences were the roommate's offer in the first conversation to shave her head to reveal the mark from the soda can, and her explanation in the second conversation about mistaking the impact from the can for being punched.

"Though the two conversations were distinct, the second conversation provides all the relevant information found in the first," Justice Boatright wrote. And if the roommate doesn't deny changing her story, there's no good reason to have the prosecutor or investigator testify, he added.

"In sum, the facts of this case don't require us to blur the line between advocate and witness," Justice Boatright wrote. "Accordingly, we conclude that Honstein has failed to demonstrate a compelling and legitimate reason for the participating prosecutor to testify."

Adam D. Kendall of the 20th Judicial District Attorney's Office lauded the decision in a statement provided to Law360 Monday.

"This decision will provide much-needed guidance to prosecutors and trial courts in Colorado," Kendall stated. "Further, the decision will ensure that trials move forward justly, fairly, and without the confusion that would be caused by a prosecutor unnecessarily taking the witness stand in a case they are handling. With this decision, this trial can now proceed without further delay."

Counsel for the Boulder County Court declined to comment. Counsel for Honstein did not immediately respond to a request for comment Monday.

The 20th Judicial District Attorney's Office is represented in-house by Adam D. Kendall and Michael T. Dougherty.

Honstein is represented by Elizabeth Frawley, Elizabeth Califf and Megan A. Ring of the Office of the Colorado State Public Defender.

The Boulder County Court is represented by Emily Burke Buckley and Philip J. Weiser of the Colorado Attorney General's Office.

The case is In re: The People of the State of Colorado v. Harold Lloyd Honstein, case number 23SA271, in the Colorado Supreme Court.