The Colorado Supreme Court ruled on Monday that experts may, in certain situations, tell jurors whether child witnesses exhibited signs of being coached by adults, without running afoul of the general prohibition on witnesses testifying about the truthfulness of other witnesses.

The majority in the 4-3 decision maintained that defendants will not “open the door” to an expert’s opinion simply by challenging a child victim’s credibility. Instead, an expert’s comments about coaching were appropriate in the case of Gustavo Lopez because the defense had repeatedly advanced the idea that the child victims’ testimony reflected coaching by an adult.

“But that was only part of the story: the defense’s telling,” wrote Justice Carlos A. Samour Jr. in the April 13 opinion. The expert’s contrary testimony about coaching “didn’t weaponize the door kicked open by the defense.”

Chief Justice Monica M. Márquez, in dissent, believed the majority had erased the line preventing witnesses from opining about the truthfulness of other witnesses. Further, the prosecution had ample opportunity to address the defense’s coaching argument without the expert witness’s commentary.

“Coaching is a common defense to allegations of sexual assault on a child, and the majority’s decision today undercuts any such defense,” Márquez wrote for herself and Justices Brian D. Boatright and Susan Blanco. “A defendant who seeks to defend against allegations of sexual assault on a child by explaining that a third party improperly induced the child’s outcry may now anticipate the introduction of expert testimony vouching for the child’s truthfulness.”

Lopez stood trial in Boulder County in 2019 for multiple child sex assault-related charges against three victims who were his relatives. Jurors found him guilty, and he received an indefinite prison sentence of at least 50 years.

There was no physical evidence of the crimes, and the victims’ stories had many inconsistencies. Jurors also heard that some of the children wanted to live with their grandmother, who did not like Lopez.

During the trial, the defense suggested that family members can “influence” children into believing “something that’s not true.” Lopez’s counsel also suggested the victims’ stories changed during the time spent with their grandmother.

Jurors heard testimony from Kim Grimm, a forensic interviewer who talked to two of the victims in recorded conversations. She described multiple tactics professionals use to discern if a child has been coached, including asking for details about their experience. At the end of Grimm’s testimony, the jury had a question for her: “In your expert opinion,” the question read, were the children’s behaviors “consistent with interviews where coaching was present?”

Over the defense’s objection, the trial judge allowed her to answer. Grimm said she did not “feel like I saw huge red flags with that or anything.”

On appeal, a three-judge panel for the Court of Appeals acknowledged witnesses may not testify about others’ truthfulness on specific occasions. However, wrote Judge Elizabeth L. Harris for herself and Judge Lino S. Lipinsky de Orlov, the defense had opened the door by arguing the victims were influenced by an adult.

Although Harris stressed the ruling was “narrow,” Judge Timothy J. Schutz dissented, believing the panel had itself opened the door to experts vouching for victims’ credibility in numerous sex abuse cases.

“In the typical case involving allegations of sex assault on a child, the defendant must either contest the veracity of the alleged victim or effectively confess,” Schutz wrote. “But the logical extension of a broad ‘opening the door’ rationale would permit an expert to opine whether the accusing witness was being truthful every time a defendant suggests that an accuser was coached.”

The Supreme Court’s decision reflected a similar divide over how to handle the common claim that child witnesses have been coached.

Samour, in the majority opinion, noted that the concept of opening the door applies to evidence that would otherwise be inadmissible, as the purpose is to correct misleading impressions. He declined to say whether Grimm’s testimony was inadmissible, writing that Grimm had not actually testified about whether the child victims told the truth.

As for what Grimm did say, Samour outlined the numerous occasions during trial in which the defense tried to persuade jurors that the children’s grandmother had influenced their accounts of what happened. It was unsurprising, he wrote, that a juror eventually submitted a question about the subject.

“The jurors were almost invited to ask it. In essence, the juror’s question sought to have Grimm apply her generalized expert opinions — none of which the defense disputed — to the facts of the case, which is something expert witnesses are routinely permitted to do at trial,” Samour wrote. “And precluding Grimm from addressing the juror’s question would have given Lopez an unfair advantage by creating a misleading impression.”

Like the Court of Appeals’ majority, Samour cautioned that the ruling should be interpreted narrowly.

However, like Schutz’s dissent, Márquez doubted that it was possible.

“Put simply, the expert directly vouched for the children’s credibility,” she wrote. “I also find it especially troubling that the majority treats the theory of defense in this case as presenting a ‘misleading impression.’ I do not see how a garden-variety theory of defense centered on challenging the credibility of the allegations against the defendant constitutes ‘getting the upper hand at trial by selectively presenting facts.'”

Márquez added that, in her view, an expert could properly testify about the warning signs for a child who has received coaching. Jurors could then evaluate the circumstances themselves.

“But it was entirely improper for the expert to do the jury’s work for it,” she wrote.

The case is Lopez v. People.