Even if jurors did speak among themselves during trial about a defendant’s guilt in violation of a judge’s instructions, legal rules prohibit the review of those allegations, the Court of Appeals ruled on Thursday.

“Courts have long been hesitant to peek behind a jury verdict by inquiring into a jury’s deliberations or its thought processes in reaching the verdict,” wrote Judge Stephanie Dunn for the three-member appellate panel. The judges determined the post-trial allegations of one juror about his fellow members’ misconduct did not fall into the accepted reasons for investigating verdict.

Stephen A. Saltzburg, a law professor at The George Washington University, said the Court of Appeals’ decision fit well within existing legal practice.

“The thing that courts look to are things that corrupt a jury verdict,” he said. If judges had to consider all allegations of jurors talking to one another about the case outside of deliberations, “every single verdict, just about, would be subject to being overturned.”

A Weld County jury found Sandra Archuleta guilty in 2017 of child abuse resulting in the death of her infant grandson. The four-month-old child, Donovan Archuleta, died in August 2015 with chemical burns on his face and in his mouth, a sepsis infection and broken ribs. A judge sentenced Archuleta to 24 years in prison. A separate jury convicted the child’s mother after she failed to get help for the baby.

At Archuleta’s sentencing hearing four months after her conviction, a male juror in her trial asked District Court Judge Julie C. Hoskins to impose the minimum sentence because he believed there was not evidence to convict her beyond a reasonable doubt. The defense later filed a motion for a new trial that elaborated on the alleged misconduct the juror witnessed.

Throughout the trial, Hoskins had instructed the jury to base its decision on the evidence it heard and the legal directives of the court. She also advised jurors not to discuss the case until they had all of the evidence. Yet, according to the unnamed juror’s recollection, he heard jurors talk about the evidence during breaks, and heard one person say the trial was taking too long because Archuleta was “overwhelmingly guilty.”

After listening to Archuleta’s police interview, “a number of jurors laughed and shook their heads,” and one asked, “Does she really expect us to believe that?” the unnamed juror alleged.

Under the Colorado Rules of Evidence, there is limited ability for a juror to question the validity of a verdict after the fact. Exceptions include the introduction of prejudicial information or outside influence, and if there was a mistake in filling out the verdict form. The U.S. Supreme Court has also allowed racist motivations of a juror to be brought forward.

Finding the juror’s allegations did not fit into any of those categories, Hoskins denied the motion for a new trial.

Archuleta appealed, claiming the rules governing evidence do not apply to juror conduct before deliberations begin. However, a three-judge panel of the Court of Appeals disagreed with her, citing a 5-4 Supreme Court decision from 1987 blocking allegations that as many as seven jurors were drunk during a man’s criminal trial, and also consumed marijuana.

In the majority’s opinion, Justice Sandra Day O’Connor explained that “long-recognized and very substantial concerns support the protection of jury deliberations from intrusive inquiry.” Justice Thurgood Marshall, writing for the four dissenting members, believed drug use could easily fall under the exception for “outside influence.”

Even alleged mistakes are not grounds for reviewing a jury’s verdict: the Colorado Supreme Court decided in 2002 against admitting the affidavits of five jurors who appeared to misunderstand a judge’s instructions at the time of deliberation.

In Archuleta’s case, the juror who allegedly observed unsanctioned deliberations “could have reported his concerns about pre-deliberation chatter to the court during the trial. Had he done so, the trial court could have taken curative measures to address the concerns,” wrote Dunn for the appellate panel.

She added: “To be sure, such pre-deliberation discussions — if they occurred — undoubtedly violated the court’s instructions and were inappropriate.”

Saltzburg, the law professor, said jurors are human, however, and it would be unrealistic to expect them to suppress all reactions to what they hear at trial.

“There’s nothing more unnatural than sitting together with a group of people for hours or days or weeks and not in any way even mentioning what you’ve been doing together. It’s not the way humans react. And courts have known that now for decades, maybe even centuries,” he said.

Saltzburg mentioned an exception to the prohibition on premature jury deliberations: in 1995, the Arizona Supreme Court allowed jurors in civil trials to talk about the evidence while the trial was ongoing.

The case is People v. Archuleta.