The Colorado Supreme Court ruled on Monday there is no automatic reversal of a defendant’s convictions if jurors rely on instructions that outline a different crime than the one prosecutors charged in the first place.

The justices concluded that such a change, known as a “constructive amendment,” does not fall in the category of structural error that affects the fundamental fairness of a criminal trial. Instead, constructive amendments can benefit the prosecution, the defense or neither side, depending on the circumstances.

In the underlying case out of Weld County, Jamie Edward Bock is serving 20 years in prison after a jury convicted the contractor in 2019 of taking money from clients without performing work.

Prosecutors charged Bock under the portion of Colorado’s theft law that criminalizes intentionally obtaining something of value from another person through deception. But at trial, the prosecution offered jury instructions cobbled together from a different part of the law that permits “aggregation” of theft offenses into a single charge with a more serious penalty.

Then-District Court Judge Thomas J. Quammen gave the hybrid instruction and the defense did not object.

After Bock’s conviction, a three-judge panel of the Court of Appeals considered whether the constructive amendment harmed the defense. By 2-1, the panel said it did not.

The majority noted the defense had requested, and prosecutors provided, a list before trial of all the occasions on which Bock took money from his victims — with each victim or set of victims falling under a single theft count. Therefore, wrote Judge Craig R. Welling for himself and Judge Jerry N. Jones, the defense was aware of all alleged thefts and the prosecution actually created a higher burden for itself to prove all of them.

Judge Timothy J. Schutz, however, was unconvinced. Specifically, he observed the jury instructions contradicted themselves — referencing a six month window for the thefts, but also inviting jurors to consider Bock’s actions in a much wider timeframe. More broadly, aggregating the charged offenses would have affected Bock’s defense strategy in ways the appellate court could not predict. For example, Bock might have focused on disproving just one of the thefts at trial.

Bock appealed to the Supreme Court to review the appellate panel’s conclusions.

“The charging instrument is the most important document in a criminal proceeding. It drives the entire case — from whether the defendant pleads guilty or goes to trial, through the selection and presentation of evidence, all the way to the final jury instructions,” wrote public defender Chelsea E. Mowrer. “When the jury is instructed on something different, counsel essentially went to trial on a different case.”

The government acknowledged the prosecution never formally amended its charges against Bock to reflect it was pursuing an aggregation theory under a different portion of the theft law. But the Colorado Attorney General’s Office argued the defense was clearly aware before trial how prosecutors intended to pursue their case.

The Supreme Court, in a Sept. 9 opinion, concluded for the first time that constructive amendments are not structural errors that always require a reversal of convictions.

“For instance, a defense could apply equally to the charged and amended counts. Or a constructive amendment can make the prosecution’s case harder to prove,” wrote Justice Melissa Hart. “In these circumstances, the constructive amendment does not necessarily make the criminal trial unfair.”

The court sided with the government and the appellate panel’s majority, noting the prosecution’s own instructions in this instance raised the burden of proof for a conviction.

The case is Bock v. People.