A Mesa County judge and prosecutors imposed an illegal sentence in a plea deal, prompting the Court of Appeals on Thursday to order a do-over.

The prosecution charged Robyn Lee Webber with multiple offenses from October 2013, including driving under the influence and vehicular eluding. They also sought to enhance his sentence based on his four prior felony convictions from 1997 onward.

Under the “big habitual criminal” statute, Webber would have been subject to a 12-year sentence, calculated by taking the maximum three-year punishment for his vehicular eluding crime and multiplying it by four. Colorado law allows for this enhancement if someone has at least three prior, separate felony convictions.

However, Webber pleaded guilty under the “little habitual criminal” statute, which imposed a nine-year sentence by taking the vehicular eluding punishment and multiplying it by three. In contrast to the “big habitual” provision, the court could only consider felony convictions from the previous 10 years.

The Mesa County District Attorney’s Office conceded on appeal that its prosecutor and District Court Judge Richard T. Gurley based the sentencing on two of Webber’s prior convictions that occurred outside of the 10-year window. Consequently, a three-member panel of the Court of Appeals deemed Webber’s sentence illegal, and was not a minor mistake.

“Under these circumstances, a reasonable person would have been induced to plead guilty to avoid an additional three years in prison,” wrote Judge Neeti Vasant Pawar in the panel’s July 22 opinion.

The court voided Webber’s plea and sentence and directed a reinstatement of Webber’s original charges.

District Attorney Daniel P. Rubinstein said he agreed with the appellate judges that the sentence used the wrong prior felonies, but noted the court’s decision means a 12-year sentence is now back on the table.

“Mr. Webber should be careful what he asks for because he is now facing more time,” Rubinstein observed.

The case is People v. Webber.