A Sixth Circuit panel on Tuesday affirmed that a Michigan man's 103-month prison sentence should not be shortened, despite a recent change to sentencing guidelines, because his modest rehabilitation was not enough to justify a reduction.

Marcus Gilbert was convicted on drug conspiracy charges and pled guilty to participating in a drug-trafficking organization. While incarcerated, sentencing guidelines were amended in a way that reduced his criminal-history score — used to inform recommended sentences — from category IV to III. The sentencing range for category IV is 100 to 125 months and is 87 to 108 months for category III. Because his 103-month sentence was still within the category III range, it did not change Gilbert's sentence but allowed him to file a motion requesting sentence reduction.

According to court documents, Gilbert said that had his starting category been III at the time of sentencing, he likely would have been dropped to category II by the sentencing judge. At category II, sentencing would be between 78 and 97 months.

The U.S. District Court for the Eastern District of Michigan denied Gilbert's motion, citing multiple prison disciplinary infractions that outweighed his modest rehabilitation gains. Gilbert appealed that decision to the Sixth Circuit, where the lower court's decision was affirmed Tuesday.

"In prison, Gilbert had trouble following the rules," the panel wrote in its judgment. "He amassed a long prison rap sheet for fighting, lying, smuggling, and other infractions."

Gilbert also was caught with a contraband cellphone and chargers while incarcerated.

The panel noted that Gilbert "showed some positive signs of growth" and completed his GED and took some additional classes.

The court is tasked with determining not only if Gilbert qualifies for a reduced sentence, but if such a reduction should be granted.

The Sixth Circuit panel agreed with the lower court's reasoning that "the presentation of a modest record of successful rehabilitation is not enough standing alone to warrant an upset of the original sentencing decision."

Gilbert contended that the lower court used the incorrect legal standard to make its decision, specifically that it used the statute for compassionate release and not release due to a retroactive change in sentencing guidelines. Again the Sixth Circuit disagreed and said the lower court used the correct legal standard.

"At every stage of its analysis, the court explained that it considered and rejected Gilbert's rehabilitation, not because rehabilitation doesn't count, but because Gilbert hadn't shown enough progress," the panel wrote.

U.S. Circuit Judges John B. Nalbandian, Whitney D. Hermandorfer and Eugene E. Siler Jr. sat on the panel for the Sixth Circuit.

Representatives for the parties could not immediately be reached for comment.

The government is represented by Benjamin Coats of the U.S. Attorney's Office for the Eastern District of Michigan.

Marcus Gilbert is represented by Benton C. Martin of the Federal Defender Office.

The case is United States of America v. Marcus Gilbert, case number 1742, in the U.S. Court of Appeals for the Sixth Circuit.

--Editing by Rich Mills.