(Reuters) - A former DuPont manager who stole trade secrets about the company's biofuels business for his new employer was properly sentenced to 42 months in prison even though the federal sentencing guidelines called for a term of zero to six months, a federal appeals court held Friday.

The 8th U.S. Circuit Court of Appeals rejected arguments by Josh Harry Isler's appellate lawyers at Winston & Strawn, who said the trial judge in Cedar Rapids, Iowa abused her discretion by departing from the guidelines after she concluded that the damage to DuPont could not be calculated "with any degree of accuracy."

Isler argued that the government's failure to establish the amount of DuPont's loss meant the judge had to treat the loss as $5,000, the figure he had acknowledged in his plea agreement. The 8th Circuit disagreed.

"Here, the district court's upward variance was clearly motivated by its conclusion that the Guidelines range underrepresented the seriousness of the offense," Circuit Judge Bobby Shepherd wrote, joined by Circuit Judges James Loken and Ralph Erickson.

Isler's attorneys did not immediately respond to requests for comment on Friday. The U.S. Attorney's Office in Cedar Rapids also had no immediate comment.

According to the opinion, Isler was working as a technical service account manager at DuPont Industrial Biosciences in 2013 when he was approached by one of the company's smaller competitors.

Isler accepted an employment offer from the new company in August 2013 and gave DuPont two weeks' notice. Shortly after accepting the offer, he received a text from that company's COO, seeking information about ethanol plants Isler worked with at DuPont.

Over his final two weeks at DuPont, Isler downloaded "hundreds of internal electronic files belonging to DuPont to an external media device folder" and emailed DuPont's visitor logs to another employee at the new company, the 8th Circuit said. And, once employed at the new company, he "immediately assumed a role of providing information and advice regarding DuPont's proprietary information and customers."

An FBI investigation ensued. Isler denied any significant downloading until he was confronted with evidence that he had done so. He later said the downloads were a common practice that DuPont had encouraged.

In June 2018, Isler agreed to plead guilty to one count of trade-secret theft and one count of making false material statements to the FBI. In his plea agreement, he admitted that the loss was "at least $5,000" but acknowledged that the total would be determined by the sentencing judge.

At sentencing, the government argued that DuPont could have lost "thousands, if not millions" of dollars in research and development costs, or as much as $18 million in lost sales. U.S. District Judge Linda Reade rejected both measures but said the loss was clearly significant, and considered other factors – including Isler's knowledge and understanding of his confidentiality agreement with DuPont, his apparent "minimization" of his wrongdoing, and a minor criminal history – before imposing the 42-month sentence.

Affirming under a deferential standard of review, the 8th Circuit said Reade had considered Isler's arguments, explained her reasons for rejecting them, and "merely imposed a fact-specific sentence after considering the unique circumstances of this case."

The case is United States v. Josh Harry Isler, 8th U.S. Circuit Court of Appeals, No. 19-1891.

For the United States: Assistant U.S. Attorney Richard Murphy

For Isler: Sean Suber and Linda Coberly of Winston & Strawn