Canadian teacher Neil Bantleman is facing a 'very, very serious setback,' after Indonesia's Supreme Court handed down a decision the Canadian government has called "unjust," according to one legal expert. 

A three-judge panel overturned the acquittal of Canadian teacher Neil Bantleman on charges of sexually abusing children at a private school, and ordered him back to prison.

"This is a very, very serious setback for him for sure," said Kathleen Mahoney, professor of law at the University of Calgary.

According to Mahoney, the only remaining avenue for Bantleman is to seek judicial review of today's decision from judges at that same level of court.

"Judges on the same court are not usually excited about overturning their colleagues' decisions," Mahoney said.

"It would have to be a courageous judicial review judge that would do that. That's not to say it couldn't happen," but it would be "unusual," she said. 

Bantleman and his wife, Tracy travelled to the country to teach at an upscale private school with roughly 2,400 students, where he was accused of assaulting three kindergarten-aged boys between January 2013 and March 2014.

While he was originally convicted and sentenced to 10 years in prison, the Jakarta High Court overturned that decision in August 2015.

Today, the Supreme Court not only reversed the acquittal but increased the sentence to 11 years. 

Supporters in Calgary 'devastated'

Nancy McKellar who taught with Bantleman for five years at Webber Academy in Calgary said she was "devastated" by the news.

"I feel like I've been punched in the gut. My heart feels broken," McKellar said.

"We've supported him all along, we'll continue to support him and we'll make plans for whatever needs to be done next."

In a statement today, Canada's minister of foreign affairs St├ęphane Dion said the government was "deeply dismayed" by the reversal, calling it "unjust." 

McKellar said she was "heartened" by this "little glimmer of positivity," saying this response was "much stronger and much more prompt than we ever had from the previous government." 

Mahoney, however, said this kind of public criticism can cut two ways.

"Normally speaking, governments respect the judicial system of another country and try to find ways in which indirectly they can persuade perhaps a pardon at the end of the process," she said.

"Usually, if there's any sort of intervention, it's a back door kind of thing."