Saskatchewan's highest court is not toughening the sentences of three men involved in what's been called the biggest drug trafficking case in provincial history.

The Saskatchewan Court of Appeal said in a written decision Wednesday that it has dismissed an appeal by prosecutors who wanted longer sentences for Brock Palfrey, William Larsen and Troy Swanson.

"I conclude ... that the global sentences imposed by the sentencing judge were not demonstrably unfit," chief Justice Robert Richards wrote on behalf of the court.

"As a result, I would not give effect to the Crown's request to make them more severe."

Court documents say Palfrey orchestrated the movement of cocaine for drug traffickers across remote locations on the Saskatchewan-Montana border and then transported the drugs to British Columbia. Larsen and Swanson were drivers who were paid between $5,000 and $10,000 per trip.

"Overall, this is described by the Crown as the biggest drug trafficking case in Saskatchewan history and one of the most significant in national history," read the decision.

Palfrey, who is from Vernon, B.C., pleaded guilty to being a member of a criminal organization and to instructing another person to commit the crimes of importing cocaine, exporting ecstasy and possessing those drugs for the purpose of trafficking. He also pleaded guilty to trafficking in cocaine, trafficking in ecstasy, breaches of recognizance and conspiracy to traffic in cocaine.

Larsen pleaded guilty to importing cocaine, possessing cocaine for the purpose of trafficking, exporting ecstasy and possessing ecstasy for the purpose of trafficking.

Swanson pleaded guilty to importing cocaine and possessing cocaine for the purpose of trafficking.

Palfrey was sentenced to 18 years in prison, Larsen to a term of 12 years and Swanson to 11 years.

The Crown appealed the sentences and asked that they be substantially increased. Among other things, the Crown argued that the sentencing judge made several errors, including under-valuing the gravity of the offences.