Judgement from an insurance company

6 years ago my son was involved in a serious car accident and him and his friend were injured. My son was at fault (DUI), and his car insurance had lapsed, therefore he had no insurance at the time.
His medical bills were paid through my health insurance and his friend's bills were paid through his parent's insurance. We were fortunate that the other family never sued us as they thought they were both a fault.
A year and a half later, his friend's insurance started sending my son letters asking him for $500,000 that they paid his friend. They sued him and sent him by mail a notice of the hearing. At the time my was in jail for a few months (because of the DUI) and sent them a statement notarized by one of the deputies indicating that he was incarcerated and cold not attend the hearing.
The hearing went through and a judgement was placed on my son's credit report. He has been out of jail, going to school (graduating with a Bachelor's Degree in October), has a fulltime job, but no license. His license was revoked for 5 years and just a couple of months ago, after a lot of meetings and hearings with the drivers licenses people, they have finally agreed to reinstate his license. He just has to have a letter from the insurance company indicating that they are willing to take payments on the $110,000 judgement they have against him. He has tried to contact them, but they want the amount in full.
Can that be done? He complied with their request by telling them that he was in jail at the time and could not attend the hearing, and they still had the hearing without him.
Does anyone know if he can appeal that decision?
Thanks.