Seat belt defense applicable when seatbelts not required
I have 2 children, riding in the back of a 15 passenger van on a ski trip, who were injured (brain damage and borken pelvis) in a rollover accident 60 mi E of Denver on I-70. Insurance says pain and suffering not compensable because they did not have their seat belts on. Colorado law does not require back seat passengers to wear seat belts. Is the 'seat belt defense' applicable to these kids? Does insurance co have to demonstrate that belts were available and working properly, or just that they weren't used?