The legal theory is similar to the captain of a boat or pilot of an aircraft. In essence, the driver is responsible for the safety of his passengers. As such, the driver should have made sure that he was properly secured in his seat before driving off.
Taxcontrol...to begin with there are NO seats in these transport vans....it is a metal bench with a solid metal divider separating the two benches....it is pretty compact and as a person who has ridden in these types of transport I can honestly say you really have to go out of your way to get hurt in these vehicles. There are no seat belts or restraining belts..they are made this way for a reason, that being so no lunatic can fashion any type of weapon that may hurt an officer or another prisoner....you would not believe what some people who are incarcerated will think of....
Meanwhile we put our little kids on school buses every morning that don't have seat belts.