Nico is a passenger in a car driven by owen, whose reckless driving causes an accident, injuring himself. nico, uninjured, accompanies owen to parkside hospital in an ambulance. the ambulance is hit by a car driven by quin, and nico is injured. nico files a suit against owen, alleging negligence. the element most likely to be a question for the court to decide is

I believe the answer is: Proximate cause
Proximate cause refers to and event that is not directly cause a harm to other, but it contribute to the primary cause of the harm.

Other example would be when you finished rearing a bike from a mechanic. When you cross the road, you notice that your brake is not working which lead to the crash between you and a car.

In this case, you can sue the mechanic for proximate cause