When rear-hinged doors were invented, seat belts were not yet in use. Furthermore, anyone grabbing one of these doors if it flew open while the car was in motion was at great risk of falling out of the car. The door itself was more prone to flying open at speed due to the rear hinge and basic physics. Opening this door in a busy street also increases the injury risk to a passenger if another car hits the door, as the door itself could crush the occupant. All these reasons and the greater risk of a fatality led to the dark nickname, ‘suicide doors’.