Car doors are supposed to keep us safe -but sometimes they can be highly dangerous.
The drag of a passing vehicle or a strong gust of wind can whip a slightly open door into the path of another car, or someone’s face, or inwards onto the fingers of a child (this says nothing about the damage to the car caused by doors being snapped backwards and forwards).

Today’s invention is a relatively simple modification to car doors. It is an internal locking mechanism which only allows the door to be moved when the handle is being held in the open position.
This might best be implemented as a frictional brake device, located at the hinge axis. A similar approach might be applied in domestic doors to lessen the chance of crushing children’s fingers in the hinged edge.