To be guilty of negligence, a defendant in a lawsuit must breach that duty of care, and the breach of duty must be the cause of harm to the plaintiff.
The law looks at two types of causation—actual cause and proximate cause. Often, injury and harm is the result of a chain of events. The person who is the actual cause may or may not be legally responsible. Proximate cause is that act in the natural, direct, uninterrupted sequence of events without which the injury would not have occurred. Proximate cause seeks to decide who, in that chain of events, is responsible for the harm. This can get complicated.
First case: Henry runs the red light and, as a result, collides with Mary's car which is proceeding lawfully through the intersection, injuring Mary. Henry's negligence is both the actual and proximate cause of Mary's injury.
Second case: Henry is stopped at the red light. Marvin is talking on his cell phone and fails to stop his car, rear-ending Henry, and sending his car into the intersection where it collides with Mary's car, injuring Mary. Henry is the actual, but not the legal cause, of Mary's injury. Marvin's actions are the proximate cause of Mary's injury; his actions are the actual cause, sometimes called the "cause in fact", of the harm.
Susie Marks was seriously injured when the truck in which she was riding failed to negotiate a left turn. On the evening in question, Susie got a ride with Orson to the Elsewhere City Park, where she met her friend, Jerry, and his girlfriend, Kate. Orson said he would pick Susie up at 11:00 p.m. when the park closed. Jerry was a minor who had only been licensed to drive for a few