Proximate cause is an event that is sufficiently related to a harm, and an event considered to be a primary cause of that harm. In a personal injury lawsuit, the plaintiff must prove that the actions of the defendant were the cause of the harm suffered. In order to satisfy the legal requirement of cause, a plaintiff must show that the defendant's negligent actions were both the actual cause and proximate cause of the injury or damage suffered.
Actual cause is often referred to as but-for causation. An analysis of a but-for test might read: "It is likely that injury X would not have occurred but for the actions of person A." For example, if Driver A runs a red light and hits Driver B, injuring him, Driver A’s act of running the red light is the likely actual cause of Driver B’s injuries. In other words, Driver B would not have been injured but for Driver A's running the red light. However, actual causation can sometimes be quite broad, drawing otherwise unrelated events into the chain of causation. Because of this, proximate cause - the second type of causation - functions as a limitation.
While a particular act might be found to be the actual cause of an injury, that does not necessarily mean that it is also the proximate cause of that injury. In order for an action to be the proximate cause of an injury, the two must be related closely enough through the chain of causation that the act is considered the sufficient cause of the harm. The most common test for assessing this relationship is foreseeability. The question becomes whether or not the harm that the plaintiff has suffered was a reasonably foreseeable outcome of the defendant's negligence. If so, than those actions are the proximate cause of the harm suffered; if not, no proximate cause exists.
A good illustration of this principle is as follows: A woman is pushing a baby carriage down the street when she witnesses Driver A's car accident with Driver B (described above). She is so distracted by the accident that she lets go of the carriage momentarily and it runs away from her, striking a pedestrian and causing him to fall, hurting his back. Using only an actual cause analysis, it is likely that Driver A is indeed responsible for the pedestrian's back injury. This is because but for Driver A's running the red light, there would not have been an accident in the first place. With no accident to distract the woman, she would not have let go of the carriage and so the pedestrian would never have been struck and never would have fallen. Yet there may not be proximate cause because a pedestrian getting hit by a baby carriage is probably not a foreseeable result of running a red light. Since there is not likely proximate causation, a court is not likely to find Driver A liable for the pedestrian’s back injuries.
The doctrine of proximate cause helps to limit the damage for which a defendant may be held accountable, making him liable only where his actions are both the actual cause of a reasonably foreseeable injury. It can be difficult to determine whether or not proximate cause exists, so contact an experienced personal injury attorney with any questions.