Causation in Personal Injury Lawsuits

When a person is injured due to another person’s or entity’s negligence, he or she can recover economic and noneconomic damages that flow from the negligence. Among the elements that the plaintiff suing for negligence will have to prove is that the defendant’s violation of a duty was the actual and proximate cause of his or her injuries. He or she will also have to prove duty, breach of duty, and damages.

Actual cause, also known as “cause in fact,” is straightforward. When a bus strikes a car, the bus driver’s actions are the actual cause of the accident. Proximate cause means “legal cause,” or one that the law recognizes as the primary cause of the injury. It may not be the first event that set in motion a sequence of events that led to an injury, and it may not be the very last event before the injury occurs. Instead, it is an action that produced foreseeable consequences without intervention from anyone else. In other words, the plaintiff will have to show that the injuries were the natural and direct consequence of the proximate cause, without which the injuries would not have occurred.

“But For” Test

Some states follow the “but for” rule to determine if an event caused the plaintiff's injury. This rule considers whether the injury would not have happened but for the defendant’s negligent action or omission. When there is a finding that an injury would not have happened but for a defendant’s action, it establishes the element of causation.

For example, when a drunk driver is weaving in and out of traffic and hits a pedestrian, causing massive hemorrhaging and brain damage, the accident would not have happened but for the drunk driver’s intoxication. It is foreseeable that if a driver is drunk and weaving through traffic, he or she may cause injuries to a pedestrian. However, a defendant cannot be liable for totally unforeseeable injuries. If the same drunk driver hits a warehouse full of explosives, and there is an explosion that causes drivers to rubberneck and hit the pedestrian, the drunk driving is probably not the cause of the pedestrian’s injuries.

“Substantial Factor” Test

Other states use the “substantial factor” test in connection with causation. Under this rule, the court will consider whether the defendant’s actions or omissions were a substantial factor in causing the injury. In jurisdictions that follow the substantial factor test, a substantial factor is one that contributes materially to the occurrence of an injury. An action contributes materially when its causative effects are in operation until the moment of injury. An act or omission that only trivially affects the occurrence of an injury is not a substantial factor and will not be considered the cause of the injury.

For example, if a distracted driver crashes into a truck carrying explosives, and as a result, the explosives explode and kill the truck driver, the distracted driving is a substantial factor in the accident. The distracted driver’s actions are in operation until the truck explodes. However, if a distracted driver crashes into a stop sign and in order to avoid the site of the accident, a tractor-trailer driver turning left swings particularly wide such that the portion of the truck carrying explosives hits a parked car and explodes, killing a passing pedestrian, the distracted driver’s actions affected the pedestrian’s death only incidentally, whereas the truck driver’s swinging wide turn is a substantial factor in his or her death.

Last reviewed October 2024