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Types of Causation in a Personal Injury Case

— January 24, 2022

Establishing causation is crucial in a personal injury insurance claim or lawsuit.

According to Black’s Law Dictionary, causation is defined as “whether an act or omission was responsible for something occurring or not occurring. The relationship of cause and effect of something happening or not happening.” Under the law, causation is further defined into two specific types: cause-in-fact and proximate cause. This concept is critical in a personal injury claim based on negligence. An injured plaintiff must establish four elements to succeed in a personal injury claim: duty, breach, damages, and causation. The defendant’s actions or failure to act must have caused the plaintiff harm. To prove this element, evidence is required to sufficiently demonstrate each type of causation.

Causation in a Personal Injury Lawsuit

When someone is hurt or injured because of another person, company, or entity’s negligence, they have the right to pursue economic and non-economic damages through a personal injury claim. To prevail in a personal injury lawsuit, an injured plaintiff must prove several elements to establish that the defendant’s conduct or omissions were negligent. More specifically, the plaintiff must show that the defendant’s breach of duty was the cause-in-fact and proximate cause of their injuries.


Cause-in-fact is also known as “actual cause.” For someone without any legal knowledge, actual cause is a straightforward concept. For example, if a truck drives through a red light and collides with a car, the truck driver’s actions are the cause-in-fact. 

Proximate Cause

Proximate cause, unlike actual cause, is a much more complex legal concept. Proximate cause only exists if a plaintiff’s injuries were foreseeable. A defendant must have had a reasonable belief or reasonably anticipated that their conduct or lack of action could result in injuries to another. For instance, a reasonable person could foresee that driving home from a party when drunk could result in a serious accident.

In a personal injury lawsuit, a defendant is typically not held liable for injuries that were not reasonably predictable or linked to their actions or decisions.

To illustrate this, imagine the following chain of events. The defendant runs a red light. To avoid the oncoming car, another driver swerves and crashes into a construction site. A shed storing hazardous chemicals is smashed in the ensuing collision, starting a fire at the construction site. The flames are infused with hazardous chemicals. Nearby neighbors develop serious physical symptoms because of the chemicals they breathe.

Fire; image courtesy of Hans via Pixabay,

While the driver who ran the red light could be held liable for any injuries to the motorist who acted to avoid an accident, they might not be responsible for the people who were sickened by the fire because those specific injuries were unpredictable given the negligent conduct.

The “But For” Test

Some jurisdictions employ the “but for” test to determine if a defendant’s conduct caused the event that resulted in the plaintiff’s injury. Under this test, a simple question is asked, “would the accident or incident have occurred but for the defendant’s actions or omission?” If a jury or judge determines that the injury would not have happened save for the defendant’s conduct, the required element of causation is established.

For instance, a drunk driver is speeding through a crowded shopping area and strikes a pedestrian crossing a street. The accident would not have occurred if the driver had not operated their vehicle while under the influence. This example also satisfies proximate cause because it is reasonably foreseeable to cause an accident if you are driving drunk.

To further illustrate this concept, imagine the same drunk driver crashes into a stack of propane stored outside a hardware store — the ensuing explosion injures several pedestrians who were walking a block or two away. The explosion would not have happened “but for” the motorist driving drunk. However, because the explosion harmed the pedestrians, the driver might not be held liable because it could be argued that such injuries were not foreseeable.

The “Substantial Factor” Test

Other jurisdictions employ the “substantial factor” test when determining causation in an injury case. The court will determine if the defendant’s conduct was a substantial factor in causing the plaintiff’s injury. A substantial factor is defined as something that contributes materially to the incident, event, or injury. To be a material contribution, the effects of the conduct must still be in effect at the time of the injury. If a defendant’s actions or omissions only trivially impacted the event or injury, then they are likely not a substantial factor.

For example, a distracted driver collides with a truck containing toxic materials. The crash’s impact exposes the truck driver to these materials, causing life-threatening chemical burns. In this case, the driver’s actions would be a substantial factor in the truck driver’s injuries. The effect of the driver’s actions is still in operation at the time of the toxic spill.

Now imagine a slightly different fact pattern. The distracted driver swerves into the truck’s lane. To avoid an accident, the truck driver quickly turns their rig, losing control and jackknifing on the roadway. The crash results in toxic chemicals spilling onto a sidewalk, injuring several pedestrians walking along the sidewalk. In this case, the driver’s actions might not be a substantial factor in the injuries the pedestrians suffered.

An Experienced Personal Injury Lawyer Will Work to Establish Causation

Establishing causation is crucial in a personal injury insurance claim or lawsuit. In many cases, causation is straightforward and not difficult to prove. However, in many cases that go to trial, causation is heavily contested. An experienced personal injury lawyer will work to gather evidence to prove the defendant’s actions were the cause-in-fact and proximate cause of an injury.

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