Proximate Cause

Raise your hand if you perfectly understand proximate cause (aka “legal cause”). No one? Read to the end as I explain how this concept works and how to use it on an exam.


In every tort, a plaintiff must prove that the defendant was not only the actual cause of the injury, but also the proximate cause of the injury. Proximate cause requires the plaintiff’s harm to be a reasonably foreseeable consequence of the defendant’s wrongful action. In a negligence case, there must be a relatively close connection between the defendant’s breach of duty and the injury.

Proximate cause is sometimes difficult for students to grasp. Why? Because it can be used to eliminate liability for a negligent defendant who caused the harm to the plaintiff. You are probably asking: why would the law eliminate liability for someone who was at fault in causing the plaintiff’s injury? In very rare cases, the events leading to the injury are freakish, remote, or improbable; or, there may be a superseding intervening event that injured the plaintiff. In these cases, the defendant is not the proximate cause of the injury, even though all the other elements are met.  (See my video on intervening causes for a more in-depth explanation on unforeseeable intervening events).

When deciding if someone is not the proximate cause of an injury, the law looks for an unforeseeable type of injury or superseding intervening event. A superseding intervening event is another term for an unforeseeable intervening event. When examining an unforeseeable type of injury, the law ignores the unforeseeable manner or extent of injury.

Rat on Fire

For example, in one case, the owner of a building negligently maintained an exposed pilot light, which had the potential to cause a fire. One would have expected the carpet or someone’s clothes to catch on fire, but instead, in this case, a rat ran by the exposed flame, its fur caught on fire, it ran into a hole, and the building caught on fire, causing damage to the plaintiff’s property in his apartment.

Now, though the manner of how the building caught on fire was unforeseeable, it was still a foreseeable consequence that the owner’s negligence would result in a fire. Therefore, the owner was the proximate cause of the fire.

Eggshell Plaintiff

Also, the law ignores the unforeseeable extent of injury in what is called the eggshell plaintiff rule. For example, if someone negligently backs into the car of a 95-year-old, causing her outrageously high medical bills, the defendant is still the proximate cause of the injury. You take the plaintiff as you find them.

In real life, plaintiffs prove proximate cause 99.99% of the time. In other words, proximate cause isn’t difficult to prove. So why do we spend so much time discussing a topic that has so little real-world application? Because proximate cause is the darling of law professors and bar examiners! For a more detailed discussion, you can read the proximate cause article by Professor Paul Hayden.

Example: Boiling Enamel

Cauldron. Used in proximate cause hypothetical

Let’s work through a fact pattern. Duffy is in the road construction business, and uses boiling enamel as part of the construction process. Duffy sets up a cauldron near a busy road, but he fails to set up any barriers in front of the boiling enamel. He also fails to place a person in front of the enamel to direct traffic away from it.

For the first element in a negligence action, Duffy had a duty to act reasonably under the circumstances. Second, Duffy breached his duty because a reasonable person would have taken a few basic precautions. For example, he should have placed a barrier around the boiling enamel. Also, he should have had people with flags on the road to get people to slow down. Under these facts, Duffy clearly acted unreasonably.

Suppose though that instead of a car crashing through and hitting the enamel, we have an airplane with engine problems. Pilot sees the road and decides to land. He lands at a point near Duffy, at which point the boiling enamel splashes on Perry. Under these facts Duffy isn’t the proximate cause of the harm because the airplane was a superseding intervening event that broke the causal link.

Foreseeability is the Norm

In real life, injuries are almost always a foreseeable consequence of the negligent conduct. If someone is speeding down the road, the foreseeable consequence is an injured pedestrian or another car. When a waiter fails to clean up a water spill, it’s reasonably foreseeable that someone is going to fall. Or, if an airplane mechanic fails to put enough oil into an airplane’s engine, it’s reasonably foreseeable that the plane will crash. It is only in strange cases, like Palsgraf v. Long Island Railroad where foreseeability becomes an issue.

Exam Tip

On an exam, always mention proximate cause in its own paragraph after you establish actual cause. When the harm is foreseeable, three to four sentences will suffice. But if the fact pattern deals with an unforeseeable type of harm or unforeseeable intervening event, then you need to discuss proximate cause in more detail. Don’t forget that reasonable minds can differ in these cases. So pick one side or the other and explain why you believe the defendant is or is not the proximate cause.

If proximate cause is still confusing, our tutors are available to help you master this difficult concept. If you want to explore this complex area, read Causation in the Law by H.L.A. Hart.

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Proximate Cause