Proximate Cause vs. Actual Cause: What's the Difference?

To win a negligence claim, the plaintiff must prove both actual cause (also called cause-in-fact or factual cause) and proximate cause (also called legal cause). They are separate elements, and both must be satisfied. Think of actual cause as “did the defendant's conduct cause the harm?” and proximate cause as “should the defendant be held legally responsible for it?”

The standard test for actual cause is the but-for test: But for the defendant's negligent conduct, would the plaintiff's injury have occurred? If the answer is no — the injury would not have happened without the defendant's conduct — then actual cause is established.

Example: But for the driver running the red light, the pedestrian would not have been hit. Actual cause: satisfied.

Proximate cause limits liability to consequences that are reasonably foreseeable. Even if the defendant actually caused the harm, they may not be liable if the harm was too remote, too bizarre, or too unforeseeable.

The landmark case is Palsgraf v. Long Island Railroad: the railroad employee's negligence in pushing a passenger caused a package of fireworks to explode, which knocked over scales that injured Mrs. Palsgraf. The majority held the railroad owed no duty to Palsgraf because her injury was not a foreseeable consequence of the employee's conduct.

An intervening cause is an event that occurs between the defendant's negligent act and the plaintiff's injury. If the intervening cause is foreseeable, the defendant remains liable. If it's unforeseeable and extraordinary, it may become a superseding cause that breaks the chain of proximate causation.

Example: D negligently leaves a car unlocked with keys in it. A thief steals the car and injures P. Is D liable? Most courts say yes — car theft is foreseeable.

On a torts exam, analyze causation in two steps:

1. Actual cause: Apply the but-for test. If multiple causes, consider the substantial factor test.
2. Proximate cause: Was the type of harm foreseeable? Were there intervening causes? Were they foreseeable or superseding?

Always discuss both. Students who skip actual cause or conflate the two lose points.