Cause in Fact
Cause in fact, also called actual cause, is the bridge between the defendant's breach and the plaintiff's harm.
8. Negligence: Cause in Fact
The causation element for negligence requires a showing that the defendant’s conduct was an actual cause (cause in fact) of the harm to the plaintiff.
- Actual cause (cause in fact) is a required element of negligence liability. This element is also required for intentional torts and strict liability (discussed further below in concepts 13-19).
- The but-for test is the usual manner in which actual cause is established, meaning that the injury would not have happened but for the defendant’s conduct. Or, said differently, in the absence of the defendant’s conduct the injury would not have happened anyway.
- An alternative test of actual causation, the substantial factor test, permits cause-in-fact to be established even in the absence of “but for” causation.
- The substantial factor test may be used in situations of multiple causes, including successive causes and multiple causes in which any one of the causes would have been sufficient.
Cause in fact asks a factual question: did the defendant's conduct actually help bring about the harm? The default tool is the but-for test, with the substantial factor test as the backup for multiple sufficient causes.
Cause in fact, also called actual cause, is the bridge between the defendant's breach and the plaintiff's harm. It asks a factual question, not a fairness question: did this conduct really help bring about this injury?
The usual tool is the but-for test. You mentally erase the defendant's conduct and ask whether the injury still happens. If the injury would not have happened without the conduct, the conduct is a but-for cause. If the injury would have happened anyway, the conduct is not an actual cause, and the negligence claim fails on causation no matter how careless the defendant was.
There is one situation the but-for test cannot handle: two or more separate causes, each of which on its own was enough to produce the harm. Erase either one and the injury still happens, so but-for would clear both defendants even though together they plainly caused the harm. To avoid that gap, courts switch to the substantial factor test, which treats a defendant as an actual cause whenever the conduct was a substantial factor in bringing about the harm. The substantial factor test is the backup that fills the hole in but-for; it is used for multiple causes, including successive causes and multiple sufficient causes.
"Erase it and see." Mentally delete the defendant's conduct.
If the injury still happens, the conduct is not a but-for cause.
If the injury disappears, it is.
"Two guns, one victim." When two separate causes are each enough on their own, but-for lets both off the hook (erase one, the other still kills).
That is your signal to switch to substantial factor, which holds each one in.
But-for is the default.
Multiple sufficient causes break but-for, so reach for substantial factor.
A patient arrives at an emergency room with chest pain. The on-call physician negligently fails to order a standard test and sends the patient home, where the patient dies of a heart attack hours later. The estate sues the physician for negligence and must prove actual cause.
Suppose the expert testifies the condition was already fatal and no treatment, however prompt, could have changed the outcome.
Imagine two independent fires, each large enough on its own to burn the plaintiff's barn, that merge and destroy it.
An option in a cause-in-fact question turns on whether the harm was foreseeable, or on an intervening or superseding cause.
Foreseeability and superseding causes are proximate cause. Cause in fact is purely factual: did the conduct make a difference to the harm? Keep the two causation questions separate.An option says the defendant 'created a risk' or 'could have caused' the harm, or applies plain but-for to two independently sufficient causes and clears everyone.
Creating a risk is not actual causation; run the erase-and-see test on the harm that actually occurred. With multiple sufficient causes, switch to the substantial factor test.An option rides on the defendant's intent, the degree of carelessness, the level of duty, or a procedural point like failing to join another tortfeasor.
None of those answer the actual-cause question. Ask only whether the conduct was a cause in fact of the harm.An option treats being first in time (or last in time) as what establishes actual cause among successive causes.
Order in time is not the trigger. The substantial factor test asks whether the conduct meaningfully contributed to the harm, not which cause came first.the stem hands you conduct that was careless and an injury, and the call asks whether the conduct was "an actual cause" or "a cause in fact" of the harm, or whether the harm "would have happened anyway." Your first move is the erase-and-see test: delete the defendant's conduct and ask if the same injury still occurs.
Watch for two tells.
language like "the injury would have occurred regardless" is steering you toward a no-actual-cause answer.
when the facts give you two or more separate causes that were each independently enough to produce the harm, the question is almost certainly testing substantial factor, so do not let plain but-for trick you into clearing everyone.
And if the call mentions foreseeability, an intervening act, or a superseding cause, the question has moved to proximate cause, not cause in fact.
A hospital nurse negligently failed to check on a patient for several hours after surgery. During that time the patient died. The patient's expert later testified that the patient died from a sudden, undetectable clot and that even hourly monitoring by the nurse could not have detected the clot or prevented the death. The patient's family sued the nurse for negligence.
Was the nurse's failure to monitor an actual cause of the patient's death?
A landlord negligently failed to repair a broken stair railing despite repeated complaints. A tenant carrying groceries lost her balance on that staircase, reached for the railing, and fell when it gave way, breaking her arm. Evidence showed that a sound railing would have held her weight and stopped the fall.
Was the landlord's failure to repair the railing an actual cause of the tenant's injury?
Two campers in separate parts of a forest each negligently left a campfire burning. Each fire grew into a wildfire, and either wildfire alone would have been large enough to burn down a rancher's cabin. The two fires merged and destroyed the cabin together. The rancher sued one camper, who argued that his fire was not a but-for cause because the other fire would have destroyed the cabin anyway.
Can the rancher establish that the sued camper's fire was an actual cause of the cabin's destruction?
A delivery driver negligently ran a red light and clipped a cyclist, knocking him to the ground with a minor scrape. As the cyclist lay in the road, a speeding car that no one could have anticipated swerved around the corner and struck him, causing serious injuries. The cyclist sued the delivery driver. The parties dispute only whether the delivery driver's conduct was an actual cause of the serious injuries.
Was the delivery driver's negligence an actual cause of the serious injuries?
A homeowner negligently let a backyard pool's safety gate fall into disrepair so that it no longer latched. One afternoon a neighbor's child climbed over the four-foot fence, bypassing the gate entirely, and was injured in the pool. Evidence showed the child never went near the broken gate and would have climbed the fence regardless of whether the gate latched. The child's parents sued the homeowner for negligence.
Was the homeowner's failure to repair the gate latch an actual cause of the child's injury?
A pedestrian was struck by a negligent motorcyclist, suffering a deep leg wound. Minutes later, before any treatment, a negligent ambulance driver collided with the stretcher and aggravated the same wound so severely that the leg could not be saved. Either impact, standing alone, would have been enough to cause the loss of the leg. The pedestrian sued the motorcyclist, who argued the ambulance driver's later conduct meant his own conduct was not a but-for cause.
How can the pedestrian establish that the motorcyclist's conduct was an actual cause of losing the leg?