Basic Cause-in-fact test: “But-For” Causation - Cause-in-fact asks the historical question, was the defendant’s conduct something that was a cause of the plaintiff’s injury. Note that the quality of the defendant’s conduct has no bearing on this question.

An actor’s conduct is the cause-in-fact of someone’s injury if we can say that “but for” the actor’s conduct the injury would not have occurred. In other words, the test asks: “if we could go back in time and remove the actor’s conduct, would that have prevented the injury?”

.................................................................................................................
This content is drawn from our Torts Negligence Tutorial 5: Causation-in-Fact, which contains numerous interactive and visual hypotheticals on the topic. If you are interested in this content, you may want to try our free Torts Advisor Course. You will need to register for our free account. It's fast, easy and, of course, free.
.................................................................................................................

Causation in Fact: “But-For Causation: Example # 1 - The operator of a large building unreasonably fails to install an aircraft warning beacon on the building’s roof. If a plaintiff slips and falls in the lobby of the building, and shows that the operator was unreasonable in failing to install the beacon, should that negligent conduct support recovery of damages by the plaintiff?

No. There is no causal link between the two events: conduct that endangers aircraft and a plaintiff’s slipping and falling in the building lobby.

Causation in Fact: “But-for Causation: Example # 2 - A driver drove thirty miles over the speed limit in a residential neighborhood for about two miles. Then the driver began to drive at a proper rate of speed. A few minutes later, the driver hit a pedestrian who was crossing a street. Was the driver’s conduct in driving over the speed limit a cause in fact of the pedestrian’s injury?

Yes. If the driver had obeyed the speed limit the driver would not have been at that location at the time the pedestrian was crossing the street. If we could go back in time and remove the questioned conduct (speeding), the injury would not have occurred.

Multiple But-For Causes An event can have many but-for causes. Many events may satisfy the but-for test for cause-in-fact with relation to a single injurious event.

Multiple Sufficient Causes: “Substantial Factor Test”: - In some unusual cases, multiple acts are causes of an injury, but the but-for test would not treat them as causes-in-fact. The classic example is “twin fires,” where one negligently-caused fire blends with a second negligently-caused fire and the resulting fire damages a plaintiff’s property.

Would the property have been all right if the first fire had not occurred? The answer to that question is “No,” so the but-for test fails to characterize the first fire as a cause-in-fact of the property loss. Interestingly, the but-for test produces the same answer with regard to the second fire.

Neither fire is a cause-in-fact of the property loss using the but-for test. In cases of this kind, courts treat cause-in-fact as established if it seems as though each act is a significant cause of the harm. This approach is called the “substantial factor” test.

For these and other topics, go to The Law School Experience.