Also known as: factual cause · factually cause · factually caused · factually causing · cause in fact · but-for causation · but for cause
Written by attorneys · grounded in primary & secondary sources — see below
The actual connection between a defendant's conduct and a plaintiff's harm under which the harm would not have occurred but for the conduct.
Fatima Flores was struck by a single bullet while hiking. Two hunters, each firing negligently in her direction, could not be distinguished as the source. Because the plaintiff could not identify which shot caused the injury, the court shifted the burden to each hunter to prove his shot was not the factual cause.
Felix Franco stabbed Freya Freeman during a robbery. She lingered for nineteen months before dying from complications. Even though the wound was a but-for cause of death, the common-law year-and-day rule barred homicide charges because the death occurred after the prescribed period.
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Faith Fitzgerald developed cancer decades after her mother took DES during pregnancy. Multiple manufacturers produced the identical drug, and Fitzgerald could not identify the specific maker. The court applied market-share liability so that each producer's share of the market supplied the factual-causation link.
Fusion Power employees stored unregistered firearms on company premises. Federal agents traced one weapon to a later crime. The court examined whether the company's possession was a factual cause of the subsequent misuse under the governing statute.
Freeman Engineering supplied a pneumatic tool whose guard failed. Operator Felicia Fuentes lost fingers when the tool kicked back. The jury had to decide whether the missing guard was the factual cause of the specific injury rather than the operator's own conduct.
Fidelity Trust fired Fatima Flores shortly after she filed an internal complaint. She sued under Title VII. The Supreme Court required her to prove that the complaint was the but-for factual cause of the termination rather than other performance issues.
Factual causation asks whether the harm would have occurred but for the defendant's conduct. Proximate causation then asks whether it is fair to hold the defendant legally responsible for that harm.
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When two or more defendants acted tortiously toward the plaintiff, the plaintiff suffered a single harm, and it is impossible to determine which defendant caused the harm, the burden shifts to each defendant to prove his conduct was not a factual cause.
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The rule bars homicide liability when death occurs more than a year and a day after the injury even if but-for causation is clear, functioning as a strict temporal limit rather than a test of factual causation itself.
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The plaintiff must show that the attorney's unreasonable conduct was significantly linked to the damages, meaning the client would have obtained a better result but for the negligence.
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…what he or she did as well.” In taking issue with this instruction, the defendants argue that the phrase “because of” requires but-for causation—a showing that they would not have acted but for the victim’s actual or perceived religious beliefs. The defendants have the better of the argument. In everyday usage, the phrase “because…