Also known as:sine qua non · sine qua non test · sine qua non causation · but-for rule · but for test · but-for causation
Written by attorneys · grounded in primary & secondary sources — see below
A test for factual causation under which conduct qualifies as a cause of a result if the result would not have occurred in the absence of that conduct. The test isolates the necessary antecedent condition without which the harm would not have taken place.
Sources & Authorities
How it applies
Common Examples
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Nurse Overdose and Delayed Death
Dana, an overworked nurse, mistakenly administered a massive overdose of a monitoring drug to Mr. Lopez. The overdose severely damaged his organs and left him in fragile condition. Fifteen months later Mr. Lopez died during a final episode of heart failure. In a jurisdiction applying traditional common law homicide rules, the prosecutor cannot charge Dana with criminal homicide because the death occurred outside the one-year-and-a-day window even though the overdose was a but-for cause of the fatal heart failure.
Unlawful Entry and Evidence Discovery
Officers entered Hudson's home without complying with the knock-and-announce requirement and seized incriminating evidence inside. The entry itself was a necessary condition of their presence in the home. Their discovery of the evidence was a readily foreseeable consequence of that presence. The unlawful entry therefore satisfies the but-for test for causation of the seizure.
Select any source to read its text and confirm it supports the definition.
Common Law
Casebooks
Hornbooks
Hudson v. Michigan547 U.S. 586 (2006)
Telephone Listings and Copyright Claim
Rural Telephone Service compiled a directory of subscriber names and numbers. Feist Publications copied those listings into its own directory without independent effort. But for Rural's original compilation, the listings would not have existed for Feist to copy. The but-for relationship establishes factual causation between Rural's labor and Feist's copying.
Feist Publications, Inc. v. Rural Telephone Service Co.499 U.S. 340, 349-350 (1991)
Crime Profits and Speech Restriction
Simon & Schuster contracted to publish a book by a convicted criminal and paid the author for his story. The New York Crime Victims Board sought to divert those payments to victims under a state law. But for the book's publication and the resulting payments, the board would have had no funds to seize. The but-for link connects the publisher's conduct to the board's enforcement action.
Simon & Schuster, Inc. v. Members of the New York State Crime Victims Board502 U.S. 105 (1991)
Secondary Actors and Securities Fraud
Stoneridge Investment Partners purchased securities whose price had been inflated by a scheme involving Scientific Atlanta's undisclosed transactions. But for Scientific Atlanta's participation in the transactions that concealed the scheme, the inflated price and resulting investor losses would not have occurred. The but-for relationship supplies factual causation between the secondary actor's conduct and the investors' harm.
Stoneridge Investment Partners, LLC v. Scientific Atlanta, Inc.552 U.S. 148, 158 (2008)
Physician Disclosure and Patient Consent
Dr. Spence performed spinal surgery on Canterbury without disclosing the risk of paralysis. Canterbury suffered paralysis after the procedure. But for the nondisclosure, Canterbury would have refused the surgery and avoided the paralysis. The but-for relationship establishes factual causation between the physician's failure to disclose and the patient's injury.
Canterbury v. Spence150 U.S.App.D.C. 263, 464 F.2d 772 (D.C.Cir.1972), cert. den. 409 U.S. 1064
Common questions
Frequently Asked
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What does the sine qua non rule require to establish factual causation?+
The rule requires proof that the result would not have occurred in the absence of the defendant's conduct. This but-for inquiry isolates the necessary antecedent condition without which the harm would not have taken place.
Supporting sources
Does satisfaction of the sine qua non rule guarantee liability in homicide cases?+
No. Even when but-for causation is clearly satisfied, common law homicide liability is barred if the victim dies more than one year and one day after the injury. The temporal limitation operates independently of the but-for test.
Supporting sources
How does the sine qua non rule differ from proximate cause?+
The sine qua non rule addresses only cause in fact by asking whether the harm would have occurred without the conduct. Proximate or legal cause further limits liability by requiring that the harm be a foreseeable result of the conduct even when but-for causation is established.
Supporting sources
Can multiple acts each satisfy the sine qua non rule for the same result?+
Yes. Several independent acts can each qualify as a but-for cause when the result would not have occurred without any one of them. The presence of additional causes does not eliminate the but-for status of any single antecedent condition.
Supporting sources
530 U.S. 466 (2000)Evidence
…that this hate crime law defines a particular kind of prohibited intent , and a particular intent is more often than not the sine qua non of a violation of a criminal law. When the principal dissent at long last confronts the actual statute at issue in this case in the final few pages of its opinion, it offers in response…