Sine Qua Non
Literal meaning: “Without which not”
What does the Latin term "Sine Qua Non" mean in law?
Sine qua non describes an indispensable condition or element without which something cannot exist or occur. In tort law, it is synonymous with the 'but-for' test of actual causation: the defendant's conduct is a cause of the plaintiff's injury if the injury would not have occurred but for that conduct. This test establishes factual causation as distinct from proximate or legal causation. Beyond torts, the phrase is used broadly in legal analysis to identify any essential prerequisite to a legal outcome, such as an element of a cause of action that must be satisfied for a claim to succeed.
Source: Torts · Legal Latin
Legal Definition
Sine qua non describes an indispensable condition or element without which something cannot exist or occur. In tort law, it is synonymous with the 'but-for' test of actual causation: the defendant's conduct is a cause of the plaintiff's injury if the injury would not have occurred but for that conduct. This test establishes factual causation as distinct from proximate or legal causation. Beyond torts, the phrase is used broadly in legal analysis to identify any essential prerequisite to a legal outcome, such as an element of a cause of action that must be satisfied for a claim to succeed.
How It's Used
Courts and legal scholars use sine qua non interchangeably with 'but-for causation' when analyzing whether a defendant's act was a necessary antecedent to harm. The term also appears in contract and constitutional analysis to identify conditions without which an agreement or right cannot function.
Example Sentences
The plaintiff's expert testified that the defendant's negligence was the sine qua non of the bridge collapse, as the structure would not have failed absent the design error.
Freedom of the press is the sine qua non of a functioning democracy, the court declared in striking down the prior restraint.
The appellate court held that the but-for test, or sine qua non standard, was the appropriate causation framework for the employment discrimination claim.