A proximate cause is an actual cause that is also legally sufficient to support liability. Although many actual causes can exist for an injury (e.g., a pregnancy that led to the defendant's birth), the law does not attach liability to all the actors responsible for those causes. The likelihood of calling something a proximate cause increases as the cause becomes more direct and more necessary for the injury to occur.
Proximate cause is often used as a standard in determining liability for torts and criminal offenses. Under tort law, the test for proximate cause is often foreseeability – if the harm that occurred was a foreseeable consequence of the action, then that action is a proximate cause of the harm. Another popular test for proximate cause is the substantial factor test – if the action was a substantial factor in the harm, then it will be deemed a proximate cause, while remote or trivial factors will only be actual causes rather than proximate causes.
For an example of proximate cause in jury instructions, consider Washington civil jury instructions WPI 15.01 Proximate Cause–Definition which states “The term “proximate cause” means a cause which in a direct sequence [unbroken by any superseding cause,] produces the [injury] [event] complained of and without which such [injury] [event] would not have happened. [There may be more than one proximate cause of an [injury] [event].]”
[Last updated in March of 2024 by the Wex Definitions Team]