Also known as: superseding cause · superseding causes · superseding cause doctrine
Written by attorneys · grounded in primary & secondary sources — see below
An intervening act or force of a third person that prevents the original actor from remaining liable for harm to another even though the antecedent negligence was a substantial factor in bringing the harm about. The doctrine operates by cutting off the chain of legal causation when the intervening event is independent, unforeseeable in type, and extraordinary under the circumstances.
Select any source to read its text and confirm it supports the definition.
Lena authorized a pressure increase in a transmission line. A construction firm had previously weakened a distant pipe segment through unauthorized digging. The weakened segment ruptured after the pressure rose. The digging is treated as a superseding cause that cuts off Lena's liability for the resulting explosion and injuries.
Luis waved an unloaded pistol at suspected shoplifters inside a convenience store. One teenager panicked and sprinted into traffic. A passing car struck and killed the teenager. The driver's conduct is not a superseding cause because the flight into the street was a normal consequence of the brandishing.
Luis carried ten passengers on a vessel limited to six during choppy seas. A large wave struck and the boat capsized. Passenger Carla drowned. The wave is not a superseding cause because it was a foreseeable maritime hazard that the overloading increased.
Lena ordered all emergency exits at an outdoor music festival chained shut. A small stage fire broke out. Panicked attendees could not exit and one fan was trampled to death. The fire is not a superseding cause because the chained exits created the foreseeable risk of a deadly crush.
Lopez instructed staff to delay approval of expensive cancer treatments. Rivera learned his therapy would be postponed and chose not to seek alternatives. Rivera died several weeks later. Rivera's decision is not a superseding cause because it was a normal response to the imposed delay.
Daisy removed Joe's specialized mobility scooter without consent to move another patient. Joe needed the bathroom and attempted to walk using only the bed rail. Joe fell and fractured his hip. Joe's choice to walk is not a superseding cause because it was a normal effort to avert the harm created by the scooter's absence.
An intervening act qualifies as a superseding cause only when it is independent in origin, unforeseeable in type, and extraordinary rather than a normal consequence of the original negligence. The Restatement factors in section 442 guide the inquiry by examining whether the harm differs in kind, appears extraordinary after the fact, or stems from a third person's wrongful act. If the intervening force remains within the risk created by the original conduct, it does not supersede.
Supporting sources
A victim's conduct can constitute a superseding cause when it is an independent, unforeseeable, and extraordinary response rather than a normal reaction to the danger created by the defendant. Normal efforts to avoid threatened harm or reactions driven by fear do not break the chain. The doctrine therefore preserves liability when the victim's response stays within the foreseeable risks of the original negligence.
Supporting sources
The doctrine remains applicable in admiralty and operates to cut off liability entirely when an independent, unforeseeable later cause produces the injury. It is consistent with comparative fault because it identifies situations in which the original defendant's negligence is no longer a legal cause. Courts therefore apply it before apportioning damages among remaining tortfeasors.
Supporting sources
An intervening act is not a superseding cause when the resulting harm is the same general type of risk the defendant's conduct created and is not too remote or freakish. Unauthorized digging that weakens a pipe does not supersede liability for over-pressurizing the line because the explosion remains within the foreseeable risk of rupture. The jury must still decide whether the additional causal requirement for the result crime is satisfied.
Supporting sources