Also known as: intervening acts · intervening cause · novus actus interveniens
Written by attorneys · grounded in primary & secondary sources — see below
An act by a third person occurring after the defendant's negligent conduct that contributes to the plaintiff's harm. The act does not relieve the defendant of liability when it is a normal or foreseeable consequence of the situation created by the negligence or when a reasonable person would not regard it as highly extraordinary.
Summit Gas delayed repairs on a known leak beneath a city block. During a permitted festival Chase connected a grill to a utility line without permission. The illegal connection ignited gas from the leak and injured Marion. The intervening connection did not supersede Summit Gas's liability because the leak remained a substantial factor and the hookup was a normal consequence of the hazard in a crowded area.
The City of Alexandria installed an unanchored sculpture in a high-traffic museum atrium knowing school groups visited weekly. Isabel allowed her students to push against the sculpture despite warning signs. The sculpture toppled and injured Hal. Isabel's negligent supervision did not supersede the city's liability because the museum should have realized students might crowd the unstable exhibit and the lapse was a normal consequence of the situation created.
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Two hunters fired negligently in the same direction. One pellet struck the plaintiff but it was impossible to determine which hunter fired the pellet. The hunters' concurrent negligence created the risk that made identification impossible. Neither hunter could escape liability by pointing to the other's shot.
A railroad employee dropped a package containing explosives on a platform. The resulting blast knocked over a scale that struck a passenger standing at the far end of the station. The passenger sued the railroad. The employee's negligent handling remained the legal cause because the explosion was within the risk created even though the precise chain of events was unusual.
A manufacturer sold flexible gas tubing containing a latent defect. The tubing ruptured in a home and caused a fire. Homeowners sued the manufacturer under strict products liability. The tubing's defect remained the legal cause of the harm despite any subsequent handling because the failure occurred during ordinary use.
An employee suffered a severe injury at work due to the employer's negligence. The employee's spouse sued for loss of consortium. The employer's negligence remained the legal cause of the spouse's harm because the injury directly impaired the marital relationship.
A third party's negligent intervening act does not supersede when the original actor should have realized the third person might act that way, when a reasonable person would not view the act as highly extraordinary, or when the act is a normal consequence of the situation created by the original negligence.
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An intervening act occurs after the defendant's conduct and contributes to the harm. It becomes superseding only when it is so extraordinary or independent that it breaks the chain of legal causation under the Restatement factors.
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No. Criminal conduct by a third party is more likely to be independent, yet it does not supersede if the original actor should have realized the likelihood that the situation would afford an opportunity for such conduct.
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Foreseeability determines whether the intervening act is a normal consequence of the risk created by the defendant. If the act is within the scope of the risk or not highly extraordinary, the original negligence remains a legal cause of the harm.
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…knocks down with his car a pedestrian and a third person then ran over the prostrate person. That involves the question of intervening cause which we do not have here. Moreover it is out of harmony with the current rule on that subject and was properly questioned in Hill v. Peres , 136 Cal.App. 132 [28 P.2d 946] (hearing in…