Also known as: supervening causes · superseding cause
Written by attorneys · grounded in primary & secondary sources — see below
An act of a third person or other force that intervenes after an actor's negligent conduct and prevents that conduct from remaining a legal cause of harm to another. The intervention relieves the original actor of liability when it qualifies as superseding under the governing tests for extraordinary or abnormal forces.
Summit Gas delayed repairs on a known leak beneath a residential block. During a city festival Chase illegally connected a grill to a utility line. The connection ignited gas from the unrepaired line and injured Marion. The illegal hookup operated as an independent force that directly produced the explosion.
The City of Alexandria installed an unanchored sculpture in a high-traffic museum atrium knowing school groups visited weekly. Teacher Isabel allowed students to push against the sculpture. The sculpture toppled and injured visitor Hal. Isabel's lapse was a normal response to the situation the museum created.
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Birch Media sold unsecured glass bottles in an upper balcony despite repeated warnings about intoxicated patrons leaning over railings. Banned patron Henry entered through an unrepaired door and dropped a bottle during an unforecast storm. The bottle struck Norman below. The storm's operation and Henry's conduct raised questions whether either force qualified as extraordinary.
Summit Gas left a known gas leak accessible near utility lines during a permitted festival. Chase's illegal grill connection increased the risk the leak created. The explosion injured Marion. The connection did not relieve Summit Gas because the leak increased the foreseeable risk of harm through that very intervention.
A museum placed an unstable sculpture near school groups despite knowing the risk of physical contact. Teacher Isabel panicked when students began pushing and failed to stop them. The sculpture fell on Hal. Isabel's panicked inaction was a normal response to the fear the museum's placement created.
Birch Media failed to install barriers near the stage despite known risks of surging patrons. During a storm Henry surged forward to escape the weather and dropped a bottle. The bottle injured Norman. Henry's surge was a normal effort to avoid the harm the missing barriers threatened.
An intervening act qualifies as a supervening cause when it prevents the actor's antecedent negligence from remaining a substantial factor in bringing about the harm. The Restatement tests focus on whether the intervention was extraordinary, produced a different kind of harm, or operated outside the risk the negligence created.
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No. A third party's criminal or negligent act does not automatically supersede when the original negligence created or increased the foreseeable risk of that very intervention. Liability remains if the act was a normal consequence of the situation the actor's conduct produced.
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Courts weigh whether the force brought about harm different in kind from that threatened by the negligence, whether its operation appeared extraordinary after the fact, and whether it was a normal response to the risk the actor created. The factors in § 442 guide the determination.
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A force of nature is a supervening cause only when its operation is extraordinary or produces harm different in kind from the risk the negligence created. An ordinary storm that merely triggers a foreseeable risk does not relieve the actor of liability.
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…of its approach limit a manufacturer’s liability if the subsequent alteration or modification was the sole proximate cause or a superseding cause leading to the plaintiffs injury. See Santiago v. Package Machinery Co. , supra, 123 Ill. App. 2d 312 (considering whether sole proximate cause of the injury was the conduct of another”…