Also known as: alternative liability doctrines · alternative liability · Summers v. Tice doctrine
Written by attorneys · grounded in primary & secondary sources — see below
A burden-shifting rule applicable when multiple defendants have each acted negligently toward the plaintiff. The plaintiff suffers a single indivisible harm caused by only one of them. Factual impossibility prevents the plaintiff from identifying which negligent act produced the injury. Each defendant must then prove that its own conduct was not the cause in fact of the harm.
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Easton stepped between two illegally parked buses operated by West Dispatch and Highland Transit. One bus lurched forward and crushed her foot. Witnesses gave conflicting accounts and the security footage was inconclusive, leaving it impossible to determine which bus made contact. Because both companies acted negligently and created the evidentiary gap, the court shifts the burden of disproving causation to each company.
Leo worked on one side of a partition while Gold Construct and Swift Concrete crews fired nail guns on the other side. A nail penetrated the partition and struck his leg. Both crews used identical nails and a coworker discarded the nail before examination, rendering it impossible to trace the source. The court therefore shifts the causation burden to each subcontractor.
The plaintiff must establish that each defendant acted negligently toward her, that she suffered a single indivisible harm, that the harm was caused by only one of the negligent acts, and that it is factually impossible for her to identify which defendant caused the injury. Once those elements are met, each defendant bears the burden to prove its conduct was not the cause in fact of the harm.
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No. The doctrine requires genuine factual impossibility of identification. Conflicting testimony or other evidence that could permit a jury to decide which defendant caused the harm means the burden does not shift and the plaintiff must prove causation by a preponderance of the evidence.
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The rule prevents an innocent plaintiff from going uncompensated when multiple negligent defendants have created an evidentiary deadlock that they are best positioned to resolve. It also deters negligent conduct by ensuring that wrongdoers cannot escape liability simply because their combined actions obscure the identity of the actual cause.
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Alternative liability applies to independent negligent acts that create unascertainable causation. Joint enterprise or concert of action requires proof that the defendants agreed to and jointly engaged in the wrongful activity so that each is liable for the acts of the others regardless of which one caused the harm.
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