Also known as:alternative liability theories · alternative liability
Written by attorneys · grounded in primary & secondary sources — see below
A tort doctrine shifting the burden of proving factual causation when multiple defendants each acted negligently toward the plaintiff, the plaintiff suffered a single indivisible harm from only one of those acts, and the plaintiff cannot identify which defendant caused the harm. Each negligent defendant must then prove that its conduct was not the cause in fact of the injury. If a defendant cannot carry that burden, it remains liable, typically jointly and severally with the others.
Sources & Authorities
How it applies
Common Examples
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Bus Drivers and Pedestrian Injury
Adrian Aguilar stepped between two buses parked illegally near a crosswalk at a busy terminal. One bus lurched forward and crushed his foot. Witnesses gave conflicting accounts and security footage was inconclusive, making it impossible to determine whether the Azure Solutions or Artemis Logistics bus made contact. Both companies had ignored warnings about parking too close to the walkway. The court shifted the burden of proving causation to both companies because each had been negligent and only one caused the harm.
Nail Gun Injury at Construction Site
Alan Ackerman worked on one side of a partition while Gold Construct and Swift Concrete crews fired nail guns on the other side despite warnings to use barriers. A nail struck Ackerman in the leg. The nail was discarded before testing and both crews used identical nails, so no one could determine which crew fired the injurious nail. The court shifted the causation burden to both subcontractors under the doctrine.
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Cases
Course Outlines
Common questions
Frequently Asked
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When does the alternative liability doctrine shift the burden of proving causation?+
The doctrine applies when two or more defendants each acted negligently toward the plaintiff, the plaintiff suffered a single indivisible harm caused by only one of them, and it is factually impossible for the plaintiff to prove which defendant caused the harm. The burden then shifts to each negligent defendant to prove its conduct was not the cause in fact of the injury.
Supporting sources
Does the doctrine require the plaintiff to prove which defendant caused the harm?+
No. Once the plaintiff shows that all defendants were negligent, that one caused the single harm, and that identification is impossible, the burden shifts to the defendants. The plaintiff need not identify the specific tortfeasor.
Supporting sources
What happens if a defendant proves its act did not cause the harm?+
That defendant escapes liability. The doctrine allows any defendant that affirmatively shows its conduct was not a cause in fact of the injury to avoid joint and several liability.
Supporting sources
Can the doctrine apply when defendants used different but similar substances?+
Yes, provided the other elements are met. Courts have applied the doctrine to cases involving different pesticides or chemicals when expert evidence shows it is impossible to attribute the harm to one source over the other.
Supporting sources
26 Cal. 3d 588 (1980)Torts
…may shift to the defendants to show that they were not responsible for the harm. This principle is sometimes referred to as the "alternative liability" theory. The celebrated case of Summers v. Tice , supra , 33 Cal.2d 80, a unanimous opinion of this court, best exemplifies the rule. In Summers , the plaintiff was injured when two…
TortsNegligence · Actual causationNEXTGENFoundational