Also known as: unreasonably dangerous · unreasonable danger
Written by attorneys · grounded in primary & secondary sources — see below
Conduct that creates an unreasonable risk of physical harm to persons or property. The standard measures whether a reasonable person in the actor's position would recognize the danger as excessive and refrain from the conduct or take precautions to mitigate it.
Brook Media sold a lighting rig to Southern Studios for concert use. Ridge Stage installed the rig with minor adaptations for the venue grid. During the show the rig detached and struck concertgoer Trent. The mounting failure under normal conditions established that the rig reached the user in a condition creating an unreasonable risk of harm.
A resort owner hired an independent contractor to repair walkways open to guests. The contractor left an unmarked trench across a main path. Guest Umeko Uchida fell and broke her ankle. The resort's failure to supervise or warn created an unreasonably dangerous condition for which it remained responsible.
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A university therapist learned that patient Uri Underwood had named a specific student as a target. The therapist took no steps to warn the student or authorities. The student was later attacked. The therapist's inaction constituted unreasonably dangerous conduct that breached the duty to protect foreseeable victims.
Kay Denny bought a Ford Bronco II marketed for both on-road and off-road use. While driving on pavement the vehicle rolled over, causing severe injury. The design created an unreasonable risk of rollover during ordinary highway driving even though the vehicle performed as intended off-road.
Charterers purchased turbines that developed defects causing gradual deterioration. The turbines failed without injuring any person or other property. The court held that disappointment over product quality alone does not establish the unreasonable danger required for a tort claim.
A smoker sued cigarette manufacturers alleging that inadequate warnings rendered the product unreasonably dangerous. The manufacturers argued federal labeling statutes preempted the state tort claim. The court examined whether the conduct of selling cigarettes without stronger warnings met the unreasonable-danger standard under state law.
No. Under the Restatement rule a seller is subject to liability even when it has exercised all possible care in the preparation and sale of the product. The focus is on the condition of the product or conduct reaching the user rather than on the seller's fault.
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A substantial change in the product after sale can prevent liability if the change rather than the original defect caused the harm. Minor adaptations for installation that do not alter the fundamental risk do not break the chain.
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Yes. A possessor who holds land open to the public owes a duty to exercise reasonable care to protect entrants from unreasonably dangerous activities or conditions created by contractors or concessionaires on the premises.
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No. The standard also governs premises liability, professional duties, and other conduct that creates excessive risk to persons or property outside any sale transaction.
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…a duty of care to all persons who are foreseeably endangered by his conduct, with respect to all risks which make the conduct unreasonably dangerous." ( Rodriguez v. Bethlehem Steel Corp. (1974) 12 Cal.3d 382, 399 [115 Cal. Rptr. 765, 525 P.2d 669]; Dillon v. Legg, supra, 68 Cal.2d 728, 739; Weirum v. RKO General, Inc. (1975) 15…