Also known as: efficient causes · proximate cause
Written by attorneys · grounded in primary & secondary sources — see below
A cause that produces a result in a natural and continuous sequence unbroken by any efficient intervening cause. Liability attaches only when this cause is both the factual and legal origin of the harm.
Select any source to read its text and confirm it supports the definition.
Erika Echevarria left her loaded handgun on a low table where her twelve-year-old son could reach it. The boy took the gun to school and accidentally shot a classmate. Erika's failure to secure the weapon operated as the efficient cause of the injury because her negligent supervision directly enabled the shooting without any superseding event.
Edgar Evers received Phenergan by the IV-push method after his physician reviewed the existing label. The drug caused gangrene that required amputation. The manufacturer's omission of an adequate warning on that method functioned as the efficient cause because the injury would not have occurred if the label had contained the missing risk information.
Emmett Egan's derailed train released toxic chemicals near People Express Airlines' terminal. The spill forced a three-day shutdown that produced substantial lost profits. The derailment and resulting evacuation served as the efficient cause of the economic harm because the airline's losses flowed directly from the spill without independent intervening factors.
Elena Estrada carried a package containing fireworks onto a crowded train platform. Railroad employees negligently dislodged the package, causing an explosion that knocked over scales at the far end of the platform and injured Emma Erickson. The employees' mishandling of the package constituted the efficient cause of Erickson's injuries because the chain of events remained unbroken from the initial negligence.
Elliot Edmonds sold refurbished printer cartridges bearing counterfeit Lexmark labels. Static Control Components lost sales when customers bought the mislabeled products. Edmonds's false labeling operated as the efficient cause of the lost sales because the deception directly diverted customers who would otherwise have purchased from Static Control.
Eclipse Manufacturing failed to pay federal taxes, resulting in a lien on its equipment. Darue Engineering purchased the equipment at a tax sale without notice of the lien. The IRS's lien constituted the efficient cause of the title dispute because the government's interest arose directly from the unpaid taxes and remained attached through the sale.
Efficient cause requires both factual causation and legal proximity. Cause in fact asks whether the harm would have occurred but for the defendant's conduct. Efficient cause further demands that the conduct be a substantial factor in a continuous sequence that produces the result without superseding events.
An intervening act breaks the chain only when it is unforeseeable and independent of the original conduct. If the later event is a normal response to the initial negligence or is itself caused by that negligence, the original conduct remains the efficient cause of the harm.
…corporation, in the federal court for the southern district of that State. The issues were whether negligence of defendant was a proximate cause of his injuries and whether negligence of plaintiff contributed. He claimed that, by hauling the car with the open door, defendant violated a duty to him. The defendant insisted that it…