Res ipsa loquitur, a Latin phrase meaning 'the thing speaks for itself,' is a doctrine in tort law that allows a plaintiff to establish a rebuttable presumption of negligence through circumstantial evidence. To invoke the doctrine, a plaintiff must typically demonstrate three elements: the event was of a kind that does not ordinarily occur in the absence of negligence, the instrument of harm was under the exclusive control of the defendant, and the plaintiff did not contribute to the injury. In a classic example, a barrel falling from a warehouse window and striking a pedestrian would allow for a res ipsa loquitur claim, as barrels do not typically fall from windows unless someone was negligent in securing them. Critics of the doctrine argue that it can unfairly shift the burden of proof to defendants who may have been diligent but are unable to provide evidence of their own non-negligence years after an event. They suggest that res ipsa loquitur essentially allows for a finding of 'negligence in the air,' where a jury is permitted to speculate based on the mere fact of an accident. Defenders, however, argue that the doctrine is essential for justice in cases where the evidence of what actually happened is uniquely within the knowledge of the defendant. Without it, they claim, defendants would have an incentive to remain silent or fail to keep records, effectively immunizing themselves from liability for obvious failures.