Res ipsa loquitur is a Latin term meaning "the thing speaks for itself". It is a doctrine of law that one is presumed to be negligent if he/she/it had exclusive control of whatever caused the injury even though there is no specific evidence of an act of negligence, and the accident would not have happened without negligence. The traditional elements needed to prove negligence through the doctrine of res ipsa loquitur include:
- 1. The harm would not ordinarily have occurred without someone's negligence
- 2. The instrumentality of the harm was under the exclusive control of the defendant at the time of the likely negligent act
- 3. The plaintiff did not contribute to the harm by his own negligence.
There has been some change in the modern application of the above elements. The "exclusive control" element has been softened in modern cases to a less strict standard, where the plaintiff must prove that other responsible causes, including the conduct of the plaintiff and third persons, are sufficiently eliminated by the evidence. The last element has also softened to a more comparative standard, so that if plaintiff was only 5% negligent in contributing to the accident, the minimal contributory negligence of the plaintiff won't bar a recovery.