res ipsa loquitur

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Res Ipsa Loquitur

[Latin, The thing speaks for itself.] A rebuttable presumption or inference that the defendant was negligent, which arises upon proof that the instrumentality or condition causing the injury was in the defendant's exclusive control and that the accident was one that ordinarily does not occur in the absence of Negligence.

Res ipsa loquitur, or res ipsa, as it is commonly called, is really a rule of evidence, not a rule of Substantive Law.

Negligence is conduct that falls below the standard established by law for the protection of others against an unreasonable risk of harm. In order to prevail in a negligence action, a plaintiff must establish by a Preponderance of Evidence that the defendant's conduct was unreasonable in light of the particular situation and that such conduct caused the plaintiff's injury. The mere fact that an accident or an injury has occurred, with nothing more, is not evidence of negligence. There must be evidence that negligence caused the event. Such evidence can consist of direct testimony by eyewitnesses who observed the defendant's unreasonable conduct and its injurious result.

Negligence can also be established by Circumstantial Evidence when no direct evidence exists. Circumstantial evidence is evidence of one recognized fact or set of facts from which the fact to be determined can be reasonably inferred because it is the logical conclusion that can be drawn from all the known facts. For example, skid marks at the scene of an accident are circumstantial evidence that a car was driven at an excessive speed. The reasoning process must be based upon the facts offered as evidence, together with a sufficient background of human experience, to justify the conclusion. Evidence that merely suggests the possibility of negligence is insufficient, since negligence must appear more likely than not to have occurred. This inference must cover all the necessary elements of negligence: that the defendant owed the plaintiff a duty, which the defendant violated by failing to act according to the required standard of conduct, and that such negligent conduct injured the plaintiff.

Res ipsa loquitur is one form of circumstantial evidence that permits a reasonable person to surmise that the most Probable Cause of an accident was the defendant's negligence. This concept was first advanced in 1863 in a case in which a barrel of flour rolled out of a warehouse window and fell upon a passing pedestrian. Res ipsa loquitur was the reasonable conclusion because, under the circumstances, the defendant was probably culpable since no other explanation was likely. The concept was rapidly applied to cases involving injuries to passengers caused by carriers, such as railroads, which were required to prove they had not been negligent. Res ipsa loquitur, as it is in the early 2000s applied by nearly all of the 50 states, deals with the sufficiency of circumstantial evidence and, as in some states, affects the Burden of Proof in negligence cases.


Three basic requirements must be satisfied before a court can submit the question of negligence to the jury under res ipsa loquitur.

Inference of Negligence The plaintiff's injury must be of a type that does not ordinarily occur unless someone has been negligent. This requirement, which is the inference of negligence, allows res ipsa to be applied to a wide variety of situations, such as the falling of elevators, the presence of a dead mouse in a bottle of soda, or a streetcar careening through a restaurant. Although many of the cases involve freakish and improbable situations, ordinary events, such as where a passenger is injured when a vehicle stops abruptly, will also warrant the application of res ipsa. Commercial air travel became so safe in the late twentieth century that planes engaged in regularly scheduled commercial flights generally do not crash unless someone has been negligent. Vehicular accidents caused by a sudden loss of control, such as a car suddenly swerving off the road or a truck skidding on a slippery road and crossing into the wrong lane of traffic, justify the conclusion that such an event would not normally occur except for someone's negligence.

This inference of negligence does not mean that all other possible causes of the injurious event must be eliminated. A plaintiff using res ipsa to enable her case to go to the jury must prove that the defendant's negligence is the most probable cause of her injuries. The particular nature of the defendant's negligence need not be pinpointed. For instance, where a bottle of soda explodes in a supermarket immediately after its delivery by the bottler, the injured person does not have to prove that the bottler failed to notice a defect in the bottle or that the soda was over-carbonated. It is sufficient to establish that the explosion would not have occurred unless the bottler had been negligent.

Where the inference of negligence depends upon facts beyond the common knowledge of jurors, Expert Testimony is necessary to furnish this information. Such testimony is usually presented in cases of professional negligence, such as Medical Malpractice. An expert witness can testify directly in regard to the inferred fact itself, such as when the expert testifies that the plaintiff's injury would not have occurred if the doctor had not been negligent.

Exclusive Control by the Defendant The plaintiff's injury or damage must have been caused by an instrumentality or condition that was within the exclusive control of the defendant. Some courts interpret this requirement to mean that exclusive control or management must have existed at the time of the injury. This interpretation has led to harsh results. In one case, a customer sat down in a chair in a store while waiting for a salesperson. The chair collapsed and the customer was injured. The court denied recovery to the customer in her negligence action against the store because it found that the chair was not within the exclusive control of the store but rather was under the exclusive control of the customer at the time of injury.

This application of the rule has been regarded as inflexible by many courts, since it severely restricts the type of case to which res ipsa can be applied. In response, many states prescribe that the negligence must occur while the defendant has control over the instrumentality. In the example of the exploding soda bottle, the negligence of the bottler occurred somewhere in the bottling process. The fact that the bottle was sitting on a supermarket shelf and was no longer in the immediate possession of the bottler does not prevent the reasonable conclusion that the injury resulted from the negligence of the bottler. The injured plaintiff must first show that the bottle was not cracked by mishandling after it left the plant of the bottler. This does not mean, however, that the plaintiff must account for every minute of the existence of the bottle from the time it left the plant. If the plaintiff can substantiate the fact of careful handling in general and the absence of unusual incidents, such as the deliberate tampering of the bottled goods by an unknown person, such facts would permit reasonable persons to conclude that the injury was more likely than not to have been caused by the defendant's negligence while he had exclusive control of the bottle.

Since there must be exclusive control by the defendant, res ipsa cannot be used against multiple defendants in a negligence case where the plaintiff claims he has been injured by the negligence of another. For example, a pedestrian is injured when he is struck by a car that had just collided with another vehicle. The pedestrian institutes a negligence action against one driver and seeks to have res ipsa applied to his case. An inference of negligence does not arise from the mere fact of the collision, since neither driver is in exclusive control of the situation. If, however, one driver is cleared of fault by some specific evidence, the jury is justified in inferring that the injury was the result of the other driver's negligence.

The requirement of exclusive control by the defendant is not applied in cases involving Vicarious Liability or shared responsibility for the same instrumentality or condition. In one case, a person was injured when an elevator in which she was riding fell very rapidly. She brought a negligence action against both the owner of the building and the company that manufactured the elevator and had the maintenance service contract for the building. The plaintiff relied completely on res ipsa. The jury found for the plaintiff since a falling elevator is not the type of accident that usually occurs without negligence, so that the negligence of those in control can be inferred. The service contract between the elevator company and the building owner established the fact that they exerted joint control over the elevator. The requirement of exclusive control by a defendant of the instrumentality causing injury does not mean that only a single entity has control. Where two or more defendants are acting jointly, the doctrine of res ipsa can be applied to establish their negligence.

Some state courts have departed from the requirement of exclusive control and applied res ipsa loquitur against multiple defendants. In one case, while an anesthetized patient was undergoing an operation for appendicitis, he suffered a traumatic injury to his shoulder. Res ipsa was applied against all of the doctors and hospital employees connected with the operation, although not all of them were negligent. The court based its decision on the special responsibility for the plaintiff's safety undertaken by everyone concerned.

Freedom from Contributory Negligence The event in question must not have been attributable to any cause for which the plaintiff is responsible. The plaintiff must not have done anything that significantly contributed to the accident that caused the injury. In one case, a water skier was injured when the propeller of the boat that had been towing him struck his arm as the boat was attempting to pick him up. He sued the driver and the owner of the boat for negligence, which could be found if res ipsa was applied. The plaintiff attempted to dive underwater when he saw the boat approaching him, but he was unsuccessful in escaping injury. The defendants claimed that the attempted dive caused the accident and, therefore, res ipsa was inapplicable.

The trial court accepted this argument, which was later rejected by the appellate court. The appellate court decided that the question of whether the attempted dive caused the accident should have been presented to the jury under res ipsa. It stated that a plaintiff may rely upon res ipsa loquitur even though he has participated in the events leading to the accident if the evidence excludes his conduct as the responsible cause. In light of the skier's testimony that he was about to be struck by the boat, as well as the testimony of other eyewitnesses, the jury could logically conclude that the attempted dive was not a cause of the accident.

Accessibility of Evidence

In addition to the three basic requirements, a few states apply res ipsa in negligence cases where the evidence of the facts of the event is more accessible to the defendant than to the plaintiff. In one state, for example, a plaintiff was injured when the bleacher section in which she was sitting collapsed during a basketball game under the management and supervision of the defendant high school athletic association. She sued the association for negligence under the doctrine of res ipsa. The appellate court, reviewing a verdict for the plaintiff, affirmed it because "the underlying reason for the res ipsa rule is that the chief evidence of the true cause of the injury is practically accessible to the defendant but inaccessible to the injured person."

The Effect of Res Ipsa

Res ipsa loquitur is usually used when there is no direct evidence of the defendant's negligence. The facts presented to the court must meet the three basic requirements. Once the court decides that the facts of a particular case warrant the application of res ipsa, it instructs the jury on the basic principles, but it is the function of the jury to decide the credibility and weight of the inference to be drawn from the known facts. The jury can conclude that the defendant was negligent, but the jury is not compelled to do so. Everything depends upon the particular facts of each case. An inference of negligence might be so clear that no reasonable person could fail to accept it. If the defendant offers no explanation, the court can direct a verdict for the plaintiff if the inference is so strong that reasonable jurors could not reach any other conclusion. Where the jury considers the question of negligence, it can decide that the facts do not logically lead to an inference of the defendant's negligence, even if the defendant did not offer any evidence in her defense. If the defendant presents evidence that makes it unlikely that she has acted negligently, the plaintiff will lose his case unless he can rebut the evidence, since such evidence destroys the inference of negligence created by res ipsa.

A minority of courts hold that res ipsa creates a rebuttable presumption of negligence. Unless the defendant offers sufficient evidence to contradict it, the court must direct a verdict for the plaintiff. Some states have gone as far as to shift the burden of proof to the defendant, requiring her to introduce evidence of greater weight than that of the plaintiff.

Further readings

King, Michael G. 1999. "'Res' of the Story." Los Angeles Daily Journal (July 16).

Tanovich, David M. 2002. "Res Ipsa Loquitur and Racial Profiling." Criminal Law Quarterly 46 (October).


Evidence; Malpractice; Negligence; Probable Cause.

res ipsa loquitur

(rayz ip-sah loh-quit-her) n. Latin for "the thing speaks for itself," 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 without negligence the accident would not have happened. Examples: a load of bricks on the roof of a building being constructed by Highrise Construction Co. falls and injures Paul Pedestrian below, and Highrise is liable for Pedestrian's injury even though no one saw the load fall. While under anesthetic, Isabel Patient's nerve in her arm is damaged although it was not part of the surgical procedure, and she is unaware of which of a dozen medical people in the room caused the damage. Under res ipsa loquitur all those connected with the operation are liable for negligence. Lawyers often shorten the doctrine to "res ips," and find it a handy shorthand for a complex doctrine. (See: negligence)

res ipsa loquitur

noun automatic lack of due diliience, automatic negligence, automatic responsibility, breach of duty, certain dereliction, definite carelessness, doctrine of res ipsa loquitur, imprudence, irresponsibility, lack of attention, liability imposed for obvious responsibillty, liability for sole and exclusive control, obvious and cerrain negligence, the thing speaks for itself
Associated concepts: negligence

res ipsa loquitur

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