Res Ipsa Loquitur

The Latin term res ipsa loquitur translates to “the thing speaks for itself,” and is used in the U.S. legal system to refer to a doctrine of law in which an individual is assumed to have been negligent because he had exclusive control over the incident that caused the injury or damages. This assumption may be made even without specific evidence of negligence, as the accident, injury, or damages would not have occurred in the absence of negligence. To explore this concept, consider the following res ipsa loquitur definition.

Definition of Res Ipsa Loquitur


rayz ip-sah loh-quit-her


  1. A rule of law in which negligence is presumed when the object or situation which caused injury or damage was under his or her control, and the damage could not have happened had negligence not occurred.


1650-1660       Latin

Use of Res Ipsa Loquitur

The doctrine of res ipsa loquitur may be used as a “rebuttal presumption” when a defendant accused of negligently causing injury or damages asserts there is no proof of his involvement or negligence. When an individual files a civil lawsuit seeking payment for damages caused by the defendant’s negligence, he must prove to the judge or jury that:

  1. The defendant had a duty to perform in a certain manner
  2. The defendant breached that duty or performed negligently
  3. The defendant’s breach of duty caused the plaintiff’s damages

In the event the defendant denies having acted negligently, the plaintiff may, according to res ipsa loquitur, rebut the defendant’s claim, pointing out that the incident could not have occurred unless there was some negligence.

For example:

Eleanor walks her dog, Sadie, several blocks to the dog park every afternoon around 4 p.m. On Tuesday, as Eleanor and Sadie were passing a neighbor’s house, his husky charged out from the side of the property and attacked Sadie. Another neighbor helped get the husky off Sadie, though she was seriously injured, and Eleanor had been bitten twice.

When Eleanor presented her veterinary and medical bills to the dog’s owner, he refused to pay, saying he doesn’t know whether it was really his dog that attacked the pair, and that his dog is always locked in the back yard. When Eleanor takes her claim to small claims court, suing the neighbor for the $4,018 in medical and vet bills, the neighbor states that he is diligent in keeping his dog in the back yard, and so someone must have let it out, which is not his fault.

The judge rules in Eleanor’s favor, and awards her the full amount of damages, explaining to the defendant that, even though there is no proof that he personally let the dog out, he is always responsible for keeping the dog safely confined. According to the doctrine of res ipsa loquitur, the incident could not have happened without negligence, and so the responsibility belongs to the defendant.

Elements of Res Ipsa Loquitur

Using the principle of res ipsa loquitur in a civil lawsuit requires the plaintiff to prove several specific elements existed at the time of the incident. These include:

  1. The injury or damages sustained could not, under ordinary circumstances, occur without negligence on the part of the defendant.
  2. The object or occurrence that caused the injury or damages was within the defendant’s exclusive control.
  3. The incident did not occur due to any voluntary action of, or participation by, the plaintiff.
  4. The defendant’s explanation of non-negligence does not adequately explain the plaintiff’s injury or damages.

Meeting the First Element of Res Ipsa Loquitur

Certain circumstances exist which leave little to no doubt as to the defendant’s negligence or culpability for the harm suffered by the plaintiff. This may be proven in one of three ways:

  1. The injury or damage itself proves blatant or obvious negligence, such as a surgical team leaving instruments inside a patient’s body.
  2. Society’s general experience and observation are adequate to support the claim of negligence, such as a surgeon performing a hysterectomy on a patient who only consented to having her tubes tied.
  3. Expert testimony strongly suggests that the injury could only have been caused by negligence, such as an experienced surgeon testifying that, having performed more than 800 appendectomies, he has never damaged a patient’s liver, which is not located near the appendix, nor does he know of any of his colleagues who have caused injury to a patient’s liver during an appendectomy.

Meeting the Second Element of Res Ipsa Loquitur

The requirement that the circumstance, event, or object that caused the plaintiff’s injury or damages be under the defendant’s exclusive control has been modified over the years, as proving exclusive control can be quite difficult. The less rigid requirement of this element of res ipsa loquitur requires that evidence essentially eliminates, to a great degree, other possible causes or other responsible parties, for the injury or damages.

For example:

Amy hired a landscape company to install a sprinkler system in her yard, as well as a faucet on the side wall of the home. Several days after the job was done, Amy used the faucet for the first time, when she attached a drip hose, turned the faucet on low as instructed by the landscaper, and left the drip line to water her trees for about two hours while she went shopping. When Amy returned home that afternoon, she found her entire back and side yards flooded, with water streaming from the faucet where it connected to the house.

The landscaping company claims the faucet worked properly when it was installed, and that Amy had no proof that they did anything wrong, or that it was their fault the faucet leaked. In spite of the landscapers’ denial of responsibility, there is little reason to believe someone else could have been responsible. Res ipsa loquitur holds that it is more likely than not that the faucet had been installed incorrectly, and that the landscaping company should be responsible to pay for Amy’s damages.

Meeting the Third Element of Res Ipsa Loquitur

The third element of res ipsa loquitur involves showing that the plaintiff did nothing to contribute to his own injury or damages.

For example:

Roland’s car spun out of control after he hit a rough area where road construction was under way, finally stopping when it slammed into a utility pole at the side of the road. Roland, who was seriously injured, claims there should have been a sign warning him of the extreme rough condition of that part of the road, even though the construction zone had been clearly marked a half mile back, and the proper safety signs, cones, and other equipment were being used.

At trial, testimony of three witnesses and a police officer show that Roland had been traveling in excess of 60 mph through the construction zone, where a temporary speed limit of 30 mph was clearly posted. Roland’s own negligence contributed to the accident and his injuries, therefore he cannot hold the construction company responsible for damages.

Meeting the Fourth Element of Res Ipsa Loquitur

The fourth element of res ipsa loquitur recognizes that a defendant can overcome a res ipsa loquitur claim by presenting evidence that a non-negligent occurrence fully accounts for the plaintiff’s injury or damages. In the event the defendant’s explanation in such a situation does not add up or fully explain the plaintiff’s damages, this defense may fail.

Res Ipsa Loquitur vs. Prima Facie

The term res ipsa loquitur is frequently confused with the term prima facie, though there is a significant difference between the two as used in the legal system. Res ipsa loquitur refers to a situation in which the facts of a case make it self-evident that the defendant’s negligence caused the plaintiff’s injury or damages. Prima facie, which means “at first glance,” refers to the fact that enough evidence exists, if taken at face value, to file charges or pursue a legal action.

Res Ipsa Loquitur in Practice

The principle of res ipsa loquitur can be applied in a variety of situations in which an individual or entity is accused of negligently causing someone’s injury or damages.

The Stray Barrel of Flour

In 1863, as a man named Byrne was strolling past Broadle’s flour shop, a barrel of flour rolled out of a window overhead and landed on him, causing significant injury. Byrne filed a civil lawsuit against the flour shop, claiming it had been negligent in failing to keep the barrel contained. At trial, an eyewitness testified that he had seen the barrel fall from Broadle’s window and strike Byrne, though he did not see the cause of the barrel’s fall.

Broadle, owner of the flour shop, asked the court to dismiss Byrne’s case, as he had no evidence of negligence. Although there was no evidence that Broadle or any of his employees directly took any action that resulted in the plaintiff’s injuries, the court eventually held that Broadle had a duty of care to control the contents of the warehouse. In addition, Broadle had exclusive control over the barrel, and he should have installed some safety measures to prevent just such an occurrence.

Related Legal Terms and Issues

  • Civil Lawsuit – A lawsuit brought about in court when one person claims to have suffered a loss due to the actions of another person.
  • Damages – A monetary award in compensation for a financial loss, loss of or damage to personal or real property, or an injury.
  • Defendant – A party against whom a lawsuit has been filed in civil court, or who has been accused of, or charged with, a crime or offense.
  • Negligence – Failure to exercise a degree of care that would be taken by another reasonable person in the same circumstances.
  • Plaintiff – A person who brings a legal action against another person or entity, such as in a civil lawsuit, or criminal proceedings.

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