What is Res Ipsa Loquitur?

Alexis W.

Res ipsa loquitur is a Latin phrase meaning "the thing speaks for itself." It is a method of proving that a tort occurred in certain types of civil trials. In other words, it permits a plaintiff in certain tort cases to simply invoke res ipsa loquitur to prove the negligence element of a tort cause of action.

Res ipsa loquitur might be invoked when an obviously-dangerous workplace environment led to an accident.
Res ipsa loquitur might be invoked when an obviously-dangerous workplace environment led to an accident.

Typically, when a plaintiff sues a defendant for a tort, the plaintiff must prove several elements of a case. First, the plaintiff must prove that the defendant intentionally or negligently caused the injuries to occur. Second, the plaintiff must prove that he actually suffered damage as a result of the defendant's actions.

When res ipsa loquitur is invoked, the doctrine permits the plaintiff to win his case without explicitly proving negligence. It, essentially, is a doctrine that says that the action that caused the injury was so obviously negligent that the action speaks for itself and no additional proof is required. If this doctrine applies and is accepted by the court, the plaintiff only has to prove that he incurred damages as a result of the defendant's actions in order to win the case.

Res ipsa loquitur is an acceptable form of proof in the United States, Hong Kong and Scotland. It is known by different names in different countries. Canada has essentially overruled the doctrine of res ipsa loquitor. England uses the doctrine to suggest a strong presumption in favor of assuming negligence, but it cannot be conclusive evidence.

This doctrine is appropriate when an injury-causing action meets four separate criteria. If these four criteria apply, it can be invoked to demonstrate that the action was negligent. This means the plaintiff will be able to win her case without explicitly proving negligence.

The four criteria for res ipsa loquitur to apply are that: the accident would not occur unless negligence was involved; in the particular situation it did not occur without negligence involved; the action or event was caused by an instrument that was under the defendant's exclusive control; and the accident or injury was not in any way caused or contributed to by the plaintiff in the case. This means that if the plaintiff was contributorily negligent, or also behaved in some way that led to the accident, the plaintiff cannot invoke res ipsa loquitur. It also means that whatever harmed the plaintiff must have been exclusively managed or controlled by the defendant and no other individual.

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Discussion Comments


A surgical nurse told me about a medical negligence case that was able to use the res ipsa loquitur principle. A doctor performed a hysterectomy on a woman, and a major nerve was injured and caused paralysis of her left arm.

To show medical negligence and use res ipsa loquitur, she needed expert medical testimony to show that her injury was likely caused by negligence. She would need to show that the surgeon was under control of the surgery. And then she would need to show that she had no part in the injury - easy to show if the person is unconscious.

Unless the medical case is very complicated, using res ipsa loquitur is pretty straight forward. The important thing is to get a good medical expert to testify for you.


I was involved in an injury traffic accident a few years ago. I was injured and it was clearly the fault of the other driver.

I hired a lawyer and after about two years, the case was settled and I was paid a sum by the defendant's insurance company.

If it hadn't settled and we went to civil trial, I think that it would have followed the res-ipsa-loquitur (the claim speaks for itself) doctrine.

In my case, the defendant was negligent and I had no part in the negligence. The accident and injury was caused by a car, which the defendant had control of. My lawyer wouldn't have to have proven negligence, since the negligence by the defendant was so obvious.

Court costs are so high, I'm sure I came out ahead by settling the case.

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