'Res Ipsa Loquitur' is a Latin maxim used in the law of torts, which literally translates to "the thing speaks for itself." It is a rule of evidence that allows the plaintiff to establish a presumption of negligence on the part of the defendant without providing direct proof of negligence. The maxim applies when an accident occurs that is of a kind that does not ordinarily happen unless someone was negligent, and the instrumentality causing the injury was under the exclusive control of the defendant. The burden then shifts to the defendant to prove they were not negligent.