res ipsa loquitur

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Res ipsa loquitur is Latin for "the thing speaks for itself."  


Res ipsa loquitur is a principle in tort law that allows plaintiffs to meet their burden of proof with what is, in effect, circumstantial evidence. The plaintiff can create a rebuttable presumption of negligence by proving that the harm would not ordinarily have occurred without the negligence of the defendant, that the object that caused the harm was under the defendant’s control, and that there are no other plausible explanations.  

Prima Facie Case Test:

To prove res ipsa loquitur negligence, the plaintiff must prove 3 things:

  1. The incident was of a type that does not generally happen without negligence
  2. It was caused by an instrumentality solely in defendant’s control
  3. The plaintiff did not contribute to the cause 

Limitations on Res Ipsa Loquitur 

An injury which would not occur without some fault of the plaintiff (i.e. certain types of slip-and-fall accidents) would necessarily fail the prima facie test, specifically the third element. 

Further Reading

For more on res ipsa loquitur, see this Yale Law Review note and this St. John's Law Review note

For an example of a court applying res ipsa loquitur, see Byrne v Boadle.

[Last updated in May of 2024 by the Wex Definitions Team]