Res Ipsa Loquitur

Res Ipsa Loquitur is a legal doctrine that allows an inference of negligence to be made when the facts of a case suggest that an accident could not have occurred without someone's negligence. It shifts the burden of proof to the defendant to show that they were not negligent.

The maxim originated in English tort law, stemming from the medieval legal principle that evidence should be sufficient to support a claim of liability. It was formally articulated in the 1868 case of Byrne v. Boadle, where a barrel falling from a warehouse proved negligence even without direct evidence.

In modern law, Res Ipsa Loquitur is frequently applied in cases involving accidents that are uncommon and typically indicative of negligence, such as surgical errors or falling objects from buildings. Courts allow juries to infer negligence based on the circumstances when direct evidence of the defendant's actions is not available.

• A patient suffers an injury during surgery, and no explanation is provided for how the injury occurred, suggesting that the surgical team was negligent.
• A car accident occurs where a vehicle suddenly swerves and crashes without any direct evidence of an external cause, leading to an inference that a malfunctioning part or driver error caused the accident.

• Byrne v. Boadle
• Larson v. St. Louis University