What Is Res Ipsa Loquitur in a Personal Injury Case?
Res Ipsa Loquitur is a Latin term meaning “the thing speaks for itself.” In personal injury law, it is a doctrine that allows the accident itself to be evidence of negligence, even when the exact act of negligence is unknown.
This tool bypasses the need to identify the specific negligent act and lets the jury infer that the defendant was likely at fault.
How Res Ipsa Loquitur Works
When Res Ipsa Loquitur applies, a court can:
Deny a motion for summary judgment
Submit the case to the jury on breach of duty, allowing them to infer negligence
It is typically used in cases where accidents happen under circumstances that would not ordinarily occur without negligence, such as:
Objects falling
Explosions
Elements of Res Ipsa Loquitur
Modern courts generally require three elements:
The injury was probably the result of negligence
The accident is the type that ordinarily would not occur without someone being negligent.
The defendant was at least probably negligent
More likely than not, the defendant’s actions caused the harm.
Absence of explanation from the defendant
The defendant cannot offer an alternative explanation for what happened.
Older test: Some courts require exclusive control of the instrumentality causing the harm to satisfy element 2.
Res Ipsa Loquitur as a Procedural Tool
It allows an inference of negligence to be presented to the fact-finder (jury).
The jury may accept or reject that inference.
It is based on circumstantial evidence — one fact (the accident) is used to infer another fact (negligence).
If all elements are satisfied, there is a material question of fact, and summary judgment is improper.
Why It Matters
Res Ipsa Loquitur is particularly helpful when:
The exact cause of the accident is unknown
The plaintiff cannot identify the specific negligent act
Expert testimony is often used in technical fields, like medical malpractice, where the patient cannot observe what went wrong during surgery.
Essentially, it allows plaintiffs to argue: “We don’t know exactly what went wrong, but it’s more likely than not that negligence caused this accident.”
