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Res Ipsa Loquitur
Res ipsa loquitur is a Latin phrase meaning 'the thing speaks for itself,' used in negligence cases when the accident itself strongly suggests someone was careless, even without direct evidence of the specific fault.
What it actually is
It is a rule of evidence that allows a jury to infer negligence from the mere occurrence of an accident if the harm ordinarily would not happen without negligence, the defendant controlled the instrumentality, and the plaintiff was not at fault. This doctrine appears in personal injury trials when direct proof of a defendant's breach of duty is unavailable, shifting the burden of producing an explanation to the defendant.
Why it matters in your case
For someone in a lawsuit, it can help overcome a lack of eyewitnesses or direct evidence by letting the accident's circumstances alone raise an inference of negligence. Practically, it may force the defendant to offer a non-negligent explanation or risk losing the case, though it does not automatically guarantee a win.
The common misunderstanding
Many people mistakenly think res ipsa loquitur automatically proves negligence, but it only creates a permissible inference that the jury may accept or reject. It also does not shift the ultimate burden of proof; the plaintiff still must persuade the jury by a preponderance of the evidence.
Get the actual rule
Definitions are orientation; rules are authority
This page explains the concept. When it matters to your case, read the rule that governs it in your court — we hold Texas, federal and Washington court rules word for word, and every state's official resources are on the state pages. If someone cites a case at you, check that it exists first.
Related
Terms that travel with this one
General explanation, not legal advice, and not specific to any state — procedures and deadlines vary by jurisdiction and court. If you can get a lawyer or free legal aid, do: every real option.