Res Ipsa Loquitur

Res ipsa loquitur is an evidential doctrine that allows a court to infer negligence from the circumstances of an event even where the claimant cannot point to a specific act or omission by the defendant. In Thomas v Curley, the Court of Appeal explained the doctrine in these terms: the term res ipsa loquitur describes a situation in which it is possible for the court to draw an inference of negligence, where a claimant has proved a result without proving any specific act or omission on the part of the defendant which produced it.

The doctrine has conditions attached to it. The Court of Appeal in Thomas v Curley set these out: if it is proved on the balance of probabilities that the result could not have happened without negligence, and that the situation was under the control of the defendant, then it is open to the court to conclude that it is more likely than not that the result was caused by negligence. The court also noted the long-standing authority that it is not appropriate to draw such an inference where there is evidence as to why or how the result occurred.

The doctrine's practical reach, particularly in clinical negligence claims, has narrowed over time. The Court of Appeal in Thomas v Curley recorded that the Court of Appeal has made it clear that res ipsa loquitur will rarely be relevant in medical negligence cases, since claims are generally decided on the specific expert evidence about what did or did not amount to a breach of duty, rather than on an inference drawn purely from the fact that an adverse outcome occurred.