b. Proof of breach
As a general rule, the plaintiff must prove, on the balance of probabilities, that the defendant breached his duty. In other words, the plaintiff must satisfy the court that their version of events is more likely than not to be correct.
In practice, this is often the most difficult part of a negligence claim, because the plaintiff may not know exactly what happened, may lack access to the relevant evidence, or may be unable to identify the precise act or omission that caused the accident.
That said, breach may be proved by direct evidence or by inference from the circumstances. Courts may infer negligence where the proved facts are more consistent with carelessness than with any non-negligent explanation. This is particularly important in accident cases where the surrounding circumstances strongly suggest that the defendant failed to take reasonable care, even though the plaintiff cannot point to the exact mechanism of failure.
A related evidential device is res ipsa loquitur, literally meaning “the thing speaks for itself”. It does not create a separate cause of action and does not reverse the legal burden of proof. Rather, it permits the court to infer negligence where the accident is of a kind that ordinarily does not happen without negligence, the thing causing the damage was under the defendant’s control, and there is no known explanation for how or why the accident occurred.
Classic examples include situations where objects fall from premises, machinery fails in an unexplained way, or a vehicle behaves in a manner that would not ordinarily occur if proper care had been taken. In such cases, the plaintiff may establish a prima facie case by relying on the occurrence itself and the surrounding circumstances. If the defendant provides no satisfactory explanation consistent with reasonable care, the inference of negligence may be enough to justify a finding of breach.
Once the plaintiff successfully raises the maxim, it creates an inference of negligence that the defendant must then attempt to rebut. To avoid liability, the defendant can:
- provide a plausible alternative explanation for the accident that does not involve his negligence; and/or
- show that he exercised all reasonable care in the circumstances, even if he cannot explain exactly how the accident happened.
However, once evidence is called by both sides and the facts are fully explored, the case normally returns to the ordinary question whether, on all the evidence, negligence has been proved. Res ipsa loquitur is therefore best understood as a common-sense mode of reasoning rather than a rigid doctrine. It assists the plaintiff in appropriate cases, but it does not relieve the plaintiff of the ultimate burden of proving breach.
There are also limited situations in which legislation alters the evidential position. Under section 62 of the Evidence Ordinance (Cap. 8), where the defendant has been convicted of a criminal offence arising out of the same facts, that conviction may be admissible in subsequent civil proceedings and may operate as strong evidence of breach, leaving the defendant to rebut its effect.
