Mercer v Commissioner for Road Transport and Tramways (NSW)

The case of *Mercer v Commissioner for Road Transport and Tramways (NSW)* involved an appeal to the High Court of Australia concerning a claim for damages for negligence. The plaintiff, a passenger on a tram operated by the defendant, was injured when the tram collided with another tram. The collision occurred after the tram's driver collapsed at the controls, causing the tram to accelerate uncontrollably. The plaintiff alleged that the defendant was negligent in failing to install a safety device that would automatically stop the tram in such circumstances.

The central legal issue before the High Court was whether the defendant had acted reasonably in failing to equip its trams with a safety device, such as a "dead man's handle," which would have prevented the accident. The jury had found the defendant negligent and awarded damages, but the trial judge entered judgment for the defendant, a decision upheld by the Full Court of the Supreme Court of New South Wales. The High Court was required to determine if there was sufficient evidence of negligence to support the jury's verdict, or if the trial judge was correct in finding no evidence of negligence.

A majority of the High Court (Rich, Evatt, and McTiernan JJ.) held that the jury's verdict should have been entered for the plaintiff. Their reasoning was that the jury was entitled to find negligence based on the evidence presented, even though the defendant's practice was not to use such devices and expert witnesses testified to potential dangers. The majority emphasised that the general practice of those in the same trade does not necessarily negate negligence, and that a jury is not bound to accept expert evidence if it is not sufficiently persuasive. They found that the evidence regarding the potential dangers of the safety device was not conclusive and that the jury could reasonably have concluded that the defendant had failed to implement a reasonably safe system for controlling the trams.

The majority further reasoned that the jury's rider, which stated the defendant was not careless in the ordinary meaning of the word but justified in taking a remote risk, was not inconsistent with the finding of negligence. They interpreted the rider as distinguishing between general administrative carelessness and a specific failure to adopt a known safety measure. The dissenting judges, Latham C.J. and Dixon J., took the view that the overwhelming weight of expert evidence, which indicated that the proposed safety device was not in use elsewhere and could introduce other dangers, meant that the jury's verdict was against the evidence and should not stand. Ultimately, the High Court, by majority, reversed the decision of the Supreme Court and ordered that judgment be entered for the plaintiff.