Mullin v Richards [1998] 1 All ER 920 is a judgment of the Court of Appeal of England and Wales, dealing with liability of children under English law of negligence.[1] The question in the case was what standard of behaviour could be expected of a child.
The plaintiff and the defendant, two female friends of fifteen years old, were fencing with plastic rulers in their classroom. One of the rulers shattered and a piece of plastic flew into the plaintiff girl's eye, partially depriving her of sight.
The Court of Appeal found that the standard to be expected of a 15-year-old child was not the standard of a reasonable person, but that of a reasonable and "ordinarily prudent" 15-year-old. It was held that an ordinary prudent 15-year old could not have foreseen any injury when playing with rulers and the defendant was therefore found not liable in negligence.