First Principles of Business Law

6. Causation

6.2.4. Combined causes of harm

Case study: While driving his car on a busy road, A exceeds the speed limit by 20 kms per hour. While rounding a bend in the road, A fails to keep to his side of the white line that marks the centre of the road. B, who is driving in the opposite direction, is too busy talking to his passenger to keep a proper lookout, and does not notice that a collision is about to happen until it is too late to avoid it. B is injured. Consider both of the arguments below. Which of them do you think is correct?

(a) A breached a duty of care to other road users, and this was partly the cause of B's harm. However, B's failure to keep a proper lookout was also negligent, and contributed to his own harm. In these circumstances A will be liable to B proportionately to the extent that A's conduct caused the harm to B.

(b) A breached a duty of care to other road users, and this was partly the cause of B's harm. However, B's failure to keep a proper lookout was also negligent, and contributed to his own harm. Because B's conduct contributed to his own harm, A is not liable to B.