D’s car was being used by her husband and he had been drinking and got a sober friend (C) to drive. The friend’s negligent driving led to P being injured and the husband killed. P sued D as the owner of the car (as well as administrator of her husband’s estate) on the grounds that C was her agent: she had told the husband to get a friend to drive if he was drunk. HL rejected P’s claim against D in this capacity, since to fix vicarious liability on the owner of a car, it must be shown that the driver was using it for the owner’s purposes under delegation of a task or duty; that the owner's interest in or concern for the safety of the car or its occupants was not sufficient. Therefore C wasn’t the wife’s agent.
Lord Wilberforce: To establish vicarious liability in such a case it has to be shown that C was using the car “for the owner's purposes, under delegation of a task or duty.” He rejects Denning MR’s idea in CA to substitute this “clear” test for a vaguer one of mere “interest”. Vicarious liability is grounded in the idea of respondeat superior- the owner ought to pay- because he has ordered the action. Here the owner had no control over the actor, C. Denning MR’s theory that the owner or hirer of the car is liable for all accidents that occur when it is under his control is wrong.