Negligence

A person who owed a duty of care to another could be required to fulfil that pre-existing private law duty by the exercise of a public law discretion, but only if that might be done consistently with the duty-ower’s full performance of his public law obligations. That did not offend the principle that public bodies’ acts or omissions which were authorised by Parliament would not, though they cause injury, sound in damages recoverable by private law cause of action.

The demands of a private law duty of care could not justify, far less require, action or inaction by a public authority which would be unlawful in public law terms. The standard tests of legality, rationality and fairness had to be met as they applied to the use of the public law power in a particular case. If the case was one where the action’s severity had to be measured against its effectiveness, it had also to be proportionate to whatever was the