(b) Public nuisance
Pages 2

Sachs LJ:… When looking at authorities concerned with highway nuisances, it is important to remember that there are these two categories, because otherwise phrases relating to the second-danger-category may be read as necessarily applying to the first-simple obstruction. It is, however, prima facie common to both categories-which can in fact overlap-that in neither is it necessary to prove negligence as an ingredient…that in both proof of what is prima facie a nuisance lays the onus on the defendant to prove justification (compare Southport Corpn v Esso Petroleum Co Ltd); and that, of course, neither is actionable-in the sense that a claim for damages can succeed-unless the plaintiff can establish that damage has actually been caused to him by the nuisance.