In R v Shorrock, when can acts of a stranger be used as a defense in public nuisance cases?

In public nuisance cases, the defense involving the acts of a stranger is applicable when the defendant was unaware of the nuisance and could not have reasonably known about it. This essentially means that the defendant had no control over the situation and did not contribute to the creation of the nuisance through negligent or intentional behavior. Therefore, if the defendant had no knowledge of the acts contributing to the public nuisance and could not have taken any reasonable steps to prevent it, that can serve as a valid defense.

This principle underscores the importance of a defendant's state of mind and knowledge in nuisance law. If a defendant was completely in the dark about a harmful act that was committed by someone else, it's reasonable to argue that they should not be held liable for an issue beyond their control. This also aligns with the broader legal standard that seeks to apportion liability based on responsibility and contribution to the harm involved. Understanding this aspect is critical in differentiating between culpable actions and incidents completely outside one's awareness or influence.