What must A demonstrate to avoid liability for damages when entering B's land?

To avoid liability for damages when entering B's land, A must demonstrate that the entry was necessary to prevent significant harm. This reasoning aligns with the legal concept of necessity in tort law, which recognizes that a person may enter another's land without liability if it is necessary to avert a more serious harm.

In this scenario, if A's entry onto B's land was essential to prevent imminent danger or significant harm—such as a fire spreading, a medical emergency, or a similar urgent situation—A may be justified in their actions. The necessity serves as a defense to trespass, as the harm avoided must be greater than the harm caused by the trespass.

Demonstrating that the entry was for personal benefit, that it was done with express permission, or that it did not cause any damages does not satisfy the legal threshold for avoiding liability in the same way that necessity does. While express permission could indeed negate liability, it is a different defense and not always applicable. Having no damages caused might also not absolve A from liability if the entry was unauthorized. Therefore, necessity stands out as the most compelling and universally recognized justification in tort law for entering someone else’s property without prior consent.