If A claims entitlement to land and enters based on that belief, is he trespassing?

In the context of trespass, the critical factor is not the belief or intent of the person entering the land, but rather the legal right to enter that property. Trespassing occurs when an individual enters another person's land without permission, regardless of their subjective beliefs regarding ownership.

Even if A genuinely believes he has a right to enter the land, that belief does not provide a legal defense against a claim of trespass. The law operates on objective standards rather than subjective perceptions; therefore, A's good faith belief in his entitlement does not negate the fact that he is on someone else's property without permission.

This principle upholds the rights of property owners and maintains the sanctity of property rights, emphasizing that the legality of an entry depends on the actual permissions granted by the landowner rather than the occupant's belief or intentions.