Trespassers - A trespasser is someone who is not authorized to be on the property at issue. Landowners are not obligated to protect trespassers who enter their property without permission, but they cannot willfully injure them. Also, if an owner knows, or should know, that there are frequent trespassers on his/her property, he will be liable for their injuries caused by an unsafe condition on the property if: 1) the condition is one the owner created or maintained; 2) the condition was likely to cause death or serious bodily harm; 3) the condition was such that the owner had reason to believe trespassers would not discover it; and, 4) the owner failed to exercise reasonable care to warn trespassers of the condition and the risk presented.

Trespassing children - A different rule applies where trespassing children are involved. In the case of children who wander onto a property without authorization, property owners do have a duty to ensure that their property is safe. The logic behind this exception is that children are sometimes naive to dangers on property, and could in fact be lured to dangerous conditions such as a swimming pool, an abandoned well, or heavy machinery. These potential hazards are referred to as "attractive nuisances." Thus, a property owner has a duty to inspect his/her property to see if there are any potentially dangerous conditions that might attract children and, if there are, act immediately to correct the unsafe condition(s). A property owner may be liable for an injury to a trespassing child if he/she knew, or should have known, young children were likely to trespass in the area of a dangerous condition on the property that involved an unreasonable risk of bodily harm to children, of which risk young children would not be aware, and when the utility of the condition is small compared to the risk it represents.