Wikipedia says: Under the attractive nuisance doctrine of the law of torts, a landowner may be held liable for injuries to children trespassing on the land if the injury is caused by a hazardous object or condition on the land that is likely to attract children, who are unable to appreciate the risk posed by the object or condition. The doctrine has been applied to hold landowners liable for injuries caused by abandoned cars, piles of lumber or sand, trampolines, and swimming pools. However, it can be applied to virtually anything on the property of the landowner.