No trespassing signs can be useful to property owners—especially on large tracts of land or land that is not developed—to put persons entering the property on notice that the property is private property and if they do not have permission to enter, they may be committing civil and criminal offenses related to trespassing. In some states notice is required for a trespasser to have civil or criminal liability for entering the property without permission.

No trespassing signs may also protect a landowner against liability to a trespasser, as a lower duty of care is owed to trespassers in some states, and putting a person entering the property on notice that they are trespassing may strengthen the property owner’s defense against any liability claims if the trespasser is injured on the property.

In Utah, property owners can use 'no trespassing' signs to deter unauthorized entry and reduce liability. Utah Code § 76-6-206 specifies that a person is guilty of criminal trespass if they enter or remain unlawfully on property and are aware that they are not authorized to be there. The presence of 'no trespassing' signs can serve as notice that entry is prohibited, which is necessary for establishing that a trespasser knowingly entered the property without permission. Furthermore, under Utah's premises liability laws, landowners owe a lower duty of care to trespassers than to invitees or licensees. By posting 'no trespassing' signs, landowners can demonstrate that they have warned trespassers, potentially strengthening their defense against liability claims should a trespasser be injured on their property. However, the effectiveness of such signs in limiting liability may depend on the circumstances of each case and the application of Utah's comparative negligence rules.