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 Kentucky, property owners can use 'No Trespassing' signs to deter unauthorized entry and reduce liability. Kentucky law recognizes the importance of such signs to inform individuals that they are entering private property. Under Kentucky Revised Statutes (KRS) 511.080, it is a criminal act to knowingly enter or remain on someone else's property without consent when 'No Trespassing' signs are posted or the property is fenced. The presence of these signs can establish that a person has received notice that entry is not allowed, which is necessary for a trespass to be considered criminal. Additionally, Kentucky follows the common law tradition where landowners owe a lower duty of care to trespassers than to invitees or licensees. Therefore, if a trespasser is injured on the property, the 'No Trespassing' signs may help the landowner demonstrate that the trespasser assumed the risk of injury by entering the property without permission, potentially reducing the landowner's liability.