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 North Carolina, property owners can use 'No Trespassing' signs to deter unauthorized entry and reduce liability. Under North Carolina General Statutes (NCGS) § 14-159.12, 'No Trespassing' signs serve as a legal notice that entry onto the property without permission is not allowed. If a person enters the property after such notice has been given, they may be guilty of second-degree trespass, which is a Class 3 misdemeanor. Additionally, NCGS § 14-159.13 states that a person who remains on the premises after being notified by the owner or a representative to leave is also guilty of trespassing. Regarding liability, North Carolina follows the common law tradition where landowners owe a lower duty of care to trespassers than to invitees or licensees. Posting 'No Trespassing' signs can help landowners establish that individuals who enter the property without permission are trespassers, potentially limiting the landowner's liability if a trespasser is injured on the property.