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 Kansas, property owners can use 'no trespassing' signs to deter unauthorized entry and reduce liability risks. Kansas law recognizes the importance of such signs to establish that individuals entering the property without permission are aware they are trespassing. Under Kansas Statutes, particularly K.S.A. 21-5808, criminal trespass occurs when a person enters or remains upon or in any land, non-navigable body of water, structure, vehicle, aircraft, or watercraft by a person who knows they are not authorized to do so, and it is marked clearly as private property with signs or fencing. The presence of 'no trespassing' signs helps to establish that the trespasser had knowledge of the trespass, which is a key element for both civil and criminal liability. Additionally, Kansas follows the common law tradition where a lower duty of care is owed to trespassers compared to invitees or licensees. This means that if a trespasser is injured on the property, the landowner may have a stronger defense against liability claims if it can be shown that the trespasser was adequately warned against entering the property through the use of 'no trespassing' signs.