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 Michigan, property owners can use 'no trespassing' signs to deter unauthorized entry and reduce liability. Michigan law recognizes the importance of such signs in establishing the private nature of property. Under Michigan Penal Code Section 750.552, trespassing on property without permission is a criminal offense, and the presence of 'no trespassing' signs can serve as notice that entry is prohibited. This can lead to civil and criminal liability for those who choose to ignore the signs and enter the property without consent. Furthermore, Michigan follows the common law tradition where landowners owe a lower duty of care to trespassers compared to invitees or licensees. By posting 'no trespassing' signs, landowners may strengthen their legal position by demonstrating that they took reasonable steps to warn against entry, which can be a factor in defending against liability claims should a trespasser be injured on the property. It is important for property owners to ensure that their signs are visible and placed at regular intervals to effectively communicate the private nature of the property.