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 Minnesota, the use of 'No Trespassing' signs is recognized as a method for property owners to warn individuals against unauthorized entry onto their land. Under Minnesota law, specifically Minnesota Statute 609.605, trespassing can be a misdemeanor, gross misdemeanor, or felony, depending on the circumstances of the violation. The presence of 'No Trespassing' signs helps to establish that individuals entering the property are doing so without permission, which is a necessary element for proving a trespass. This signage can also play a role in limiting a property owner's liability toward trespassers, as Minnesota follows the common law tradition where a landowner owes a lower duty of care to trespassers than to invitees or licensees. By posting such signs, property owners make it clear that persons are entering at their own risk, which can strengthen the owner's defense in the event that a trespasser is injured on the property and attempts to hold the owner liable.