A system for determining the potential for a possible cut-in situation by a cut-in vehicle on a subject vehicle. The subject vehicle may employ various devices, such as cameras, sensors, wireless communications systems, map data bases, navigational systems, etc., for detecting the cut-in vehicle, the possible movement of the cut-in vehicle, merge signs and other factors. The system can use this information in combination with collision avoidance systems or adaptive cruise control systems to take preventative action in the event of a potential cut-in situation.