The lawsuit is related to a traffic stop on Aug. 9, 2014 along Hwy. 80.
Forney police received a call about four men driving a tan car and waving a gun out the window.
Officers pulled over Kametra Barbour, who was driving a burgundy-colored car.
She and her three children were forced to get out at gunpoint.
The lawsuit claims Forney police were inadequately trained, and accuses the department of making several other wrongful stops.
The City of Forney refused comment due to pending legal action.