A method and system for evaluating the validity of location fixes of a mobile station by comparison of a location fix for which a validity determination is desired with one or more prior reference location fixes. In one embodiment, a satellite positioning system based location fix of a satellite positioning system enabled cellular mobile station in a cellular communications network is validated by comparison of the satellite positioning system based location fix to one or more of a plurality of network based location fixes, or to an estimated future location fix of the mobile station.