System and method for selecting location data to be used as the location of a user device using a location-based service. Horizontal location data and vertical location data for the user device are obtained from multiple sources. A horizontal location uncertainty and a vertical location uncertainty are determined or obtained for each source. In response to determining that both the horizontal location uncertainty meets a threshold horizontal uncertainty value and the vertical location uncertainty meets a threshold vertical uncertainty value, the corresponding source is identified as compliant. In response to identifying at least one compliant source, an optimum compliant source is selected to provide as the location of the user device using the location-based service.