The invention relates to a method for operating an automated mobile system. The method includes determining a first trajectory based on driving environment data recorded by a sensor system of the system, determining at least a permissible second trajectory from a defined data source that is independent of the sensor system, comparing the planned, first trajectory to the at least one second trajectory, and, in response to a defined deviation of the planned first trajectory from the at least one permissible second trajectory, determining the first trajectory in a process modified in a defined manner. The invention also relates to a corresponding device.