When the Emergency Protocols had been invoked, military officials could authorise immediate executions. Computer software would search all communications for key words. When a Slitheen craft landed in the River Thames and the Prime Minister went missing, the Emergency Protocols were handed to Joseph Green or more precisely, the Slitheen posing as him. Jackie Tyler phoned the BBC's alien helpline and told them about the Doctor. The computer software detected this and the word "TARDIS", initiating a Code Nine. (TV: Aliens of London)