The only civilization we know, our own, does not explicitly transmit, except for a few small efforts. Even these efforts, and certainly any attempt to expand them, are controversial. It is not even clear we would respond to a detected signal—the official policy within the SETI community is that " response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place." However, given the possible impact of any reply it may be very difficult to obtain any consensus on "Who speaks for Earth?" and "What should we say?"