The Amateur Auxiliary is an American amateur radio organization operated by the American Radio Relay League (ARRL) that is authorized and works in conjunction with the Federal Communications Commission (FCC). The Auxiliary consists of official observers who are volunteer amateur radio operators who mostly just listen. If the official observers hear something that, in their opinion, doesn't follow FCC rules, they will send a reminder postcard to the amateur station causing the infraction. Note that this is how amateur radio operators in the US try to self-police themselves. The receipt of an Official Observer card is merely a note from another ham radio operator and has no legal authority to it.