Black helicopters are part of a conspiracy theory that claims that special silent running "black" helicopters are used by secret agents of the New World Order, United Nations troops preparing to invade the United States of America, and/or the Men in Black. Parapsychologist John Keel has argued that this theory has similar origins to those regarding UFO's, ghosts and fairies; that they are part of modern mythology; in this case, representing a fear of the government and its technology.
Black helicopters without FAA-required running lights are regularly used by the drug interdiction office DEA. In addition, most US Army helicopters (such as the Black Hawk) are finished in a very dark chocolate or olive matt paint. With the progressive development of night vision goggles, the need for helicopters to be lit when moving as a planned formation has been reduced.
See also: TACMAR
in short, any farfetched theory concerning any government or other conspiracy, can be espoused by either those of right or left wing persuasions.
Noam Chomsky's theory about Soap operas being geared to lure women from politics sure is a black helicopter theory.