Many of these experiments violated US law even at the time and were in some cases directly sponsored by government agencies or rogue elements thereof, including the Centers for Disease Control, the United States military, and the Central Intelligence Agency; and in other cases were sponsored by private corporations which were involved in military activities. The human research programs were usually highly secretive and performed without the knowledge or authorization of Congress, and in many cases information about them was not released until many years after the studies had been performed.