They don't rely on drug tests for past use
They rely on interviews with friends and family to tell them about your use. They only do those interviews for Top Secret level, and even there they apparently weren't that extensive (based on what those who were interviewed about me said they were asked)
I assume the really in depth interviews are for the SCI codeword programs beyond Top Secret, about which I have no knowledge/experience. The information I was exposed to marked Top Secret was pretty mundane, so I think you need to go beyond that to get the good stuff. And knowing the government, the REALLY good stuff may well be at some even higher levels about which the acronym itself is classified...
Biting the hand that feeds IT
