Do government jobs spinal tap you? I'd hate to be disqualifed from a job based on experimentation when I was 17.
Certain agencies require no drug use in the past 10 years and confirm with polygraph.
or ever for the FBI and certain specfic drugs
Correct, but the reality is that most agencies won't ever check. The FBI will poly you for certain job positions, as will many intelligence and other agencies. However, the reality is most just have you represent on a form your drug history and if you don't mention it, nobody knows. I'm not advocating lying, but it happens all the time.
Regardless of your past, there are plenty of agencies where you can get hired, be 100% honest, and go on to a long, fulfilling career.