Thanks for your response. I will certainly let you know what he says.

I don't know how big an issue your planned admissions will be. Your past drug use itself probably won't be a problem, but the revelation that you had concealed it might be. You may wish to check Security Clearances and National Security Information: Law and Procedures (17.5 mb PDF), written by Sheldon I. Cohen for the Defense Personnel Security Research Center, for any relevant information.

I'm not certain what paperwork you'll need to complete, but I note that Standard Form 86 (Questionnaire for National Security Positions) includes a question (#24) about illegal drug use "since the age of 16 or in the last 7 years, whichever is shorter":

http://www.opm.gov/forms/pdf_fill/SF86.pdf

If indeed you tell your polygrapher what you've learned about polygraphy, would you be so kind as to let me know how your polygrapher responds?

I am getting polygraphed and have a few questions.  I intend on telling the truth about past drug use which occured 15 years ago.  I didn't tell anyone about this other than my recruiter when I joined.  I did more tham Marijuanna and feel for sure that my clearence will be revoked. I plan on telling them that I know about polygraph(I have been reading your site), and that I know it is not scientific and that I know about countermeasures.  What are the chances that I will ever get my clearence back?  Will I be chaptered out of the army for my initial denials.  When I filled out the ESPQ forms everything was concearning the last 7 years?  Will the poly be the same?  Thanks for your reply.