Computer Stress Voice Analysis.  How does this system work and is it comparable to a poly test?  I will have to take one.  I have tried marajuana in the past (high school) and will freely admit that.  The only thing I might be hesitant in answering correctly is if I have ever driven under the influence.  I have stupidly in the past and wonder if admiting can hurt my hiring chances.

Coup,

"Have you ever driven under the influence of alcohol?" is a common question on polygraph lie detection "tests."  You will be surprised to know, however, that this is not a relevant question (one where the polygrapher is trying to determine if you are truthful) on these "tests."  In actuality, law enforcement agencies (including the FBI) assume that everyone who admits to occasionally drinking alcohol has driven while under the influence.  Although the examiner will hype up this question in the pre-test interview and act like drunk driving is an automatic DQ, he actually assumes that you are lying to him when you answer "no."  He compares this reaction with your reaction to relevant questions like "Are you in violation of this agency's drug usage policy?" when making his simplistic and flawed determinations of truth and deception.  If you think this sounds warped, I agree.

For your own edification (if you are pursuing a law enforcement career you may one day face polygraph interrogation), I strongly suggest reading The Lie Behind the Lie Detector , which is available free on this site.  I also suggest reading the personal statement of "Captain Jones." 

CVSA, on the other hand, does not use control questions.  As George said, the (purported) technology is so unreliable that a vast majority of agencies simply use the device as an interrogation prop.  The key here is to make no damaging admissions.  Decide what you plan to admit before arriving for the “test” and do not change your story for anything.  In addition to The Lie Behind the Lie Detector , you may wish to peruse The Department of Defense Polygraph Institute Interrogation Handbook also available on this site.