What "documented efffectiveness" are you referring to?

"Occasional" false positive?

...it is reasonable to expect even with optimistic assessments of polygraph test accuracy that each spy or terrorist that might be correctly identified as deceptive would be accompanied by at least hundreds of nondeceptive examinees mislabeled as deceptive  NAS Report

 You quote from the NAS report as if it were a bible.  I have made clear to GM the moderator as to why the NAS report is NOT a peer review study free of bias. I do not accept the variable in their equation that Hundred would be labeled for each correct hit. !!!  

How does it help the national security by relying on an UNRELIABLE process?

Accuracy is composed of both Reliability + other factors.  That the polygraph is spoken of by you and disdained by your personal dissapointment, or that of others; in that is is Not 100% is not reason enough for you to say get rid of it.  Neither Medicine, Aviation, or your own driving is 100% perfect 100% of the time.  In the year 2008, it IS the best we have, and fine minds continue to improve it as is the case for the other examples, except maybe your driving.

First step is to focus on the real "bad guys", and spend less time trying to defend a process that routinely eliminates honest, qualified, patriotic people, while at the same time let's people like Aldrich Ames sail through!

First, you can not offer up WHO the bad guys are, or offer a BETTER test to identfy same.  Until YOU can, the government will work with the best tools it has.  I have never understood why posters here think that your concerns about the processes have not been looked at, funded for same research, or debated; has ever taken place in government by both sides of the aisle.  It is you who assume the variable of ignorance upon government, and that ONLY you know the Truth about these subjects.  I think that is something a kin to a Cult-esque belief system, as ONLY your group has ever debated these things before.  Surprise !!!, such debate and progress has been taking place before you were even born.