Yes, occasionally false positives occur, the vast majority of which are in the screening arena.  It's not 100%, but it is also not as antipolygraph types claim "little better than a coin flip".  Lives "ruined"? No, that's bullshit.  No one is "entitled" to government employment or a security clearance.  They are privileges, not rights.  If you don't get hired, your life is not ruined.  You find another job and move on. 

You anti types claim to help those who want to ensure they pass a preemployment poly, then claim you won't help a sex offender pass with the use of CMs.  How noble.  How naïve also, to think that visitors to this site who are rapists/child molesters/sex offenders will not use what they learn here.  Let ME ask YOU a question, one that I have asked George twice with no response:  how would you feel if a rapist successfully used CMs he picked up from this site or from Doug Williams to pass a criminal poly, and the victim of that rape was your wife/daughter/sister?  How would you like it then?