Looks like polygraph exams are a good example of the 1% theory which states if there is a 1% chance of someone being guilty then they are guilty. ( or something like that) Maybe polygram exams have a chance of weeding out 1% of those who indeed are involved with harming national security, and those that are innocent (99%) are discarded because the supply of potential of future employees are unlimited. 

When we kill bad guys we kill the innocent also. This is just the price of doing business and the business is national security. It is the shame how the innocent always bear the burdens of those who desire to do evil.