(forgetting, for a moment, one cost me a job-unfairly, I think, back-in-the-day!)
The polygraph is an instrument which measures things like heart rate, perspiration, breathing and sometimes other body activity over which the person measured has little or no control. A skilled operator (who should also be a skilled interrogator) uses these measurements to determine if a subject is telling the truth to certain, carefully worded questions. It is not a lie detector, but a truth verifier.
Prior to 1988, many private companies utilized a pre-employment polygraph test, to determine if a subject was generally honest before hiring. Some also used polygraphs post-employment, at random intervals, to see if anything had changed. In 1988, Congress passed legislation limiting the use of pre-employment tests, with the exclusion of persons in certain sensitive positions, security, police and a few other jobs. Some States followed suit.
Many private companies were put out of business.
Having worked for a private investigations/polygraph firm for a number of years, it was an interesting experience.
First, some of the polygraphers (many of whom were retired law enforcement) thought themselves superior to the lowly civilian private investigators.
Second, I observed on numerous occasions, polygraphers watching job applicants arriving for a test, and making disparaging remarks, even before the interview or test began!
“This guy has liar written all over him!”
Hardly a lack of bias going in.
There was also a polygraph school adjacent to and affiliated with the investigations/polygraph company. When I was first employed as an investigator, I was considering signing up for the school, thinking it might be an important addition to my investigative skills. After observing and hearing the polygraphers, my interest waned.
This is not an indictment of all polygraphers, but just an observation based on some of those with whom I had negative encounters.
I suspect some of the laws have changed post 911, what with more agencies tasked with protection of the Republic from terrorists and spies.
I hope the current crop of polygraph examiners are more professional than some I encountered back-in-the-day.
We need all the help we can get.