What is a polygraph?

You have seen them on TV and heard stories; but, what are they really?

A polygraph is a device that measures the body’s responses during an interview.  It measures the changes in respiratory, sweat gland, and cardiovascular activity during one’s answers to various relevant and irrelevant questions. The difference between deceptive and non-deceptive answers is not always as apparent as on TV.

Are they accurate?  No one really knows.  Some suggest they are 85-95% accurate. Yet polygraph results are not admissible in court.

So why use them?  In criminal cases, they are an investigative tool.  Usually, during a polygraph exam, a suspect is taken into a room without counsel and put through 1-2 hours of interrogation.  The examination and interviews are rarely recorded.  The process is unnerving regardless of one’s guilt or innocence.

What about private polygraphs?  Most police and prosecutors will not accept them even if they are administered by retired police polygraphists on the same equipment.  This is curious considering polygraphs are allegedly reliable. Maybe the true reason behind their use is to intimidate a suspect.

If you have been asked to take a polygraph, you should consider speaking to an attorney beforehand.  Anything you say during this unrecorded and private examination could be used against you in court however the examiner decides to recall what you said.