In “Just Between Us Girls” – I mentioned how lie detector testing (the polygraph) served Isaiah and Darvie T quite well. It confirmed Isaiah’s comment that it “wasn’t Darvie” who committed armed robbery and attempted murder. And the case was dismissed.

When I was a State’s Attorney, the old saying was — if you’re innocent, take a bench trial (before the judge only). If you’re guilty take a jury trial. I have to wonder why more criminal defendants – who claim “innocence” – don’t agree to take a polygraph. It can be done publicly or privately — with results then shared with the prosecution.

Polygraphs normally measure four metrics: respiration; blood pressure; pulse; and skin conductivity (perspiration). They can be used in criminal cases but also in the private sector such as for job interviews. They are also used in matters relating to national security. The earliest truth detection device was developed in 1894 to identify changes in blood pressure. In 1904, breathing patterns were monitored and in 1921 these two metrics were combined. Skin conductivity and respiration were added in the 1930’s.

As to effectiveness, the American Polygraph Association suggests that 87 to 90% of tests have accuracy while third party investigations places efficiency at around 80%. They have been known to fail – but for the most part, they are reasonably accurate. Internationally, the polygraph is viewed differently as “truth” can vary depending on cultural norms.

For those who claim that they are not guilty in criminal cases, why not take a polygraph? But they rarely do. I have to wonder why. I’m just sayin’ . . . . .