Comment by KingMob

No. They might believe it works quite well, though, but they're seriously mistaken.

My old neuroscience lab was approached 20 years ago by a three-letter agency looking to develop a rapid reaction time tool to measure the trustworthiness of new people in time-critical hostile situations.

Because of that proposal, I reviewed the literature on "lie" detector tests and their ilk. The evidence is great for them measuring stress, and flimsy for them measuring deception. Normal people get nervous when questioned. Psychopaths may show less autonomic responses. People can train to alter their stress levels. Data interpretation varies wildly by operator, as does accuracy. The only real value is trying to convince criminals they work, in the hopes they make a true mistake or confess.

tl;dr The accuracy is really low, and anyone arguing otherwise is trying to fool the criminals, trying to fool agencies into buying their equipment, or fooling themselves.