For
They can help uncover the truth when evidence is unclear.
Against
They are unreliable and can be manipulated by stress or training.
Anonymous excerpts, translated where noted.
“I've had cases dismissed because of a polygraph.”
“I'd imagine they're quite useful in showing investigators what topics a suspect reacts to with stress.”
“There are very good liars that pass and there are innocent honest people who fail.”
“They are extremely unreliable which is why they are not admissible in court.”