I have been amazed about the US series revolving around lie detection such as Lie to Me and The Moment of Truth. In those, the truth-by-science fetishism bothers me; the idea that one can detect a lie without errors is suspicious using machines or just watching facial expressions and body language.
Even when this premise (that one can detect lies without error) is contested in an episode of In Lie to Me, the way this is done is interesting. In that episode, the main character cannot spot lying of other character. The main character concludes that the lying character is psychopathic, because he did not react normal ways to the pictures (this is plausible hypothesis). After this, the main character assumes that this psychopath must be a serial killer (this suspicion turns out to be true later in the episode).
But, if all the people having psychopathic disorder would be serial killers, the world would be full of serial killers; it has been estimated that 1% of the whole population have psychopathic disorder (using Wikipedia as reference here, but I remember seeing the same figure in Grossman’s book On Killing).
Lie detection may work with average population, but how the lie detection work with certain pathologies? Do they have similar psychophysiology as a normal person? It seems that psychopaths have decreased fear responses. How about pathological liars (cf. people with gambling addiction do not have similar fear reactions to risky bets that average people; see Damasio, Descartes’s Error)?