<i>Clearly, such tricks may already be used by some expert 
detectives – but given the folklore surrounding body language, it’s worth emphasising just how powerful persuasion can be compared to the dubious science of body language.</i><p>It strikes me to the degree that the folklore is mixed with the (so called dubious) science.
I was always interested in the topic, and had indeed read a book when I was teenager, with ideas such as the iconic example of Clinton touching his nose.<p>About 5 years ago I went to the topic again; learned that one of the biggest authority in the topic was Paul Ekman and read a couple of his books<p>Surprise surprise, the main takeaways were ideas such as:<p><i>(...) not to jump to early conclusions: just because someone looks nervous, or struggles to remember a crucial detail, does not mean they are guilty. Instead, you should be looking for more general inconsistencies.</i><p>Or<p><i>There is no fool-proof form of lie detection, but using a little tact, intelligence, and persuasion, you can hope that eventually, the truth will out.</i><p>Ekman repeated all over the place that there is no body language for lies, only for emotions, and that the emotions can have a variety of causes.
And that was already clear the last century! 
If some security entity has bought something that promised to spot lies, it was probably folklore-based and no science-based.