Lie detector
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A lie detector could detect if the subject was being untruthful.
Noah used a lie detector on River Song shortly prior to the Nerva Beacon's departure from Earth's space. (AUDIO: Last Words [+]Loading...["Last Words (audio story)"])
Anya Kingdom used a lie detector on Ellasi Craig to determine whether or not she was a Dalek agent. The detector confirmed that she was not. (AUDIO: The Dalek Protocol [+]Loading...["The Dalek Protocol (audio story)"])
The Judas Gift was a Draconian lie detector. (AUDIO: The Judas Gift [+]Loading...["The Judas Gift (audio story)"])