Old_Geezer - // Ask Boris to take a lie detector test. //
That would be pointless, which is why they are admissible in court evidence.
A lie detector only indicates when a person believes that they are lying, it is no indicator of whether or not what they are saying is true or not.
That means that a Flat Earther, when asked if the earth is flat, will say 'Yes', and pass a lie detector, because they believe that it is, so for them it is the truth, even though it is a proven fact that what they believe, is not actually true.