Instead they have relied on selective personal testimonials on how they can be used to obtain confessions, while the routine failure of the device as a lie detector is overlooked.  Are confessions the same as validity?  Hardly.  For years cops used to get confessions from suspects with all kinds of lie detector ruses, like wiring a naïve suspect to a photocopier, or using the old Motorola radio in their squad cars that could change a red light to green when the mike button was pressed.  And, a phony ploy works only so long before people catch on.