Polygraphs are legally inadmissable in court anyway because they're not accurate enough. Lie detectors DO NOT work on psychopaths which means many liberals could spin lies to the outer planets and still pass a lie detector with flying colors.

Normally, when a person lies their conscience automatically physically causes a brief, tiny little glitch in the nervous system, which the machine picks up. But psychopaths, by definition, have no conscience so the machine doesn't detect anything, so it simply won't work on an actual monster.