I have been watching the Casey Anthony case on TV. It has occurred to me that if Polygraph is as accurate as it's proponents claim and is, wouldn't it be great if we could just hook her up to a machine and see if she's lying. This of course would be great of so many other people as well; Lawyers, Politicians, Doctors, Teachers, Daycare providers and the list goes on.

How wonderful it would be to indeed have a machine that could detect lies. Just think, lying would be eliminated as we know it.
But alas, such a machine does not exists and according to the experts we have no way to accurately and reliably measure any physical responses as they pertain to deception including the use of Polygraph.

The fact that Polygraph as currently and previously used is a useful tool in obtaining confessions of the guilty ( and sometimes false confessions ) is no verification that Polygraph works as claimed.