So if these tests are so accurate, why aren't they required in every situation where truth is at issue? Why spend billions of dollars on jury trials and independent prosecutors when we could just "wire up" the key witnesses and get at the truth with no fuss and no muss?

Some people are so divorced from morality or a guilty conscience that they may test honest -- because they are really good liars or have convinced themselves of a truth that isn't the truth at all. It may also be possible to throw the results through other methods, such as yogic or biofeedback training, the "nail in the shoe" trick (putting a sharp nail in your shoe to cause yourself pain during the questions to skew the polygraph results), or using a legal or illegal drug to calibrate one's emotions. Simply put, there is no way to turn a lie detector test into a slam dunk. For this reason, most courts will not admit polygraph results unless both sides to the case agree.