A polygraph is a lie detector test. The theory behind a polygraph is that through physiological signs such as blood pressure, heart rate, etc. a machine can tell if a person is lying. It's a pseudoscience. Innocent people fail polygraphs and guilty people pass them. They are not scientifically reliable. The existence and results of polygraphs have never been admissible in court for any purpose, until now...
On March 7, 2012, the Court of Criminal Appeals decided Leonard v. The State of Texas. Mr. Leonard had been placed on probation for injury to a child, a non-sex offense. However, as a condition of his probation he was required to participate in some sex offender conditions. One such condition was that he complete sex offender treatment and show no deception on polygraph tests. As you may have suspected Mr. Leonard failed a polygraph test and as a result did not successfully complete sex offender treatment. He was otherwise perfect on probation. However, the State filed a Motion to Adjudicate. The trial judge found him guilty on that basis and sentenced him to 7 years in prison.
Mr. Leonard appealed on the basis that polygraphs have always been deemed inadmissible for all purposes. The Court of Appeals agreed and reversed. However, the State of Texas appealed to the Court of Criminal Appeals.
The Court of Criminal Appeals reversed the Court of Appeals. The decision, from the highest criminal court in the State, completely reverses course with all other Texas decisional law holding polygraphs inadmissible for any purpose. The CCA now says that polygraphs exams are admissible in probation hearings because probation hearings are just "administrative proceedings."
As you might imagine, this opinion is very troubling. The CCA didn't find polygraphs to be scientifically reliable or sound at all. Instead of attempting to do that (an impossible feat) the CCA just made an exception for their admission - "administrative [probation] proceedings." What's next? This is a slippery slope for sure.
Let this be a lesson - don't ever agree to take a polygraph.