Saturday, May 05, 2012


Should you ever take a polygraph if asked to do so by law enforcement, an employer or that inquisitive airport security fellow who thinks the expensive green leafy substance known as Fortnum and Mason's tea you're bringing into London's Gatwick Airport is something smokeable? 
The first lie detector machine was invented in 1917 by William Marston who claimed he could reveal deception by observing levels of systolic blood pressure. It's not known by your favorite Pinellas Criminal Defense Attorney if Marston believed his claims as I've not had an opportunity to hook him up to one of the machines, but I do know that in 1923, that in Washington, an Appeals Court after lengthy tea fueled hearings determined that there was insufficient scientific evidence to support the lie detector's use in court.e. This decision is still enforce throughout the entire United States even in the Tampa Bay and Pinellas Criminal Court System in Florida, unless both the prosecution and the defense stipulate that the results of a lie detector can be used in court.
Today's polygraph machines record the involuntary physiological responses from the human body while being asked questions by an examiner and include measurements of not only blood pressure as in Marston's old method, but respiratory, cardiovascular, and sweat glands with the idea that jumps in physiological levels indicate deceitfulness rather than the long hidden, latent memories of unfortunate television choices while young which many of us still suffer from.

Happily for the guilty liars and Clearwater defense attorneys among us, there are some effective ways to distort the test by making the measurements meaningless:
1. take a few sedatives or a drink to reduce anxiety.
2. use an antiperspirant to prevent sweating - which come to think of it might be something you could  every day - remember this is legal advice from a Clearwater Criminal Lawyer and besides you might be near me in line. 
3. inflicting pain upon yourself with a pinch, a pin or a bite within your cheek for the entire questioning.

Or even better just don't take the test as studies show the polygraph test is unreliable and deceptive though in widespread use. Instead tell whoever wants you to take it to read this blog hourly and that the National Academy of Sciences conducted an extensive scientific review of the research on polygraph testing finding it to be unscientific because it had no established fixed standards, concluding that, "Almost a century of research in scientific psychology and physiology provides little basis for the expectation that a polygraph test could have extremely high accuracy....the inherent ambiguity of the physiological measures used in the polygraph suggest that further investments in improving polygraph technique and interpretation will bring only modest improvements in accuracy."
Polygraph equipment measures the variability of a person's heart rate, blood pressure and respiratory rate when asked a series of questions (see the Washington Post on Polygraph Evidence)
Reliability weak points
Body changes registered
by polygraph equipment
can be subjective to interpret, caused by
anxiety rather than guilt.
Heart rate fluctuations registered on a polygraph may indicate nervousness, not guilt.
A 2003 National Academy of Sciences panel found polygraph testing lacks sufficient scientific validity and accuracy to justify its use in screening federal employees but useful as an investigative tool. Several federal circuit and state courts deem polygraph evidence inadmissible.