Sometimes when you are being investigated for a crime and the police have some questions as to whether or not you are responsible for what they are investigating, they may ask you to take a polygraph (lie detector) test. In answering the question as to whether you should take it or not we should first take a closer look at them and what they truly measure.
Lie Detectors Don’t Detect Lies
Essentially polygraph tests measure the indirect effects of lying. It will measure such things as blood pressure, heart rate, sweating and breathing patterns. The polygraph does not measure whether or not someone is lying it measure signs that could possibly indicate that someone is lying.
Are They Accurate?
Any number of factors can affect the accuracy of a polygraph test. That includes an instructor’s experience, the format of the questions and the ability of the instructor to read tests accurately.
One of the largest problems about polygraphs is that they in and of themselves can cause a tremendous amount of stress. This is especially true when someone is being asked about possible criminal charges. Therefore, the test may be good a detecting lying but, in many instances, may be very poor when determining if someone is telling the truth. That is someone lying and telling the truth may both be shown as being deceptive simply because the person telling the truth is under tremendous stress from just taking the test.
Are They Reliable?
It is estimated under ideal conditions a polygraph may be accurate 80 to 90% of the time. However, when it comes to determining someone’s guilt or innocence that simply is not good enough. An instrument, when operating under ideal conditions, that is wrong up to 20% of the time is simply to unreliable to be uses in any meaningful way to be admissible as evidence in a criminal case.
Should I Agree to Take the Test?
So, that takes us back to the original question. If the police ask me to take a polygraph should I agree? The simple answer is no, not without meeting with a criminal defense attorney first. If you have a negative result on a polygraph, remember false detections for lying are common, then the police will zero in on you when perhaps they should still be investigating other leads. In the alternative, you should speak with your attorney and discuss the benefits/risks of a polygraph in your situation. You may want to seek a private polygraph in order to understand the findings and lessen the preconceived stress that comes with a police administered test. Either way, talk to your attorney first!
If you or a loved one is under investigation for a criminal case, call the criminal defense attorneys at Banks & Brower at 317-870-0019 24 hours a day 7 days a week.