You’ve talked to the police, who suspect you are involved with a crime. Now they want you to take a polygraph – what should you do? If you’ve already made one mistake – speaking to the police without an attorney – don’t make another by taking a polygraph without consulting an attorney. What is a polygraph? A polygraph is not a “lie detector,” although they are often called that. In the words of Wikipedia, a polygraph is a device that “measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions.” The polygrapher asks the subject of the polygraph questions, reviews the readings from the polygraph, and then renders an opinion about whether or not the subject is being deceptive. How they do so is both complicated and subjective, but for our purposes the important thing is that the result of a polygraph is – fundamentally – one person’s opinion. Are they reliable? No. At least, they’re not reliable enough to be used in court, and I wouldn’t want anything major in my life to turn on the results of a polygraph. I certainly wouldn’t want a polygraph to be the basis of criminal charges against anyone. Fortunately, they are generally not admissible in criminal cases in Kentucky. Polygraphs can and do produce false positives (indicate that there is deception when there is not). They can also produce false negatives (indicate there is not deception when in fact there is). If they’re not reliable, why do the police use them? Police use them for a couple of reasons. First, some officers and some prosecutors genuinely believe in polygraphy, and if they have concerns about their case they will be less likely to bring charges if a person “passes” the polygraph. Second, and much more importantly, polygraphs are a powerful interrogation tool. The polygraph as an interrogation tool As an example, imagine a case where there is no physical evidence. There really are “he-said, she-said” cases; let’s say someone alleges that another person threatened them but that there are no other witnesses or recordings. An officer might ask the suspect to take a polygraph. This takes a couple of hours, and the suspect will be answering a number of questions about the allegations against him. The polygrapher leaves the room to “score” the polygraph. He then comes back in and informs the suspect that he failed miserably. Next, he browbeats the suspect about what he knows and uses all of tools of the investigator’s trade (that’s a whole other topic). Significantly, the suspect frequently doesn’t know that the polygraph results are inadmissible, and now thinks that there is “scientific” evidence that he lied. For obvious reasons, many people in this situation cave and admit to crimes that they may or may not have committed. Should anyone take a polygraph? Yes, there are times when a person should take a polygraph. However, no one should ever take one without consulting an attorney first. When a new client tells me that the police want him to take a polygraph, the first thing I do is call the officer and tell him that my client will not be taking one without me being present. I then frequently have my client take a polygraph at my office; that is to say, we hire a polygrapher of our own to administer the test. If the result is favorable, I might then share it with the investigating officer or prosecutor. Other times, we arrange for the police to administer their own polygraph – with me present the entire time. If the results aren’t favorable, we do not share them with anyone, and we stop talking about polygraphs. Remember, polygraphs produce both false positives and false negatives – people who are telling the truth sometimes “fail” polygraphs. If you have questions or if you have a case that involves a polygraph, contact a lawyer at Edwards and Kautz to discuss it. We can be reached at 270-908-4914 or by filling out a form on our website.
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