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Using Polygraph for Criminal Cases

Tip Sheet - How Polygraph Can Assist A Criminal Defense Case

Polygraph examinations, which are commonly referred to as lie detectors, are often the best ways to tell if someone is actually telling the truth. Polygraph has become an icon of popular culture. There are now TV shows centered around lie detection and people are beginning to understand what those spiked readings mean. Here are three facts you need to know about polygraph:

  • According to the American Polygraph Association, polygraphs are accurate 90% of the time when properly administered by a trained professional.

  • In 1996, a study of criminal cases where lie detector was used, the control questions of the test were found to be 96% accurate.

  • Critics will say polygraph is about 70% accurate.

  • A polygraph test consists of only “yes” or “no” questions.

As a former investigator with 30 years of law enforcement insight, and an examiner who has performed thousands of polygraphs, I have found that lie detection can be a criminal defense attorney’s best friend. Client control and management is often a challenge among criminal defense attorneys. Some clients refuse to face reality – in the form of concrete, indisputable facts, confessions, and physical evidence.

Here’s where the polygraph examiner comes in. He serves as a neutral expert from the client’s point of view. The client realizes that the examiner is an advocate, does not negotiate with him and does not care whether he is telling the truth or not. But the client also knows if he’s lying, there’s a good chance he could get caught and will face the consequences.

Once a polygraph is administered, the veil is lifted. The client is in a better frame of mind to evaluate offers to settle, trial strategies and help his attorney build a better case. And the family of the client feels better because their loved one’s claims have been fully investigated and given their proper due.

The American Polygraph Association spent the past 15-20 years working to improve the accuracy of the testing. Their goal was to eliminate those techniques, that were less accurate and to have their members, only utilizing those techniques, that produced the results with the highest accuracy. Most criminal defense attorneys hold the belief that the evaluation of polygraph charts, is a very subjective undertaking. When in fact the scoring of charts is a completely scientific process, with very strict rules of what criterion is evaluated along with the manner in which it is evaluated.

The American Polygraph Association compiled 12 different studies utilizing in excess of three thousand separate real live tests that were conducted in the field. The evaluators of these charts were not the polygraph examiner, who conducted the actual testing, but an independent evaluator scoring the charts, with the same criterion and method of evaluation. As a result of this research, the American Polygraph Association no longer recognizes, many of the testing techniques that were being used in the field. To ensure that only tests that have the highest accuracy, are utilized by its membership, the Association only recognizes four techniques and their accuracy all exceed 92%. The Association will also revoke the membership of any examiner who does not follow these approved techniques.

Thus the accuracy of polygraph testing is far greater when utilizing a polygraph examiner who is a full member of the American Polygraph Association. In 1993 the U. S. Supreme Court also overturned its Frye Standard and replaced it with Daubert v Merrell Dow Pharmaceuticals. The Frye standard, which all courts used to exclude polygraph evidence, only utilized a blood pressure cuff, as it’s a method of lie detection. Not only are we light-years from those previous methods, we now have computerized polygraphs, in which the charts are scored utilizing a computerized scoring algorithm, developed by researchers from Johns Hopkins Medical School.

Here are golden opportunities for using polygraph for a criminal defense attorney:

  1. If you receive an offer from the prosecutor that states their intent to cease prosecution if your client passes a polygraph examination. This really is a good indication that they are searching for a way, to dispose of a weak case.

  2. If the prosecution or the police, ask your client to take a polygraph test. This is another indication of a weak case. However it could become stronger or they could bolster their position, with a lot of circumstantial evidence. Never send this client into such a test. It would be like sending a lamb to the slaughter. Even though the test would be inadmissible, your client could make incriminating statements, which would be admissible. Get a test done by a competent private polygraph examiner. He will tell you whether or not to allow such testing.

  3. When you have an obviously guilty defendant do not always count out the use of a polygraph. Many times the prosecutor has a good case but they want to ensure the conviction. They will be looking for the “kicker” in the case. What if your client is charged with capital murder, but he wasn’t the shooter. Perhaps he was only the driver. Have a private polygraph examiner test the client on his lesser involvement. If you get favorable results and you approach the prosecutor with the results and it jives with what they already know, you may have a bargaining chip. It’s according to how valuable he is, he may even get some kind of plea where he serves a very short sentence or even probation.

  4. What if a parent comes to you with their child who has had a problem at school that may have resulted in a suspension or expulsion? Here’s where polygraph can get to the bottom of the school’s claim.

  5. Another very frequent use of lie detection is used in relationships. If your client suspects his wife is cheating, advise him to get him or she polygraphed. Even if he or she is guilty, they may confess to something that will enhance your client’s position.

  6. If you have a business client, who has found that he has employees who are stealing. Here’s where he can find out how pervasive his problems are. These employees can legally be tested, not all the employees but those who could be doing the same thing. Under the Employee Polygraph Protection Act if you have a professional polygraph examiner who follows all the rules of this law the testing is legal.

  7. A polygraph is also an excellent tool for cases involving sexual harassment.

The uses of polygraph by attorneys are endless and is an invaluable tool that can be used to assist in many legal situations. To learn more about how your office can use polygraph for your clients as well as ways to cover costs visit us a call at 800-662-1571.


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