Is a Polygraph Test Admissible as Evidence in Texas?

In nearly all cases, the answer is no. Despite the widespread use of polygraph tests in criminal investigations, these tests cannot be used to make a definitive determination that an individual is lying. What a polygraph does is measure minute physiological changes that the subject experiences while answering questions. These physiological changes can include a change in heart rate, increased sweating, and a rise in blood pressure. Although these can indicate that an individual is not telling the truth, they can also indicate nervousness or anxiety. Many factors can play into an individual’s polygraph test results, such as his or her emotional state at the time of testing, the individual performing the testing, and the way the questions are worded. Because of all the variables present that can alter a suspect’s results, most courts agree that polygraph tests are scientifically inaccurate. If you are a suspect in a criminal investigation and you are asked to take a polygraph test, do not take the test until you have discussed it with an experienced criminal defense attorney. You are under no legal obligation to take the test.

Should I Take a Polygraph Test?

You might think that taking a polygraph test will prove your innocence. Although volunteering to take a polygraph can be a tempting prospect, do not do it without consulting an experienced criminal defense attorney. There are certain very specific situations in which an attorney may recommend that a client submit to a polygraph exam for strategic reasons. A competent and experienced lawyer can advise you about the considerations involved including the information on plea deals, etc. A polygraph can complicate your case in a few different ways. If you “pass” the test, law enforcement could potentially assume that you somehow “beat” the test. If you “fail” the test, meaning that the test picked up on physiological changes that could be correlated with untruthful answers, this can make you appear to be guilty and make you a target for further scrutiny. Even if a police officer were to tell you that you should take a polygraph test, you are never required to do so. Since 1990, polygraph test results have been inadmissible in all Texas criminal courts with very rare exceptions. Your attorney can help you determine whether taking a polygraph test is a productive choice for you. And if your lawyer sends you for a polygraph, the results can remain confidential. A failed polygraph is not an automatic conviction. Likewise, “passing” a polygraph test does not mean that you can not be found guilty later.

McKinney, Texas Criminal Defense Attorneys

If you are involved in a criminal investigation in any way, be proactive and start working with a Collin County criminal defense attorney as soon as possible. Call Rosenthal Kalabus & Therrian today at (972) 369-0577 to begin working with a member of our firm. Our team of criminal defense attorneys can help you with your case by providing you with the legal counsel and representation you need. Do not wait to begin working on your case with our firm.


Written by: Rosenthal Kalabus & Therrian Last Updated : August 14, 2023