Are Lie Detector Tests Admissible as Evidence in Texas Criminal Courts?

man taking oath of honesty in court

Lie detector tests, which are also referred to as polygraphs, can be useful tools for assisting the investigator in deciding the right course of action. But are lie detector tests actually admissible as evidence in Texas criminal courts?

Many people think that criminal courts in Texas can rely on polygraph tests to prove a defendant’s guilt and secure a conviction. However, the answer might surprise you. If you are being investigated for a crime in Texas and law enforcement or a prosecutor asks you to take a lie detector test, do not agree to take the polygraph test without first consulting with a Georgetown criminal defense attorney.

How Lie Detectors Work

While most people have seen lie detectors in movies and TV shows, but not everyone understands how lie detectors work. A lie detector test is administered by attaching the polygraph machine to a person’s body.

Once the machine is attached, the examiner who administers a lie detector test asks the suspect a series of “yes” or “no” questions, usually starting with questions about the person’s name, age, and other basic questions.

As the suspect answers the examiner’s questions, the polygraph machine measures the assesses three indicators of the suspect’s physiological changes:

  1. blood pressure and heart rate

  2. respiration

  3. skin conductivity

The goal of the lie detector test is to determine if the suspect is telling the truth or lying. Many courts and investigators frown upon the use of polygraph machines due to their questionable accuracy.

A lie detector test could produce false-positive results if the person attached to the polygraph machine is nervous, which increases their blood pressure and respiration. The machine may think that the person is lying when he/she is actually telling the truth.

Some police departments use polygraph machines to seek confession from suspects. However, due to the fact that lie detectors are not the most reliable tool, lie detector test results may not be admissible in court.

Are Lie Detector Tests Admissible in Texas Courts?

A handful of states still consider lie detector tests to be admissible in court, while the vast majority of states do not treat the results of polygraph tests as admissible evidence in courts.

In fact, most states that consider lie detector tests admissible require the suspect’s consent before the results of the test can be submitted to the court. It is also important to mention that in most cases, lie detectors are used in civil cases rather than criminal cases.

According to the Official Website of The City of Austin, “polygraph results are not admissible into a court of law” in Texas. However, the website adds that if the suspect’s confession is lawfully obtained after administering a lie detector test, it may be used as admissible evidence in a criminal case. However, the court may subpoena the examiner who administered the test to testify about the confession.

When Lie Detectors Are Not Admissible in Courts

Lie detector tests are not admissible in courts in any of the following situations:

  1. State law does not consider lie detectors to be admissible evidence;

  2. The suspect did not consent to the test;

  3. The use of the test is prohibited in a specific situation; or

  4. A judge refuses to consider the lie detector test as admissible evidence in a specific case.

Lie detectors may not produce accurate results when the are defects in the polygraph machine or the examiner who administers the test is biased, not to mention that lie detectors assess the person’s psychological responses that are not necessarily an indicator of guilt.

In addition, law enforcement officers know plenty of tactics to abuse the polygraph machine. For example, an examiner may prolong the amount of time the test is administered to obtain a confession. However, many of these tactics constitute a violation of the suspect’s constitutional rights.

Should You Take a Lie Detector Test?

Lie detector tests are not admissible in Texas courts, and law enforcement cannot force you to take a polygraph test against your will. Besides, you need to keep in mind that you are innocent until proven guilty, which means you have no reasons to take a lie detector test to prove that you are not guilty.

If a suspect agrees to take the test, a law enforcement officer administering the test must read the suspect his/her Miranda rights before asking any questions.

The law does not require you to take a polygraph test, so why would you agree to the polygraph machine in the first place? If you are being asked to take a polygraph test, do not hesitate to contact your criminal defense lawyer.

It is not advisable to take a lie detector test without first talking to your attorney. If law enforcement officers want to ask you questions, you can refuse to answer any questions by taking advantage of your right to remain silent.

But what about taking a lie detector test to prove your innocence? Would that be a good idea? Not really. It is not recommended to take a lie detector test under any circumstances, even if you want to prove your innocence and know that you are not guilty. As mentioned earlier, polygraph machines are not the most reliable tools to check whether or not a person is telling the truth.

You do not know how the test might go. The device might produce a false-positive result and give law enforcement more grounds to pursue criminal charges against you.

Speak with an Experienced Criminal Defense Attorney

If you are being asked or even forced to take a lie detector test, it is in your best interests to contact a skilled criminal defense attorney to protect your rights. Many law enforcement agencies and officers still use polygraph machines as a way to get suspects to confess. Lie detector tests are a powerful psychological weapon in the hands of law enforcement.

Do not fall into their trap by agreeing to take a lie detector test. Lie detector tests are not admissible in court, and you have a right to refuse to take the test. However, it is still a good idea to consult with an attorney to discuss your unique case.

Schedule a free case review with our criminal lawyers at The Law Office of Brett H. Pritchard to talk about your case. Call (254) 220-4225.
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