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Should you take a lie detector test?

On Behalf of | Nov 1, 2023 | Criminal Defense

If you are being questioned regarding a crime, law enforcement may ask you to take a lie detector test. It’s important to understand that you are not required to do so.

In fact, there are several reasons why you probably shouldn’t take it.

The problem with lie detector tests

Because of their depiction in television shows and movies, people have been led to believe polygraph tests, also known as lie detector tests, are the primary indicators of truth. However, reality shows something different.

To understand their fallibility, it’s essential to know how lie detectors work. Lie detector tests measure physiological responses such as blood pressure, pulse, and respiration while a person answers a series of questions. The assumption is that deceptive answers produce different physiological responses than truthful ones.

However, several studies have shown these tests to be “junk science” due to their lack of reliability. One of the main issues is that they measure anxiety. An innocent person may exhibit stress simply because they are nervous about taking the test, while someone who regularly lies has a greater ability to control their responses. Furthermore, the lie detector test may produce false positives from a person with a mental health condition, such as obsessive-compulsive disorder (OCD) or generalized anxiety disorder (GAD).

Other factors can also skew the results of a polygraph test, such as:

  • The experience of the examiner
  • Medications
  • The test environment
  • Bias

Even with all the issues with lie detector tests, law enforcement still uses them during investigations. However, because of their unreliability, they have limited acceptance in the courtroom. Therefore, you should probably not agree to take a lie detector test if requested by law enforcement. It’s best to remember your Constitutional right to remain silent until you can discuss your situation with an eye toward your defense options.