At some point in a criminal investigation, law enforcement officers may ask you to take a polygraph test, also known as a lie detector. Many people will agree, thinking they have nothing to hide.
But taking that lie-detector test can be a big mistake and actually work against you.
Why some people think lie-detector tests are “junk science”
Polygraph tests can’t definitively tell when a person is lying. Instead, they measure physiological responses such as heart rate, blood pressure, respiration and skin conductivity. The assumption is that these responses indicate deception.
However, these indicators can be affected by a wide range of factors, including anxiety, fear, medication, environment and physical discomfort. In fact, lie-detector tests tend to produce false positives. There have been several instances where truthful individuals are incorrectly identified as deceptive. This can have devastating consequences. In recent years, many people who were wrongfully convicted based on their polygraph results have been exonerated when DNA and other evidence have proven them to be innocent.
Another issue with these tests is the evidence that suggests people can learn to manipulate their physiological responses. Through techniques such as controlled breathing, mental exercises and physical movements, they can skew the results.
The reliability and objectivity of polygraphs also arise from inconsistent results based on who is conducting the test. Different examiners can get varying results due to their methods, questions and interpretations.
In Michigan, the results of a polygraph are not admissible in court. Participating in one can potentially create legal complications. Furthermore, under the Fifth Amendment of the United States Constitution, an individual has the right to remain silent and can refuse to answer any questions or provide information that could incriminate them. However, it should be noted that submitting to a polygraph doesn’t violate the Fifth Amendment in most cases.
If law enforcement asks you to take a lie-detector test, you should refuse until you can speak with someone who can review your case and help you decide what is the best choice for your defense.