Can a Lie Detector (Polygraph) Test Be Used in Michigan Trials?

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Lie detector tests, also known as polygraph tests, have long been a fixture in popular culture, often portrayed as the ultimate truth-seeking tool. However, their use in legal proceedings, particularly in Michigan trials, is more nuanced than what movies and TV shows depict. While they can be useful in some cases, they are by no means universally accepted or correct. 

If you’ve been offered to take a polygraph test or want to take one to prove your innocence in a Michigan trial case, you first need to learn how it works and what could happen. Most importantly, you should consult with a defense lawyer before considering one.

A Brief History of the Polygraph

The polygraph has a rich history dating back to the early 20th century. It was first developed as a medical device that monitored cardiovascular activity. Later when scientists tried to link vital signs to emotions, it developed into a tool for detecting deception. Over time, its usage expanded beyond law enforcement to include employment screenings and even private investigations. However, its reliability and accuracy have been subjects of ongoing debate within the scientific community and the legal sphere.

How Does a Polygraph Work?

A polygraph measures physiological responses such as heart rate, blood pressure, respiration, and skin conductivity, which are believed to fluctuate when a person is being deceptive. During an examination, the subject is asked a series of questions while sensors monitor these physiological indicators. A baseline is established during control questions, and deviations from this baseline are interpreted as signs of deception.

At the end of the test, there can be four possible outcomes:

  1. No Significant Response, indicating truthfulness.
  2. Significant Response, suggesting deception.
  3. Inconclusive, when the data is unclear.
  4. Incomplete, meaning the test was not finished.

How Polygraphs are Used in Criminal Law Investigations

Criminal investigators offer polygraph examinations for various reasons, such as: 

  • Seeking admissible confessions from suspects or defendants 
  • Ruling out potential suspects in a crime
  • Gathering additional information about a crime
  • Verifying aspects of an investigation
  • Encouraging cooperation from individuals to leverage against other defendants, and
  • Conserving resources by assessing questionable or suspicious cases.

Polygraph tests in criminal investigations are voluntary, protected by the 5th and 14th Amendments. The person who will be interviewed will typically be read their Miranda Rights and asked to sign a form containing these rights. They must also waive their right to an attorney and be alone with the examiner during the test. If they do not follow this protocol, the test results will be invalidated. 

If you’re told you failed a lie detector test, refrain from answering more questions or making additional statements. Ask for your attorney to be present during further questioning and leave when possible. Avoid taking a polygraph if you’ve committed a crime, hoping to pass—it’s not a reliable strategy.

Can a Polygraph Test Be Used as Evidence in Michigan?

While some states allow polygraph evidence under certain circumstances, Michigan courts typically do not admit polygraph results as evidence. The reasoning behind this decision lies in concerns over the test’s reliability and the potential for false positives or false negatives. Therefore, relying solely on a polygraph test to prove innocence or guilt is ill-advised.

However, anything said during a polygraph test can still be used against you, no matter what the test results may show. If you make a confession or admission in a polygraph test, the examinor may be called to testify against you. The fact that your statement of admission was made during a polygraph test need not be stated, because that information is inadmissible. A request to prevent the statement from being used in court, known as a motion to suppress, is unlikely to be granted due to the waiver of Miranda Rights before the test was conducted.

Why Talk to a Defense Lawyer First Before Taking a Polygraph Test

While polygraph test results are typically not accepted as evidence in Michigan courts, they can still impact investigative and prosecutorial decisions.

Because of this, hiring a skilled defense attorney is one of, if not the best step to take before even considering taking a polygraph test. A skilled lawyer can provide invaluable guidance on the potential consequences of taking a polygraph test and advise on the best course of action based on the specifics of your case. Additionally, they can also guide you on the process of taking a polygraph test if it proves to be a wise choice for your specific situation.

While lie detector tests may hold intrigue in popular culture, their utility in Michigan trials is limited. Understanding the history, functionality, and legal implications of polygraph tests is essential for anyone facing legal challenges. If you find yourself in such a situation, don’t hesitate to reach out to Duplessis Law for expert legal representation. Our experienced team is here to protect your rights and ensure the best possible outcome for your case.