Are polygraph test results admissible?
In my work as a Boston criminal defense attorney, I sometimes have clients ask me about the wisdom of taking a lie detector or “polygraph” test. Here is what you need to know.
How does a polygraph test work?
The polygraph test is based on the theory that lying is stressful, and that stress causes physical reactions which can be measured and recorded. The test uses sensors to record an individual’s breathing rate, pulse, blood pressure, and perspiration. The test begins with a few simple questions, such as name and birthdate, to establish the person’s physiological response when telling the truth. The questioner then asks more challenging questions, about the issues at stake in the case, to see if the individual’s physiological response changes.
Reliability of polygraph tests
Because its reliability is often in doubt, polygraph evidence has a long history of legal and scientific debate.
Supporters of polygraph tests claim they are reliable because:
- It’s hard for a person to control all the physiological functions tested simultaneously.
- Examiners run pre-examination tests that enable them to measure the individual’s reactions to lying.
- Many people, especially hardened criminals, can hide their stressful reactions to lying.
- A person’s stress may be caused by taking the test, rather than by a particular question or answer.
Admissibility in court
Federal courts will sometimes allow polygraph test results into evidence. For example, in the First Circuit Court of Appeals, which includes Massachusetts, polygraph results have been admitted into evidence and used in sentencing a criminal defendant.
Massachusetts state courts take a more hard-line approach. In 1974, Massachusetts first allowed polygraph evidence, but only to corroborate or impeach a defendant’s trial testimony. In 1989, however, the Massachusetts Supreme Court reversed this ruling and held that polygraph evidence is never admissible. The court determined that polygraph evidence suffers from serious flaws, including the subjectivity of the polygraph method, the unclear validity of polygraph evidence, and jury confusion.
If you or a loved one has been asked to submit to a polygraph test, you need to consult with an experienced Massachusetts criminal defense attorney about the specifics of your case, as well as the wisdom of submitting to a polygraph test. Call the Mahoney Criminal Defense Group, at (617) 492-0055, to schedule a free consultation. We represent clients in the Boston, Cambridge, Woburn, Somerville, Waltham, Salem and Lowell courts.
- Secretary Betsy DeVos: Slowly Remaking Title IX Investigations - August 2, 2018
- The Shooting of Kathryn Steinle - January 2, 2018
- Massachusetts House Passes Major Criminal Justice Bill - December 7, 2017