The police asked you for a polygraph test. Should you take it?

Polygraph tests — also known as “lie detector” tests — are controversial, at best. That doesn’t stop the authorities, however, from continuing to use them as part of the investigative process into crimes.

If the police ask you to take a polygraph test, it helps to understand more about your legal obligations and how the results can affect you.

Are you legally obligated to take the polygraph test?

No, you are not. Polygraphs have long been ruled inadmissible in court, which is why the court won’t issue a warrant for one.

If they’re inadmissible in court, do you have anything to lose?

You do. Here’s the problem: Polygraph tests are inherently flawed because they rely both on the examiner’s skill to detect small physiological differences that the machines picks up from the test subject as they answer real questions (as opposed to the “baseline” questions with known answers). That’s often a subjective evaluation — not ironclad science.

Plus, test subjects can have a variety of emotional reactions to the stress of the exam itself. Those heightened emotional reactions can translate into physiological signals that you are lying — even when you’re telling the truth.

That could make you look guilty when you’re innocent. While there’s no guarantee that passing the polygraph will get the police to look elsewhere for a target in their investigation, failing one is sure to put you in their crosshairs.

What should you do before you decide to take a polygraph?

You need to proceed very carefully here. You are clearly already a focus of any pre-arrest investigation that’s going on, and you should protect your interests. The wisest thing you can do in this situation is speak to an attorney before you commit to any kind of interview with the authorities — polygraph or not.