Are Polygraph Tests Really Useful In True Crime?!

Polygraph tests or “lie detectors” sound like the perfect true crime shortcut: strap someone in, ask the right questions, watch the needles jump, and let the machine tell you who’s lying. In reality, they sit in a murky space between science and theatre. They don’t measure lies, they measure stress, heart rate, blood pressure, breathing, sweat, and then a human interpreter decides what those spikes mean, which makes them dangerously persuasive in interrogation rooms and almost useless in courtrooms.

In case after case, people have “passed” while hiding horrific secrets, and others have “failed” simply because they wer...