Mark Harris in Wired:
CHRISTOPHER TALBOT THOUGHT he would make a great police officer. He was 29 years old, fit, and had a clean background record. Talbot had military experience, including a tour of Iraq as a US Marine, and his commanding officer had written him a glowing recommendation. In 2014, armed with an associate degree in criminal justice, he felt ready to apply to become an officer with the New Haven Police Department, in his home state of Connecticut.
Talbot sailed through the department’s rigorous physical and mental tests, passing speed and agility trials and a written examination—but there was one final test. Like thousands of other law enforcement, fire, paramedic, and federal agencies across the country, the New Haven Police Department insists that each applicant take an assessment that has been rejected by almost every scientific authority: the polygraph test.
Commonly known as lie detectors, polygraphs are virtually unused in civilian life. They’re largely inadmissible in court and it’s illegal for most private companies to consult them. Over the past century, scientists have debunked the polygraph, proving again and again that the test can’t reliably distinguish truth from falsehood. At best, it is a roll of the dice; at worst, it’s a vessel for test administrators to project their own beliefs.