Cops and spooks all over the world rely on a junk-science "walking polygraph" method to steer their investigation

SCAN (Scientific Content Analysis) is a lie-detecting method invented by Avinoam Sapir, a former Israeli spook turned polygraph examiner that involves picking out small textual details from writing samples to determine when someone is lying. Sapir has used his method to determine the veracity of the Book of Genesis, and to conclude that Anita Hill might be a secret lesbian and that James Comey was likely sexually assaulted as a child.

SCAN has no empirical support, and is so outlandish that it has hardly been studied by third parties at all. However, each time it was studied, it was found to perform no better than chance. For example, an Obama-era deep dive into investigation methods, the High-Value Detainee Interrogation Group, which drew experts from many fields who concluded that "SCAN did not distinguish truth-tellers from liars above the level of chance" and challenged SCAN's core assumptions, such as: "Both gaps in memory and spontaneous corrections have been shown to be indicators of truth, contrary to what is claimed by SCAN."

Despite this, SCAN is widely deployed in the US and abroad, with customers in "Australia, Belgium, Canada, Israel, Mexico, the Netherlands, Singapore, South Africa and the United Kingdom," and within dozens (if not more) of US police departments, as well as the FBI, the CIA and the DIA.

Why would a tool with "no empirical support" be so widely used by police departments and spies? The best explanation is offered by Northwestern University law prof Steven Drizin, whose research focuses on wrongful convictions: "A lot has to do with hubris a belief on the part of police officers that they can tell when someone is lying to them with a high degree of accuracy. Read the rest