Roy Moore Says He Took A Polygraph, But It Won't Tell Us Anything Because the Tests Don't Work

moore on stage
Then-candidate Roy Moore arrives on stage to speak about the race against his Democratic opponent Doug Jones on December 12, 2017 in Montgomery, Alabama. Moore lost the election. Joe Raedle/Getty Images

Roy Moore says he took a lie detector test after losing a special election to fill Alabama's vacant seat in the U.S. Senate. But polygraphs have long been questioned as a scientifically valid tool to determine if someone is telling the truth.

Moore claims that his lie detector shows that allegations that he sexually harassed and assaulted teenagers is false. In general, polygraphs are meant to work by measuring things like a person's blood pressure, breathing and heart rate, according to the American Psychological Association. People are then asked questions. Some of these are "control" questions; any changes observed in their vital signs while they answer is then compared to what's seen when they respond to key questions that people actually want to know.

However, the evidence behind these responses' connection to deception—and the evidence for polygraphs as a whole—is iffy at best. A report from the National Research Council concluded that the scientific evidence for polygraphs' accuracy is "scanty and scientifically weak."

It's also important to note that polygraphs are far from infallible. It's entirely possible that they can be outsmarted. A former Oklahoma detective named Doug Williams was arrested for coaching people to beat polygraphs. (Technically, as Bloomberg reported, Williams was changed with mail fraud and witness tampering.)

Some do argue that polygraphs do work; The American Polygraph Association, unsurprisingly, claims trained examiners have 90 percent accuracy rate. However, the Supreme Court is among those disinclined to take those numbers at face value. In 1998, Judge Clarence Thomas wrote that "there is simply no consensus that polygraph evidence is reliable." (The case was about whether polygraph evidence should be admissible in military court.) The American Psychological Association has also encouraged people to "remain skeptical" about the results from polygraphs.

The results of Moore's polygraph were filed as part of a lawsuit to block the results of the special election, according to The Hill. The test happened a few days after the election, according to Moore, a Republican, lost the election to Doug Jones by a margin of 1.5 percentage points. Moore has claimed that the results were tainted by voter fraud.

Despite Moore's legal challenge, CNN reported that his opponent, Doug Jones, is set to be certified as the winner of the election and the state's Senator-elect by the Alabama secretary of state on Thursday. This is the first time in 25 years that a Democrat will represent Alabama in the U.S. Senate.