How accurate are polygraphs?
Even if you've never taken one, you probably know polygraphs are not admissible in court. The reason is that they are not considered accurate enough to be used in a court proceeding. That has been always been the law, even though some defendants have recently tried to get in favorable results.
For something that's not recognized as reliable, we place an awful lot of emphasis on them. District Attorneys routinely offer polygraphs, and agree to dismiss charges if the person passes. Generally those are cases where there is no physical evidence, and the case depends on witness testimony. Sexual assault cases are probably the most common. You can safely assume they wouldn't agree to do that if they didn't think they were reliable. The flip side is also true - if you fail, they have no doubt you are guilty.
A recent post contains an article that raises questions about just how accurate polygraphs. Apparently drug cartels are using polygraphs to sniff out undercover operatives. As a result, officers are being trained on how to pass a polygraph. There's no doubt these are highly trained officers, who have undergone a significant amount of training. The fact that they can do it though tells you something. At a minimum, it tells you they are not always accurate.
Even with their limitations, don't expect polygraphs to go away. We all want a quick, easy way to determine if someone is truthful. Even with all the advancement in science, we still can't uncover someone's thoughts. It's good to remember though that they are not always infallible, and not automatically assume someone is lying if they fail a polygraph.
