Polygraphs are also regularly used by law enforcement when interrogating suspects. In some places, they're used to monitor the activities of sex offenders on probation, and some judges have recently permitted plea bargains that hinge on the results of defendants' polygraph tests.

Are polygraphs still used by police?

US law enforcement and federal government agencies such as the FBI, NSA and the CIA and many police departments such as the LAPD and the Virginia State Police use polygraph examinations to interrogate suspects and screen new employees.

Why does law enforcement use polygraphs?

It's a prop used by law enforcement and some employers. They are a deterrent and in some cases, somebody who believes you can tell when they are lying are more liable to tell the truth.