who believes polygraphs are reliable?

I cannot tell a lie...or can I?

The federal government seems to think I cannot tell a lie during a polygraph examination without being caught in my lie. Joseph Stromberg at Vox.com tells us:

The FBI gives a polygraph test to every single person who's considered for a job there. When the DEA, CIA, and other agencies are taken into account, about 70,000 people a year submit to polygraphs while seeking security clearances and jobs with the federal government.

Obviously, we don't want liars working in law enforcement, so rooting out liars before we hire them is a good idea.

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.

Liars everywhere. Is a polygraph a good way to root them out?

As it turns out, no, it isn't. Polygraphs are not admissible as evidence in court and employers (federal government excepted) are banned from using polygraphs on employees.

And yet, the federal government and law enforcement rely heavily on polygraphs.Why is that?

One possibility is the belief that they're useful as a prop — part of what Saxe calls the "theater" of interrogation. "If the examiner does the theater well, and tricks the subject into believing that his or her lies can de detected, they might confess," he says.

 Related is the belief that polygraphs might be useful as a deterrent: if a sex offender believes he or she is going to be regularly subjected to accurate lie detection tests, committing a crime suddenly looks like a guarantee of heading back to prison. For both of these uses, it doesn't matter whether the test actually works or not, just that it's perceived as effective.

If it is interrogation theater, law enforcement may not really believe that polygraphs expose liars in any reliable way.

In fact, they are so sure that polygraphs are unreliable that they try to shut down people who teach how to control the outcome of a polygraph. If a polygraph could reliably identify lies, there would be no worries about someone teaching those countermeasures.

Instead, they worry.