A reader wrote recently that he was denied a federal law enforcement job based on an inconclusive polygraph despite telling the truth, he said. He believes the N95 mask he was forced to wear during the examination is to blame.

The Goal of the Polygraph

Before we get into the details, let’s talk a little about what a polygraph examination actually measures. It is not a “lie detector.” It cannot detect lies. Polygraph examinations measure the movement of a subject’s body, breathing both in his or her chest and diaphragm, how much he or she perspires, blood pressure, and pulse. The idea is that by asking a series of questions to measure an examinee’s baseline, you know the physiological responses for truth and falsehoods. (This is called the “stim test.”)

Note that polygraph results are generally inadmissible in courts of law. In 1998, a majority opinion of the United States Supreme Court even mentioned that “there is simply no consensus that polygraph evidence is reliable,” and cited a study that stated polygraph results are “little better than could be obtained by the toss of a coin.”

According to the American Psychological Association, “although the idea of a lie detector may be comforting, the most practical advice is to remain skeptical about any conclusion wrung from a polygraph.” 


Polygraph examiners would disagree with such statements, but actual scientists would not. “Polygraph tests are not a valid technique to assess truthfulness,” says Len Saxe, a social psychologist and professor at Brandeis University who has studied polygraph tests for over 30 years. The fundamental problem, he says, is that there is no unique physiological response to lying.

Enter COVID-19. Civil servants of the federal government are required to enforce pandemic protocols. Chief among these requirements is the wearing of masks, and that includes during polygraph examinations.

I  reached out to intelligence community officials for comment on COVID-19 protocols for polygraph examinations, and for information on the scientific analyses of how mask protocols affect polygraph results. An intelligence official said: “In response to the COVID-19 pandemic, agencies with an approved polygraph program are taking the proper precautions to ensure they are following CDC guidelines and using PPE during all polygraph examinations. This includes wearing masks, cleaning equipment, and utilizing plexiglass during the examination process in order to protect both the polygrapher and the examinee.” My questions regarding the scientific scrutiny of how masks affect polygraph physiological responses were unanswered.


I have sterilized the below scenario recounted to me by a reader so as not to reveal, even obliquely, the person seeking help.

A law enforcement officer with more than a decade of experience applied for a job with a federal police force. He claims to have lived “a pretty boring life” and until the polygraph, encountered zero problems in the application process.  The first examination was inconclusive. “I admit I literally bared my soul for the examiner but he stated that I was doing something deceptive and that I had to have researched on how to beat it.” The reader claims to have done no such thing.

The second time he was examined, the results were the same, though he says “the examiner was more agitated and accusatory.” The examiners say his results were inconclusive on two different lines of questioning: he passed the questions with one examiner that he had not with the other, and vice versa.

He describes his experience as two full days of “torture,” and what feels like “a waste of time with no real answers.” Because I have written extensively about polygraph exams, he reached out to me for help. He just wanted to know what possibly could have happened.

Here is where it gets interesting: During these examinations, he was wearing an N95 mask.


Surely, a test designed to measure the most minute and subtle of physiological responses would be affected by a mask that restricts airflow. A study published in the Journal of the International Society for Respiratory Protection certainly suggests that masks like N95 filtering face piece respirators place physiological burdens on wearers, and particularly those with underlying conditions such as asthma or allergies.

I asked Dr. Saxe about this. He replied: “Wearing a mask or doing something else that would raise anxiety—perhaps reading or watching news—might or might not affect the physiological reactions measured by a polygraph. If it raised anxiety, that might make it more difficult to see response differences between questions.  But it’s an academic question since the test, itself, is not valid or reliable.”

Indistinguishable from Countermeasure

According to Kel McClanahan, a lawyer specializing in clearance matters, masks could cause all sorts of problems. “I wouldn’t even say that a sophisticated examiner could account for this by changing the baseline readings, because your body is going to be behaving differently to the stress of breathing through a mask, which will be picked up, and if you try to manage the stress, well, that’s indistinguishable from countermeasures as far as the polygraph training goes,” he says. “So you would have to be an absolute master polygrapher with hundreds of hours of ‘masked polygraph’ training in order to have anything close to the degree of confidence that they have in normal situations. And most polygraphers frankly aren’t trained that well to begin with.”

That being said, he explains, legal and appeal processes won’t do you again good if you actually did something wrong. “If he admitted to something after the examiner kept telling him ‘it’s still showing up as inconclusive,’ then that’s no different than before COVID,” McClanahan says. “Arguing that the mask led to the inconclusive reading won’t get you anywhere if you then admitted ‘well there’s this time I stormed the Capitol.’ But if they said you failed it because you were using countermeasures, then I’d totally argue the mask interfered.”

If you are facing a denial, you can appeal it, and it’s important to bring in experts to the process.


Even taken without a mask, the theater of the polygraph examination is enough to generate a few responses of their own: the examiner with his or her notepad, scribbling away, the tone in his or her voice, the skeptical repeating of questions, the very phrasing of those questions—it’s enough to get in an examinee’s head, and make the truth seem elusive. In short, once you feel like your honest answers aren’t being believed, you’re panicking and everything is turning into a train wreck of registered “lies.”

Given that polygraph examinations proport to measure unique physiological responses to lying, this is a problem! One expert quipped that intelligence agencies would be better off using tarot cards to assess truthfulness among candidates for security clearances. What seems to be the case is that the polygraph works best against people who believe the polygraph works, because they are more likely to fess up to transgressions.

Moreover, some unfortunate examinees are what are called “guilt grabbers.” These are people generally of extraordinary integrity, who fail examinations not because they feel guilty for doing wrong, but because they feel guilty for thinking about doing wrong.

Polygraph Failures Highlighted with Masks

In short, a test with no scientific underpinning and troubling margins of error even in the best of times are completely undermined by masks, already shown to disrupt the very physiological processes the test purports to measure. If the polygraph had trouble before, it now suddenly has even less credibility than a coin toss for determining “truthfulness.” The worst part about all of this is that the cleared workforce will suffer because of it. While we want to weed out the liars and those who are against the cause of national security, we also don’t want to lose good, law abiding citizens who want to support the U.S.

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David Brown is a regular contributor to ClearanceJobs. His most recent book, THE MISSION (Custom House, 2021), is now available in bookstores everywhere in hardcover and paperback. He can be found online at https://www.dwb.io.