Connecticut residents might be aware that the results of polygraph tests cannot be used in criminal trials because they are considered too unreliable. They may be surprised to learn that law enforcement still uses lie detectors as well as an equally dubious investigative technique known as Scientific Content Analysis. SCAN involves handing a suspect a pen and asking them to write down answers to a series of questions. Analysts then look at what suspects have written to determine whether they are being truthful.
The reliability of SCAN analysis is not supported by any empirical evidence, but the technique remains popular with federal, state and local law enforcement agencies across the country. The website of the company that developed the technique currently lists 417 police and military clients in the United States. SCAN proponents say the technique saves police time and money and is not designed to provide proof of guilt.
The company behind SCAN analysis says that the technique is accurate 95% of the time, but they do not back up this claim with verifiable data. Several evaluations of SCAN have been published in peer-reviewed journals. When these evaluations were scrutinized in 2016, a team of academics found that the technique was about as reliable as flipping a coin. Their findings were published in the scientific journal Frontiers of Psychology.
Individuals facing criminal charges who have done nothing wrong may believe that they have nothing to lose by cooperating with the police. However, experienced criminal defense attorneys would likely advise any person detained by law enforcement to say nothing and ask to speak with a lawyer regardless of their guilt or innocence. Attorneys may help ensure that interviews remain on track, rights guaranteed by the U.S. Constitution are respected, and unreliable techniques like SCAN analysis and polygraph testing are not used.