If you are under investigation for a sex crime in Harris County (Houston) or anywhere in Texas, you might be asked to take a polygraph test (a.k.a. “lie detector test”). The request might come from a police detective, the Texas Department of Family and Protective Services (DFPS) or Child Protective Services (CPS). While it is natural to want to clear your name quickly in a sex crime investigation, there are at least three (3) reasons why you should never take a government-sponsored polygraph examination, unless a criminal defense lawyer advises you to do so. The first reason is that an innocent person can fail a polygraph test. According to a report from the National Academy of Sciences, “[a] variety of mental and physical factors, such as anxiety about being tested, can affect polygraph results – making the technique susceptible to error.” Unfortunately, once you have failed a government polygraph test, there may be little you can do to convince the police, DFPS, CPS or a state or federal prosecutor that you are innocent.
A second reason why you shouldn’t take a polygraph test unless your lawyer advises doing so, is that polygraph results are generally inadmissible in court. See, e.g., Tennard v. State, 802 S.W.2d 678, 683 (Tex. Crim. App. 1990) (Existence and result of polygraph test inadmissible). In other words: If you fail the test, government decision-makers will probably believe that you are guilty; but even if you pass, it is unlikely that a jury would ever get to hear the results. In that sense, it can be a lose-lose proposition for a person whom the government requests to take a polygraph test.
A third reason for declining a government polygraph test is that you can always take a private polygraph test arranged by your lawyer. Our firm routinely arranges for private polygraph exams for clients who have been requested to take government-sponsored polygraph exams. The results of a private polygraph test may be kept confidential in the lawyer’s file. The results could also give the lawyer some idea about how the client might perform on a government test, under the right conditions. Our sex crime defense firm in Houston often hires private polygraph examiners who have previously worked for police agencies. That allows us to confidently share good results with government decision-makers, as well as prepare the client for a government-sponsored polygraph test if the client elects to take one. However, if a client fails a private polygraph test for any reason — for example if the client gets nervous or suffers from test anxiety — our firm is under no obligation to share the results with anyone.