Can a Polygraph be Used Against Me in Court?
You might wonder why every witness or criminal defendant is not strapped to a polygraph and tested to see if they are telling the truth. After all, you see the devices used in the movies and it seems to be accurate. However, the polygraph is not always admissible.
In fact, in most jurisdictions, a polygraph is nothing more than a show because it cannot be used in court. While they are referred to as “lie detectors,” these devices are not reliable when it comes to telling if a person is telling the truth. All they do is measure processes in the body to see if a person has reached a certain level of uncertainty, including heart rate and blood pressure. When a person is lying, these devices will determine such by the heightened heart rate and blood pressure.
The Unreliability of the Polygraph
While these devices can detect changes, they really are not detecting if you are telling the truth or not. There are dozens of other factors that can increase your heart rate and make you look as though you are lying when you are not – such as being a person with high blood pressure, being nervous, and more.
Some officers are even trained to increase your nervousness so that the machine registers that you are lying. These types of interrogation techniques can lead to false positives that can completely destroy a person’s life – further proving how unreliable the device can be.
With so many studies proving their unreliability – even if you take a polygraph – you likely will not have to worry about your results showing up in a court of law. These devices are heavily challenged by criminal defense attorneys based on their unpredictability, and in most cases judges do not allow them to be admitted into evidence.
Can You be Forced to Take One?
No state allows law enforcement to force a criminal defendant or person of interest to take a polygraph. However, most defendants are unaware of this right, and they may volunteer or accept the request out of fear that denying one would make them look guilty.
While refusing a test might make law enforcement assume that you are guilty, and result in their continued efforts to harass you by trying to get you to confess – remember that you are not required to take this test.
Can You Volunteer?
Yes, you can volunteer to take a polygraph test. And if you do agree to take a test, the results are typically not admissible in court. So regardless of the results, in most states you cannot use them in your defense, and the prosecution cannot use them against you.
The Catch of New Mexico Law
While most states do not allow these types of results to be entered, New Mexico is one of the few states that can and will use your polygraph results against you. How they will be weighed, however, is a different story.
So in New Mexico – we see a different picture than in most of the country. Polygraph results are admissible. So depending on the results, you can use them in your defense or the prosecution can use them to try to put you in jail. However, because the opposition will certainly (and easily) show the jury how unreliable the device is, the use of the results can end in a stalemate. If the jury believes the test is unreliable, the results may not factor into their decision much…or at all.
It is Best to Consult with a Defense Attorney
If you have been arrested, do not consent to a polygraph. Because the New Mexico law allows these devices to be used against you, it is best that you speak with an attorney first to explore your options and protect your rights.