The current state of the law regarding lie detector tests is that they can be admissible in a trial at the federal level, and at the state level they can be admissible if both parties agree. But the reality is that they are rarely ever used during trials. The reason is that in order for a person accused of a crime to submit to a polygraph examination for use at trial the accused must be willing to waive their constitutional right to remain silent. At our firm, we rarely agree to let our clients speak to law enforcement unless we feel that it will someway benefit our client. So the reason that lie detectors rarely are at issue during a trial is because police can not force a person to do one.
On the other hand, a good criminal defense attorney knows that a lie detector can be used very effectively in the right case. When we have a client that has informed us that “the police got the wrong guy,” we typically will immediately offer a private lie detector to our client. We utilize various polygraphists to conduct lie detector tests upon our clients, but all must be either current or former law enforcement officers. This way if our clients pass the test we know that prosecutors will be much more inclined to trust the results. If our client passes the lie detector, we now have extremely persuasive evidence of our client’s innocence to take to the prosecutor and try to convince them to drop the charges.
Consider this example of the persuasive power of a lie detector test. We recently had a 60-year old client, with no prior arrests in his entire life, who was faced with a 15-year minimum mandatory prison sentence for a drug trafficking charge. He insisted that he did not know that the drugs were hidden in the car that he was driving. We tried to convince the prosecutor of his innocence, but the prosecutor would not budge and stuck to his offer of 15 years prison or trial. So knowing that a jury can very easily convict a completely innocent man, we decided to polygraph our guy. He agreed without hesitation and he passed! We took the results to the prosecutor and 5 days later our client was released from jail and all charges against him were dropped.