Polygraph Laws Regarding Admissibility

Myth: Polygraph results are never admissible in court.

This very common misconception can be dispelled with some helpful context.

We’ve provided a brief federal case history with explanations of how each case has affected the basic stance of the federal courts regarding polygraph tests in court. Let’s explore how polygraph laws have evolved as we answer the question: Are lie detector tests admissible in court?

Before we dive into the case law, I invite you to contact me now if you’re considering polygraph services. We can talk about your specific circumstances, and I’ll be transparent about the likelihood of a lie detection examination being beneficial to you.

1980 – United States v. Roberts

The thrust of this case was whether or not the grand jury prosecutor had deprived the defendant of due process. Specifically, it had been promised to the judge by the prosecutor that all the evidence given her had been shown to all members of the grand jury.

Turns out, that is not what happened. Among other pieces of evidence left out were the results of a polygraph test. The prosecutor had told the grand jury unequivocally that, according to the laws, polygraph results were inadmissible, and the court called her on the carpet and stated that it was false. Here is an excerpt from the case:

“The Court also disapproves of the prosecutor’s bold statement to the Grand Jury that polygraph evidence is inadmissible at trial. Such statements are untrue. The Ninth Circuit has held that polygraph evidence is admissible within the trial court’s discretion.”

1993 – Daubert vs. Merrell Dow Pharmaceuticals

This case was not about polygraph tests in court, but it did something very important that affected polygraph and lie detection laws.

It loosened the rules of evidence from the ‘general acceptance’ Frye ruling in 1923 and stated that ‘general acceptance’ was NOT a necessary pre-condition to the admissibility of scientific evidence.

Instead, the Daubert decision placed the decision-making power in the trial judge’s hands to “ensure that an expert’s testimony both rests on a reliable foundation and is relevant to the task at hand.”

Daubert also laid out factors, not a cut-and-dry list, but important factors to consider when determining the reliability of expert testimony. Those factors that led to loosening laws around polygraphs are:

• Whether the theories and techniques employed by the scientific expert have been tested
• Whether they have been subjected to peer review and publication
• Whether the techniques employed by the expert have a known error rate
• Whether they are subject to standards governing their application
• Whether the theories and techniques employed by the expert enjoy widespread acceptance

Starting with Daubert, anyone now had the right to request a motion for a hearing on the admissibility of lie detector tests in court as expert evidence. It didn’t mean that they would automatically be allowed, but the avenue by which a request could be made was now open. This was significant for the laws around polygraph usage.

1995 – United States v. Posado

This was a very important case for polygraph & lie detection. In the initial trial, the request for a ‘Daubert Hearing’ on polygraph & lie detection evidence at a pre-trial suppression hearing was denied, and the defendants were ultimately convicted.

The appeal rested primarily on the fact that, based on the specific details of this case, the court should have granted the Daubert hearing. The appeal was successful, and the defendants’ convictions were vacated.

1995 – United States v. Galbreth

As per the new laws around polygraphs, this case had a motion submitted for a Daubert hearing for the admissibility of polygraph evidence. The Daubert hearing was conducted, and the court found:

“Wherefore, it is ordered that Defendant’s Motion to Admit Expert Opinion Evidence Regarding Polygraph Results be and hereby is GRANTED.

The defendant was acquitted at trial prior to polygraph evidence being admitted to the jury. It was nonetheless a victory for polygraph tests in court.

1998 – United States v. Duque

The laws around polygraphs work both ways. Here, the defendant made a motion to submit polygraph evidence, and the state submitted a motion to exclude it. The court’s decision was in favor of the state, and the evidence was not admitted because the polygraph expert was found to be competent to testify about the scientific reliability of the control-question method of polygraph.

In other words, at least part of the reason is that the polygraph examiner was not prepared to defend the technique he was using. Secondly, the court stated that even if the defendant had developed a necessary foundation for the reliability of the polygraph, according to the laws, the polygraph evidence would be of small significance to the overall facts in the case, and that introducing it could prejudice the jury unnecessarily.

Basically, the way this case was handled by the defense is what hurt the polygraph test’s chances in court. The extra comments made by the court as their opinions have been misquoted extensively by opponents of polygraph as facts that polygraph is unreliable.

The full story is that the defense did a terrible job and the government did a great job, so much so that the court agreed with several of the premises set forth in opposition to the polygraph. When it comes to polygraph laws, this was ironic since the federal government did then and continues to utilize polygraph in other venues of defense and national security.

1998 – United States vs. Sheffer

One last bit about the history of polygraph tests is this: A complex and confusing case that revolved around a polygraph, but was equally a matter of the rules of evidence.

The only clear outcome of the case was that refusal to consider polygraph evidence in a court-martial was deemed not a violation of the defendant’s rights and that under Military Rule of Evidence 707, polygraph remains inadmissible in court-martial proceedings.

The effect this had on the overall admissibility of polygraph is varied and open to interpretation. It seems to somewhat undermine the polygraph laws in the Daubert decision, and at the same time, leaves individual state and local courts the freedom to decide on their own whether they want to consider admitting polygraph evidence.

A few general conclusions can be made from the years of polygraph and lie detection case law:

1. The court system is clearly at odds with itself over making any permanent, final decisions regarding the use of polygraph and lie detector tests in court.
2. Ultimately, it is up to the trial judge as to how he or she will handle any motion to admit polygraph evidence.
3. When it comes to the law, a polygraph is regularly admitted as evidence in a trial.
4. Polygraph is also regularly rejected as evidence in a trial.
5. Polygraph is widely used and accepted daily in other venues of government, such as pre-employment testing, testing for security clearances, and tests for espionage and sabotage. And these areas have been growing, not slowing.

The Court’s View on Polygraph Credibility

So, can a polygraph be used in court? Yes and no. But here is what’s most important to remember: Even when polygraph test results in court are not admitted as direct evidence, they may still play a behind-the-scenes role in shaping cases.

Prosecutors and defense attorneys alike may use results to inform plea negotiations and pre-trial strategies, investigate priorities, for judicial discretion, and more.

The bottom line is that while polygraph laws might change from time to time, polygraph tests can and do influence court outcomes, even when they don’t make it into the record. This is why, if you are going to have such a test done, you need a qualified examiner and defensible testing protocols, especially when credibility and expert reliability are under the microscope. Lucky for you, if you are in NC, SC, or GA, I can help you with that. Schedule your free, confidential consultation with me today.