According to the American Polygraph Association (APA), the polygraph is up to 87% accurate at detecting deception in examinees. Polygraph software developers claim their products are up to 97% accurate. So, why are lie detector results not admissible as evidence in court?

This post looks into the aspect of circumstantial evidence as it relates to the lie detector results. We’ll examine court rulings and case studies to give you the history of how the American Justice System views the relevancy of polygraph results.


Understanding the Federal Rules of Evidence

Let’s start by unpacking the admissibility of polygraph results per the Federal Rules of Evidence. According to the courts, lie detector results are admissible evidence, provided they meet the “Daubert standard.” The Federal Judge makes the decision on whether the lie detector results match up to these criteria since they act as a gatekeeper of admissibility regarding the Federal Rules of Evidence.

The introduction of polygraph software dramatically increased the accuracy of lie detector results. Studies published in peer-reviewed journals show the results of these advances. They argue that they meet the criteria of the Daubert standard, opening the move for renewed review of the inadmissibility rules.

Since 2009, 18 states have adopted the Daubert standard of polygraph results admissibility, with the judicial door swung open for others to follow. Federal and most state courts using the Frye standard have since denied the admissibility of polygraph results as evidence in court, with the exception of New Mexico.

19 States admit results of polygraph exams under stipulation by the prosecution and defense involved in the case. New Mexico permits the use of lie detector results without stipulations but under strict rules or evidence.


Daubert & The Supreme Court

In 1993, 70 years after the District of Columbia court ruled on the Frye standard, the US Supreme Court revisited it. The case of Daubert v. Merrell Dow Pharmaceuticals, Inc. saw the issuance of another milestone decision affecting expert testimony and its admissibility, which includes polygraph exam results.

Under the specific standard of the US Supreme Court in Daubert, the court’s ruling antiquated the Frye “general acceptance” standard with the following.

According to Rule 104(a), the judge must undertake a pre-trial assessment of the scientific viability of the testimony and its underlying methodology or reasoning. The results must be applicable to the facts involved in the case.

Considerations involved in this decision are whether the technique in question has been and can be tested. The method must be subject to a peer review and its publication, its potential or known error rate, and the maintenance and existence of standards of operation. The methodology must also have wide acceptance within the scientific community.

The ruling also states the cross-examination of evidence, presentation of contrary evidence, and instruction on the burden of proof, are appropriate rather than uncompromising “general acceptance” standards.

“General acceptance” is not a required precondition to the admissibility of testimony or polygraph results under the Federal Rules of Evidence. Rather the Rules of Evidence, namely Rule 702, assigns the judge the responsibility of ensuring expert testimony is reliable and relevant to the case. Pertinent evidence based on valid scientific principles satisfies these demands.


Examiner Validation

So, attorneys must ensure the polygraph examiner hired to conduct the lie detector test has formal training in polygraph techniques validated by published peer-reviewed scientific research.

This validation requires a minimum of two independent peer-reviewed studies published in journals. The court prefers the use of field studies over lab studies because lab studies are not transferrable to real-world situations.


The Admissibility of Psychophysiological Veracity Examinations

Psychophysiological Veracity Exams using the lie detector are available for use in civil and criminal cases involving Motions to Suppress Evidence, Plea Bargaining, Settlements, Supporting Evidence, Sentencing, Arbitration, Parole and Probation, and other Civil Actions.

Since the Daubert decision, judges have been more willing to accept polygraph results into evidence without a jury, especially during pre-trial and post-trial hearings.

The defense lawyer intending to introduce polygraph exam results as evidence in court on behalf of their client must understand the supersedence of the Frye standard to the Federal Rules of Evidence set by Daubert v. Merrill Dow Pharmaceuticals. Inc., which is only an invitation for forensic psychophysiology to demonstrate its worthiness of acceptance in court.

Therefore the attorney presenting to the court must introduce a well-prepared and competent polygraph examiner with formal training in certified and validated polygraph techniques. The testimony of a foundational expert must precede the examiner’s expert testimony, and a qualified and experienced quality control reviewer must confirm polygraph results.


Case Citations Involving the Introduction of Polygraph Results into Evidence


  • US v. Piccinonna 885 F.2d 1529 (11th Cir. 1989). Also note US vs. Henderson (11th Cir. 2005) 409 F.3d 1293, 1303.
  • US vs. Posado (5th Cir. 1995) WL 368417 (admission at the suppression pre-trial hearing).
  • US vs. William Galbreth, 908 F. Supp. 877, 64 USLW 2260, 43 Fed. R. Evid. Serv 585, 4 Oct 1995.
  • US vs. Richard Ridling, 350 F. Supp. 90 (E.D. Mich 1972)
  • US vs. David Crumby, 895 Fed Supp 1354 (DC AR. 1995).
  • US vs. Lee, 315 F.3d 206 (3d Cir. 2003). Polygraph exam results are permitted as a condition of supervised release at the discretion of the defendant’s probation officer.
  • US vs. Locke, 482 F.3d 764 (5th Cir. 2007). Polygraph exams as a condition of probation in a child pornography case.
  • US vs. Stoterau, 524 F.3d 988, 1003 (9th Cir. 2008). Polygraph examination as a condition of parole doesn’t infringe on the defendant’s Fifth Amendment rights. Defendants retain their 5th Amendment rights during the polygraph exam.
  • Ohio vs. Sahil Sharma. CR 06-09-3248 (2009). Polygraph results admitted over objections with refusal to overturn the ruling.
  • People vs. Wilkinson (122 Cal. Rprt.2d 703). The California Appeals court ruled that expert polygraph foundation testimony must be permitted in criminal trials.
  • Ohio vs. Sims, 52 Ohio Misc. 31; 369 N.E. 2d 24; (1977).
  • State vs. Valdez, 371 P.2d 894 (Arizona, 1962).
  • State vs. Dorsey, 539 P.2d 204 (New Mexico, 1975).
  • People vs. Kenney, 3 N.Y.S.2d 348, 167 Misc. 51 (Queens County Ct. 1938).
  • People vs. Daniels, 422 NYS2d. 832, 102 Misc 2d 540 (1979). Polygraph results admitted over objections.
  • People vs. Glenn Battle, Justice Lewis Douglass, NYS Supreme Court. Polygraph results admitted over objections.
  • People vs. Vernon, 391 NYS 2d 959 (1977).
  • Patterson vs. State, 633 S. W. 2d 549 (Tex.Cr.App. 1982).
  • Kumbo Tire Company, Ltd, et al. vs. Patrick Carmichael, 526 US 137 (1999). The court added that the Federal judge has the “gatekeeping” role under Rule 702, which extends to expert testimony, including soft science experts. They are subject to pre-trial Daubert issues similar to data-based science.
  • William Davis vs. The People of the State of New York: County of Erie Office of Children and Family Services Administrative Law Judge Proceeding.
  • US vs. Edward G. Scheffer, 41 MJ 683 (AF Ct. Crim App 1995) and 423 US 303 (1998) upheld the presidential ban on polygraph exam results in inadmissibility in military courts. However, there is room to challenge this ruling in that it permits States to ban polygraph exam results from evidence by statute due to the uncertain validity of results which is since been rectified by scientific studies published in peer-reviewed journals.
  • Furthermore, polygraph test results may be admitted in court as character evidence as per US vs. Crumby (d. Ar. 1995) 895 F. Supp. 1354, wherein the defendant’s mental health was avoided (US. vs. Campos, 217 F.3d 707 (9th Cir. 2000).
  • Jeffrey Bellin 80 Temp. L. Rev. 711, 726-727 (2007)


Polygraph Evidence and the Prohibition of Rule 704

Courts also ruled that expert scientific testimony regarding lie detector results is inadmissible under the Federal Rule of Evidence 704(b) due to deposition encompassing the “ultimate issue.” As outlined below, this objection has a narrow scope, even if it’s valid, and consequently shouldn’t provide a significant obstacle to the future admission of polygraph evidence.

The Federal Rule of Evidence 704 was originally drafted with the intention of abolishing common law doctrines prohibiting testimony on the “ultimate issue.” This prohibition deemed by the rules drafters to be difficult or application, unduly restrictive, and serving to deprive the introduction of useful information.”

In 1984, a mentally ill individual attempted assassination on President Ronal Reagan, and Congress passed the Insanity Defense Reform Act of 1984. This ruling added a subsection to Rule 704 to limit psychiatric testimony on behalf of defendants using the insanity defense.

The subsection of Rule 704 says that no expert witness who testifies with respect to a defendant’s mental state in criminal cases may state their opinion or inference as to the defendant’s mental state constituting a component of the crime they’re charged with or of the defense to it.

Despite contrarian arguments, many circuits interpreted Rule 704(b) as extending beyond the testimony of mental health professionals or psychiatric “to all expert witnesses.” The Ninth Circuit used two cases to subsequently apply this prohibition where polygraph experts were going to testify with an absence of criminal intent in the defendant’s answers during the polygraph exam.

Even if we assume Rule 704(b) applies to all expert testimony, proponents of polygraph expert testimony will have minimal challenges involved in avoiding its prohibition for several reasons.

Most polygraph evidence doesn’t pertain to the “mental health or condition” of the defendant. Consequently, it won’t trigger Rule 704(b). Instead, polygraph evidence establishes the credibility of objective factual statements.

Where a trial dispute involves an issue of intent, such as whether a murder was committed in self-defense or premeditated, polygraph evidence may be introduced without a direct inquiry into the defendant’s mental health or condition.

A defendant can disprove their intent circumstantially, in the same manner as the prosecutor would. Questioning presented from the polygraph exam must concern objective facts. However, these facts are offered to disprove criminal intent in this case.

For instance, if the defense wants to prove the defendant murdered someone in self-defense, there’s no need for expert testimony to inquire about the defendant’s intent directly. Instead, the expert can ask if the victim possessed a weapon, if they threatened to kill the defendant, and which party struck the first blow.

By proving the absence of the defendant’s criminal intent through circumstantial evidence provided by objective facts, expert testimony avoids conflicting with Rule 704(b).

Contrary to the analysis by the Ninth Circuit, a polygraph examiner can testify to the integrity of the defendant’s answer of their intent without violating the ultimate issue prohibition of Rule 704(b). This is because there’s a distinction between the defendant’s expert opinion, truthfully stating they acted with a specific intent (self-defense), and the perhaps prohibited opinion of the expert that the defendant acted with that intent.

Since the Ninth Circuit explained the prohibition in Rule 704(b) in another context, it doesn’t bar testimony supporting a conclusion or inference that the defendant does or doesn’t possess the requisite mental state as long as the expert doesn’t draw the ultimate decision or deduction for the jury and the ultimate conclusion or inference doesn’t necessarily follow on from their testimony.

Even the most advanced polygraph technology cannot enable experts to testify to the defendant’s prior intent. Rather, the most an expert can say is that the polygraph results indicated the defendant was truthful when voicing an innocent intent.

The ultimate issue regarding the defendant’s intent doesn’t necessarily follow from the testimony. Instead, as the prosecution will argue, the exam methodology or results might be flawed. Or the defendant may have deceived the test or deluded themselves. As a result, even if the testimony provided by the expert regarding the polygraph exam results is credited, the jury might conclude the defendant possessed a requisite criminal intent.

So, the excessively narrow importance of Rule 704(b) in the context of the polygraph exam results is, at best, that a polygraph examiner isn’t permitted to directly testify as to the integrity of the defendant’s response to questions like “can you explain your intent?” As discussed previously, even the exclusion of this testimony is legally questionable under the rule.


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