This appeal concerns the admissibility of polygraph evidence in a pretrial hearing to suppress forty-four kilograms of cocaine recovered after an airport interdiction and search of the defendants’ luggage. The district court refused to consider polygraph evidence offered by the defendants to corroborate their version of events preceding the arrest. Our precedent, with few variations, has unequivocally held that polygraph evidence is inadmissible in a federal court for any purpose.
See, Barrel of Fun, Inc. v. State Farm Fire & Cas. Co.,
BACKGROUND
Defendants Miriam Henao Posado, Pablo Ramirez and Irma Clemencio Hurtado were each indicted and subsequently convicted of one count of conspiracy to possess and one count of possession with intent to distribute in excess of five kilograms of cocaine in violation of 21 U.S.C. §§ 841(a)(1), 841(b)(a)(A) and 846. Prior to trial the defendants moved to suppress the cocaine found in their luggage and certain post-arrest statements. At issue was whether the defendants validly consented to a search of their luggage. The prosecution sought to justify the search solely on the basis of consent, offering a Spanish-language consent form executed by all three defendants. 1 The three defendants, by way of affidavit, claimed (1) that they were not asked to consent and did not consent, either orally or in writing, to the search of their luggage until after the bags had been opened, (2) that they were told they were under arrest before their bags were searched, and (3) that they were not given Miranda warnings before the bags were opened. Defendants contended that the consent was invalid either (1) because it was given after the bags were opened, or (2) because it followed and was tainted by an illegal arrest without probable cause.
Events Leading up to the Search
On September 17, 1993, Miriam Henao Posado, Pablo Ramirez and Irma Clemencio Hurtado arrived at Houston Intercontinental Airport in a maroon car driven by an unidentified third party. As they unloaded their *430 baggage, they were observed by Houston Police Department (HPD) Officers Rodriguez and Furstenfeld and an agent with the Drug Enforcement Agency (DEA). The officers became suspicious that the defendants might be carrying narcotics based on certain characteristics of the defendants’ baggage and behavior. Based on those suspicions and prior to confronting the defendants, the officers retrieved from the airline the three suitcases checked by the defendants and “prepped” one of the bags. “Prepping” involves squeezing the sides of a bag, which causes the odor of whatever is contained inside to be emitted. In this case, the officers detected fabric softener, which is often used by narcotics traffickers to mask the odor of narcotics in transport.
Shortly thereafter, the two HPD officers approached the defendants in the snack bar area, identified themselves as police officers and asked the defendants for their tickets and identification. When it became apparent that none of the defendants spoke English, Officer Rodriguez conversed with them in Spanish. Neither Posado nor Hurtado were carrying any identification, and the name on the identification produced by Ramirez did not match either his ticket or the name placed on the baggage tag. Ramirez’ identification was examined and then returned to him.
When asked about luggage, the defendants responded by indicating three carry-on bags. When Officer Rodriguez pointed to the baggage tags stapled inside the defendants’ ticket folders, one of the defendants conceded that they had checked three suitcases. Here the stories diverge. Officer Rodriguez testified that, after expressing some concern about missing their flight, the defendants agreed to accompany him downstairs so that he could inspect the luggage. He also testified that he advised the defendants at that time that they were free to leave. The defendants testified that Officer Rodriguez never informed them that they were free to leave and that they were under the impression that they were not free to leave.
See Florida v. Bostick,
The officers testified that immediately after asking for keys, Officer Rodriguez secured the defendants’ consent to search, both orally and in writing. Officer Rodriguez also testified that he advised the defendants in Spanish that they were not required to consent. Next, Officer Furstenfeld unsuccessfully attempted to open the suitcases using a master set of luggage keys. Only then, according to the officers, were the padlocks pried open and the bags searched.
The defendants testified that immediately after they were asked for keys, Officer Fur-stenfeld began trying to open the suitcases with the master set of keys. When he could not, Officer Furstenfeld pried open the padlock and opened the zipper slightly. At that point, the defendants claim, Officer Fursten-feld stopped suddenly and ran upstairs. In his absence, the DEA agent continued opening the suitcase with a pen knife, looked inside and announced that it contained drugs. At that point, the defendants testified, Officer Furstenfeld returned with the consent form and it was executed by the defendants. Afterwards, the other two suitcases were opened.
The Polygraph Examinations
Perceiving that the suppression hearing would amount to a “swearing match” between the three officers and the three defendants (that the defendants would be likely to lose), the defendants arranged to submit to polygraphs to establish the truth of the assertions in their affidavits. Well before the tests were given, counsel for the defendants *431 contacted the prosecution and extended the opportunity to participate in the tests. The defendants also offered to stipulate that the results would be admissible in any way the government wanted to use them, at trial or otherwise. The prosecution declined this opportunity.
Subsequently, the defendants were examined by polygraph experts Paul K. Minor and Ernie Hulsey. In separate examinations each defendant was asked the following questions and each gave the following answers:
A. Before opening that first bag, did any police official ever ask for permission to search any of those bags? No.
B. Before searching your luggage, were you told that you were under arrest? Yes.
C. At the airport, were you ever told that you were free to leave? No.
D. Did you deliberately lie in your affidavit? No.
E. Before opening your bags, did the police officials advise you of your Miranda rights? No.
Both Minor and Hulsey concluded that in each case “deception was not indicated.” Thereafter, the defendants moved for an order allowing Minor and Hulsey to testify regarding the results of the three tests at the pretrial suppression hearing or, in the alternative, for a hearing on the admissibility of polygraph results as expert evidence under the Federal Rules of Evidence and the standards enunciated by the Supreme Court in
Daubert v. Merrell Dow Pharmaceuticals,
— U.S. -,
At the beginning of the subsequent suppression hearing, the district court summarily refused to consider the polygraph testimony and also refused to consider whether the testimony was rehable and relevant under the Federal Rules of Evidence, stating:
I am a great believer in polygraph, that polygraph technique, I think it’s extremely effective as a law enforcement tool. I do not believe, however, that it belongs in the courtroom, either before the Court or before the jury, for several reasons, one of which is that it will lead to an impossible situation where we will have to hear polygraph experts on both sides, and we’ll get into the same battle of experts that we get into in so many areas of the law.
I am very concerned that it does have some valid use in determining whether people are likely to be truthful or likely not to be truthful, however, I think it opens up some policy questions that belong either to Congress or to the appellate courts to resolve before we get into it here in the courtroom.
At the conclusion of the suppression hearing, the district court denied the defendants’ motion to suppress, holding that the defendants knowingly and voluntarily consented to a search of their luggage before any of the bags were opened, and that the defendants were not arrested until after the bags were searched. Shortly after the hearing, the defendants and the government entered into a stipulation that the defendants would be tried by the court on the evidence presented at the suppression hearing. All three defendants were convicted on both the conspiracy to possess and possession counts, and this appeal followed.
APPLICABLE LAW
On appeal, the defendants contend that
Daubert
required the district court to conduct a hearing on the admissibility of the polygraph evidence as expert testimony under Federal Rule of Evidence 702. Defendants also argue that the district court erred in refusing to consider polygraph evidence where it was offered solely for use in a pretrial suppression hearing, relying on
Bennett v. City of Grand Prairie, Texas,
We reject the defendants’ argument that
Bennett
controls.
Bennett
held that it was not error for a magistrate to consider an affidavit referring to polygraph results, along with other evidence, to determine whether there was probable cause to issue an arrest warrant.
We also reject the government’s invitation to short-circuit the Daubert analysis by finding that the district court implicitly relied on Rule 403 to exclude the evidence. We conclude that the district court applied a per se rule against admitting polygraph evidence. Even the government concedes that that rule is no longer viable after Daubert. Therefore, the case must be remanded.
From Frye to Daubert — Rule 702
Before
Daubert,
the standard for determining the admissibility of scientific or technical evidence in our circuit was the
Frye
“general acceptance” test, which required the proponent to demonstrate that the science or technology relied upon enjoyed general acceptance in the relevant scientific or technical field from which it arose. The
Frye
test originated in a short and citation-free case in which a criminal defendant attempted to introduce what
Daubert
called a “crude predecessor” of the polygraph to demonstrate his innocence in a murder trial.
Daubert,
— U.S. at -,
Daubert
expressly rejected the “austere”
Frye
standard, holding that the
Frye
approach was superseded by adoption of the Federal Rules of Evidence. — U.S. at -,
Whether evidence assists the trier of fact is essentially a relevance inquiry.
*433
Daubert,
— U.S. at -,
Evidentiary reliability, or trustworthiness, is demonstrated by a showing that the knowledge offered is “more than speculative belief or unsupported speculation.”
Daubert,
— U.S. at -,
What remains is the issue of whether polygraph technique can be said to have made sufficient technological advance in the seventy years since Frye to constitute the type of “scientific, technical, or other specialized knowledge” envisioned by Rule 702 and Daubert. We cannot say without a fully developed record that it has not.
Even before
Daubert,
this court’s view of polygraph evidence had expanded somewhat.
See Bennett,
*434
There can be no doubt that tremendous advances have been made in polygraph instrumentation and technique in the years since
Frye.
The test at issue in
Frye
measured only changes in the subject’s systolic blood pressure in response to test questions.
Frye v. United States,
To iterate, we do not now hold that polygraph examinations are scientifically valid or that they will always assist the trier of fact, in this or any other individual case. We merely remove the obstacle of the per se rule against admissibility, which was based on antiquated concepts about the technical ability of the polygraph and legal precepts that have been expressly overruled by the Supreme Court.
*435 Rule 403 as Gatekeeper
Assuming that polygraph evidence satisfies the requirements of Rule 702 does not end the inquiry. Other evidentiary rules, such as Rule 408, may still operate to exclude the evidence.
Daubert,
— U.S. at -,
Aside from
Frye,
the traditional objection to polygraph evidence is that the testimony will have an unusually prejudicial effect which is not justified by its probative value, precisely the inquiry required of the district court by Rule 403.
See Bennett,
We note also that there are factors in this record which substantially boost the probative value of this evidence. The evidence at the suppression hearing essentially required the district court to decide between the story told by the officers and that told by the defendants, not an unusual situation, and perhaps not sufficient alone to justify admission of “tie-breaker” evidence carrying a high potential for prejudicial effect. In this ease, however, there was more. Because Officer Rodriguez was the only Spanish-speaking officer on the scene, he alone could testify as to what the defendants were told and as to their understanding of whether they were under arrest or whether they were consenting to a search of their baggage. Although Officer Rodriguez testified that he explained the consent form to the defendants, he was unable to read the consent form (printed in Spanish) to the court at both the probable cause hearing and the suppression hearing. There was also evidence calling the officers’ recollection of events into question. For example, Officer Rodriguez testified incorrectly at the probable cause hearing that the defendants were travelling with one-way tickets, a fact which he said contributed to his reasonable suspicion that the defendants were carrying drugs. The defendants were in fact holding round-trip tickets. In addition, the defendants offered the testimony of a disinterested witness, an airline employee, who contradicted the officers’ version of the events surrounding their retrieval of the defendants’ bags from the airline prior to the search. Finally, the defendants introduced at the suppression hearing an order from a similar case in another district court in the Southern District involving Officer Rodriguez. In that case, the district court judge found that Officer Rodriguez’ version of the events leading up to the search in that case was “untruthful” and therefore suppressed evidence obtained after the defendants allegedly consented to the search. Taken individually, each one of these inconsistencies can be explained and may seem inconsequential. Taken together, however, we believe that they can be said to enhance the need for evidence, and therefore its probative value, for clarify *436 ing which of the competing versions of what happened that day is true.
CONCLUSION
The district court essentially applied the per se rule against admitting polygraph evidence established by our earlier precedent. Because the district court’s assessment of the proffered polygraph evidence under the Dau-bert standard may well affect the other issues raised by this appeal, it is inappropriate at this time to address the district court’s decision to exclude the polygraph evidence from its consideration on the motion to suppress or its fact finding that the search was supported by valid consent. Those issues can be adequately addressed on subsequent appeal, if necessary.
It is with a high degree of caution that we have today opened the door to the possibility of polygraph evidence in certain circumstances. We may indeed be opening a legal Pandora’s box. However, that the task is full of uncertainty and risk does not excuse us from our mandate to follow the Supreme Court’s lead. Rather, “[m]indful of our position in the hierarchy of the federal judiciary, we take a deep breath and proceed with this heady task.”
Daubert v. Merrell Dow Pharmaceuticals, Inc.,
Nor are we unaware that our opinion today may raise as many questions as it answers. We leave much unsaid precisely because we believe that the wisdom and experience of our federal district judges will be required to fashion the principles that will ultimately control the admissibility of polygraph evidence under Daubert.
For the foregoing reasons, the district court’s ruling on the motion to suppress is REVERSED, the defendants’ convictions are VACATED and the case is REMANDED to the district court for consideration of the evidentiary reliability and relevance of the polygraph evidence proffered by the defendants under the principles embodied in the Federal Rules of Evidence and the Supreme Court’s decision in Daubert.
Notes
. As counsel for the government stated in oral argument, this case was treated "only as a consent case.” It would be inappropriate, on the basis of the present record, to determine whether independent probable cause existed for the search. We note, however, that that issue may well be appropriate for consideration on remand.
. Rule 702 governing expert testimony provides: If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
. Rule 104(a) provides:
"Preliminary questions concerning the qualification of a person to be a witness, the existence of a privilege, or the admissibility of evidence shall be determined by the court, subject to the provisions (b) [pertaining to conditional admissions]. In making its determination it is not bound by the rules of evidence except those with respect to privileges.”
. The example given by the Supreme Court demonstrates that particular evidence may have validity for some purposes and not for others:
The study of the phases of the moon, for example, may provide valid scientific “knowledge” about whether a certain night was dark, and if darkness is a fact in issue, the knowledge will assist the trier of fact. However (absent credible grounds supporting such a link), evidence that the moon was full on a certain night will not assist the trier of fact in determining whether an individual was unusually likely to have behaved irrationally on that night.
- U.S. at -,
. Several other circuits went further by granting the district court limited discretion to consider polygraph evidence in certain circumstances.
E.g., United States v. Johnson,
. See 22 Charles A. Wright & Kenneth W. Graham, Federal Practice and Procedure § 5169 at 95 n. 7 (1978); Ronald J. Simon, Adopting a Military Approach to Polygraph Evidence Admissibility: Why Federal Evidentiary Protections Will Suffice, 25 Tex.Tech L.Rev. 1055, 1059 (1994).
.
Bennett,
.
See United States v. Piccinonna,
.
See Piccinonna,
. See 22 Charles A. Wright & Kenneth W. Graham, Federal Practice & Procedure § 5169 at 92 n. 2 (collecting an impressive bibliography).
