Opinion of the Court
GIERKE, Judge:A general court-martial composed of officer members at March Air Force Base, California, convicted appellant, contrary to his pleas, of uttering bad checks, wrongfully using methamphetamine, failing to go to his appointed place of duty, and absenting himself from his unit for 13 days without authority, in violation of Articles 123a, 112a, and 86, Uniform Code of Military Justice, 10 USC §§ 923a, 912a, and 886, respectively. The adjudged and approved sentence provides for a bad-conduct discharge, confinement for 30 months, total forfeitures, and reduction to the lowest enlisted grade. The Court of Criminal Appeals affirmed the findings and sentence but awarded one day of credit for lack of timely pretrial confinement review, relying on County of Riverside v. McLaughlin, 500 U.S. 44, 111 S.Ct. 1661, 114 L.Ed.2d 49 (1991), and United States v. Rexroat, 38 MJ 292 (CMA 1993). See 41 MJ 683, 693 (1995); see also RCM 305(k), Manual for Courts-Martial, United States (1995 ed.).
We granted review of the following issue:
WHETHER THE MILITARY JUDGE ERRED IN DENYING APPELLANT’S MOTION TO PRESENT EVIDENCE OF A FAVORABLE POLYGRAPH RESULT CONCERNING HIS DENIAL OF USE OF DRUGS WHILE IN THE AIR FORCE.
In March of 1992, appellant began working as an informant for the Air Force Office of Special Investigations (OSI). During late March and early April, appellant told OSI that two civilians, Davis and Fink, were dealing in significant quantities of drugs. On April 7,1992, at the request of OSI, appellant voluntarily provided a urine sample. Periodic urinalyses are normal procedure for controlled informants.
On April 10, OSI asked appellant to submit to a polygraph examination. The OSI polygraph examiner asked appellant three questions: (1) Had he ever used drugs while in the Air Force; (2) had he ever lied in any of the drug information he gave to OSI; and (3) had he told anyone other than his parents that he was assisting OSI? Appellant answered “No” to each question. The polygraph examiner concluded that “no deception” was indicated.
Appellant’s urinalysis tested positive for methamphetamine. The report was dated May 20, although local OSI agents may have learned of the results as early as May 14.
At trial appellant asked the military judge for an opportunity to lay a foundation for the favorable polygraph evidence. The military judge denied the request without receiving any evidence, ruling that “the President may, through the Rules of Evidence, determine that credibility is not an area in which a factfinder needs help, and the polygraph is not a process that has sufficient scientific acceptability to be relevant.” He further ruled that under Mil.R.Evid. 403, Manual for Courts-Martial, United States (1995 ed.),
[t]he factfinder might give it too much weight, and ... there is an inordinate amount of time and expense, especially in the cases where there may be conflicting tests, which doesn’t appear to be the case here. The main confusion of the issue; that is, the question of what the result of the polygraph was, as opposed to the question of whether or not the accused used drugs [is another problem].
During the trial on the merits, appellant testified that he visited Davis on April 6, left Davis’ house around midnight, and began *444driving toward March Air Force Base. The next thing he remembered was waking up the next morning in his car in a remote area, not knowing how he got there. He denied “knowingly” ingesting drugs at any time between March 5, when he began working for OSI, and April 7, the date he provided the .urine sample that tested positive for methamphetamine.
Trial counsel cross-examined appellant about inconsistencies between his trial testimony and earlier statements to the OSI and about his lack of a “sudden rush of energy” and other symptoms of ingesting methamphetamine. Trial counsel’s closing argument urged the court members to look at appellant’s credibility. Trial counsel argued, “He lies. He is a liar. He lies at every opportunity he gets and he has no credibility. Don’t believe him. He knowingly used methamphetamine, and he is guilty of Charge II.”
Appellant asserts that Mil.R.Evid. 707 violated his Sixth Amendment right to present a defense because it compelled the military judge to exclude relevant, material, and favorable evidence offered by appellant. He argues that he was constitutionally entitled to be given an opportunity to rebut the attack on his credibility as a witness by laying a foundation for favorable polygraph evidence. The Government asserts that the Rule does not impermissibly infringe on the Sixth Amendment. It argues that Mil. R.Evid. 707 merely codifies all the evidentiary prohibitions against polygraph evidence and that, even without Mil.R.Evid. 707, polygraph evidence would never be admissible. We agree with appellant.
In Frye v. United States, 293 F. 1013 (D.C.Cir.1923), polygraph evidence was held to be inadmissible because it was unreliable. In United States v. Gipson 24 MJ 246, 253 (CMA 1987), our Court held that an accused is “entitled to attempt to lay” the foundation for admission of favorable polygraph evidence.. In arriving at that holding, our Court acknowledged that Mil.R.Evid. 702 “may be broader and may supérsede Frye v. United States,” supra 24 MJ at 251. The impact of our Gipson decision was short-lived, however, because on June 27,1991, the President promulgated Mil.R.Evid. 707 in Executive Order No. 12767, § 2, 56 Fed.Reg. 30296.
MiLR.Evid. 707 provides: “Notwithstanding any other provision of law, the results of a polygraph examination, the opinion of a polygraph examiner, or any reference to an offer to take, failure to take, or taking of a polygraph examination, shall not be admitted into evidence.” Unlike most military rules of evidence, Mil.R.Evid. 707 has no counterpart in the Federal Rules of Evidence. It is similar to Cal.Evid.Code 351.1 (West 1988 Supp.). See People v. Kegler, 197 Cal.App.3d 72, 84, 242 Cal.Rptr. 897, 905 (1987). Mil.R.Evid. 707 “is not intended to accept or reject United States v. Gipson, 24 MJ 246 (CMA 1987), concerning the standard for admissibility of other scientific evidence under Mil.R.Evid. 702 or the continued vitality of Frye v. United States, 293 F. 1013 (D.C.Cir.1923).” Drafters’ Analysis of Mil.R.Evid. 707, Manual, supra (1995 ed.) at A22-48.
Presidential authority to promulgate rules of evidence is founded on Article 36(a), UCMJ, 10 USC § 836(a). That Article provides that such rules “shall, so far as [The President] considers practicable, apply the principles of law and the rules of evidence generally recognized in the trial of criminal cases in the United States district courts, but which may not be contrary to or inconsistent with this chapter.”
Appellant’s case presents two questions. The first is a statutory question: Did the President comply with Article 36 when he promulgated Mil.R.Evid. 707? The second is a constitutional question: Does Mil.R.Evid. 707 violate the Sixth Amendment? We review these questions of law de novo. United States v. Ayala, 43 MJ 296, 298 (1995).
The statutory question was neither briefed nor argued. It may well be that the per se prohibition in Mil.R.Evid. 707 is “at odds with the ‘liberal thrust’ of the Federal Rules and their ‘general approach of relaxing the traditional barriers to “opinion” testimony.’ ” Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 588, 113 S.Ct. 2786, 2794, 125 L.Ed.2d 469 (1993). We note that the majority of the federal circuits do not have a per se prohibition against polygraph evi*445dence. Instead, they rely on the trial judge to apply a Dauhert analysis and apply Fed. R.Evid. 401-03. United States v. Pulido, 69 F.3d 192, 205 (7th Cir.1995) (no per se rule against admissibility of polygraph evidence); see United States v. Posado, 57 F.3d 428, 436 (5th Cir.1995) (reversing per se exclusion of polygraph evidence); United States v. Piccinonna, 885 F.2d 1529, 1535 (11th Cir.1989) (holding that polygraph evidence not inadmissible per se); Anderson v. United States, 788 F.2d 517, 519 n. 1 (8th Cir.1986) (polygraph evidence admissible by stipulation); see also United States v. A & S Council Oil Co., 947 F.2d 1128, 1134 n. 4 (4th Cir.1991) (holding polygraph evidence not admissible in 4th Circuit but recognizing that “[cjircuits that have not yet permitted evidence of polygraph results for any purpose are now the decided minority”). But see United States v. Scarborough, 43 F.3d 1021, 1026 (6th Cir.1994) (polygraph results “inherently unreliable”); United States v. Soundingsides, 820 F.2d 1232, 1241 (10th Cir.1987) (polygraph evidence “not admissible to show” that witness “is truthful”); United States v. Skeens, 494 F.2d 1050, 1053 (D.C.Cir.1974) (adhering to Frye and holding polygraph evidence inadmissible); Dowd v. Calabrese, 585 F.Supp. 430 (D.D.C.1984) (polygraph results not sufficiently reliable to be admissible).
The Federal rules are virtually identical to Mil.R.Evid. 401-03. Whether the President determined that prevailing federal practice is not “practicable” for courts-martial cannot be determined from the record before us. Assuming without deciding that the President acted in accordance with Article 36 and determined that the prevailing federal rule is not “practicable” for courts-martial, we turn to the constitutional question.
Our Court entertained a direct attack on the constitutionality of Mil.R.Evid. 707 in United States v. Williams, 43 MJ 348 (1995). We held, however, “that the accused had no right to introduce the polygraph evidence without taking the stand and testifying consistently, or without offering some other plausible evidentiary basis.” 43 MJ at 355. See also United States v. Abeyta, 25 MJ 97, 98 (CMA 1987) (polygraph evidence not relevant unless accused testifies). In Williams we observed: “Thus, in the appropriate case, the question will be whether the proffered polygraph evidence is sufficiently reliable and necessary that its automatic exclusion violates the accused’s constitutional trial rights.” 43 MJ at 353.
Unlike Williams, this appellant testified, placed his credibility in issue, and was accused by the prosecution of being a liar. Thus the constitutional issue is squarely presented. We hold that Mil.R.Evid. 707, as applied to this case, is unconstitutional. A per se exclusion of polygraph evidence offered by an accused to rebut an attack on his credibility, without giving him an opportunity to lay a foundation under Mil.R.Evid. 702 and Daubert, violates his Sixth Amendment right to present a defense. We limit our holding to exculpatory evidence arising from a polygraph examination of an accused, offered to rebut an attack on his credibility. We leave for another day other constitutional questions such as those involving government-offered polygraph evidence or evidence of a polygraph examination of a witness other than an accused.
The Sixth Amendment grants an accused “the right to call “witnesses in his favor.’ ” Rock v. Arkansas, 483 U.S. 44, 52, 107 S.Ct. 2704, 2709, 97 L.Ed.2d 37 (1987). An accused’s right to present testimony that is relevant and material may not be denied arbitrarily. Washington v. Texas, 388 U.S. 14, 23, 87 S.Ct. 1920, 1925, 18 L.Ed.2d 1019 (1967); see United States v. Woolheater, 40 MJ 170, 173 (CMA 1994).
The right to present evidence, however, is not unlimited but “may, in appropriate cases, bow to accommodate other legitimate interests in the criminal trial process.” Chambers v. Mississippi 410 U.S. 284, 295, 93 S.Ct. 1038, 1046, 35 L.Ed.2d 297 (1973). See, e.g., Washington v. Texas, 388 U.S. at 23 n. 21, 87 S.Ct. at 1925 n. 21 (right to present testimony may be limited by testimonial privilege or rules relating to mental ability to testify). When restrictions are placed on an accused’s right to present evidence, they “may not be arbitrary or disproportionate to the purposes they are designed to serve.” *446Rock v. Arkansas, 483 U.S. at 56, 107 S.Ct. at 2711. Applying the foregoing principles, the Supreme Court held in Rock that a per se rule excluding the defendant’s hypnotically refreshed testimony infringed his right to present a defense. The Supreme Court held that a “legitimate interest in barring unreliable evidence does not extend to per se exclusions that may be reliable in an individual case.” 483 U.S. at 61, 107 S.Ct. at 2714. While Rock concerned exclusion of a defendant’s testimony and this case concerns exclusion of evidence supporting the truthfulness of a defendant’s testimony, we perceive no significant constitutional difference between the two. In either case, the Sixth Amendment right to present a defense is implicated.
Mil.R.Evid. 702 permits expert testimony when “scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue.” Expert testimony is subject to the relevance requirements of Mil. R.Evid. 401 and 402 and the balancing requirements of Mil.R.Evid. 403. In Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. at 597, 113 S.Ct. at 2798, the Supreme Court made the trial judge a gatekeeper, trusted with responsibility to decide if novel scientific evidence was sufficiently relevant and reliable to warrant admission.
An expert witness may not testify that a declarant was telling the truth but may testify to the absence of indicia of deception. Thus, in United States v. Cacy, 43 MJ 214, 218 (1995), we held that it was not error to permit an expert to testify that a victim’s accusation did not appear to be feigned or rehearsed. Similarly, in United States v. Suarez, 35 MJ 374, 376 (CMA 1992), we held that it was not error for an expert to opine that counter-intuitive conduct, such as recanting an accusation, inconsistent statements, or failing to report abuse is not necessarily inconsistent with a truthful accusation. See also United States v. Houser, 36 MJ 392, 398-400 (CMA 1993). Finally, we have permitted experts to opine whether a complainant “can differentiate between fantasy and fact.” United States v. Palmer, 33 MJ 7, 12 (CMA 1991); United States v. Tolppa, 25 MJ 352, 354-55 (CMA 1987), citing United States v. Azure, 801 F.2d 336, 340 (8th Cir.1986). Under the same rationale as these cases, a properly qualified expert, relying on a properly administered polygraph examination, may be able to opine that an accused’s physiological resppnses to certain questions did not indicate deception.
Polygraph examinations were relatively crude when Frye was decided. See Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. at 585, 113 S.Ct. at 2793. The Eleventh Circuit has recognized that, “[sjince the Frye decision, tremendous advances have been made in polygraph instrumentation and technique.” United States v. Piccinonna, 885 F.2d at 1532; see also United States v. Galbreth, 908 F.Supp. 877 (D.N.M.1995); United States v. Crumby, 895 F.Supp. 1354 (D.Ariz.1995). The effect of Mil.R. Evid. 707 is to freeze the law regarding polygraph examinations without regard for scientific advances. We believe that the truth-seeking function is best served by keeping the door open to scientific advances. See United States v. Youngberg, 43 MJ 379 (1995) (holding DNA evidence admissible); United States v. Nimmer, 43 MJ 252, 260 (1995) (remanding for hearing on reliability of hair analysis evidence). With respect to appellant’s ease, we, like the Fifth Circuit, cannot determine “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.” United States v. Posado, 57 F.3d at 433. We will never know, unless we give appellant an opportunity to lay the foundation.
Like the Court in Posado, “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.” 57 F.3d at 434. Foundation evidence for proffered polygraph evidence must establish that the underlying theory — that a deceptive answer will produce a measurable *447physiological response — is scientifically valid. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. at 592-93, 113 S.Ct. at 2796-97. Furthermore, we would expect evidence that the theory can be applied to appellant’s case. Id. The foundation must include evidence that the examiner is qualified, that the equipment worked properly and was properly used, and that the examiner used valid questioning techniques.
As required by Daubert, the military judge must be a gatekeeper and weigh probative value against prejudicial impact in accordance with MiLR.Evid. 403. We find the Piccinonna guidance apt:
[T]he trial court may exclude polygraph expert testimony because 1) the polygraph examiner’s qualifications are unacceptable; 2) the test procedure was unfairly prejudicial or the test was poorly administered; or 3) the questions were irrelevant or improper. The trial judge has wide discretion in this area, and rulings on admissibility will not be reversed unless a clear abuse of discretion is shown.
885 F.2d at 1537; see also United States v. Pettigrew, 77 F.3d 1500, 1514 (5th Cir. 1996) (judge’s ruling on admissibility of polygraph evidence reviewed for abuse of discretion).
This was not a private, ex parte examination under unknown conditions. See United States v. Sherlin, 67 F.3d 1208, 1217 (6th Cir.1995) (“unilaterally” obtained and “privately commissioned” polygraph excluded). To the contrary, appellant proffers a government-initiated examination by an OSI examiner. Accordingly, there would appear to be no need to condition admissibility on having appellant examined by a polygraph examiner chosen by the prosecution. See United States v. Piccinonna, 885 F.2d at 1536.
Finally, the issues raised by the dissenting opinion warrant comment. Both Wood v. Bartholomew, — U.S. —, 116 S.Ct. 7, 133 L.Ed.2d 1 (1995), and State v. Ellison, 36 Wash.App. 564, 676 P.2d 531, 535 (1984), involve polygraph examinations of prosecution witnesses, not the accused. Our holding, as was that in Rock, is limited to an accused’s right to lay the foundation for a polygraph examination of himself. We need not and do not address admissibility of polygraph examinations of government witnesses or the question whether such polygraph evidence would be constitutionally required to be disclosed under Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963). But cf. United States v. Simmons, 38 MJ 376 (CMA 1993) (trial counsel failed to discover and disclose contradictory statements of rape prosecutrix made to government polygrapher).
Furthermore, Bartholomew involves an issue different from the one in the case before us. It is summary disposition of a habeas corpus case, where the Supreme Court concluded that the Ninth Circuit misapplied the Court’s Brady jurisprudence. — U.S. at -, 116 S.Ct. at 8. The Supreme Court noted that polygraph evidence was inadmissible under Washington state law but premised its holding on the speculative nature of the additional evidence that might have been discovered, counsel’s concession “that disclosure would not have affected the scope of his cross-examination,” and the “overwhelming” evidence of guilt. — U.S. at-, 116 S.Ct. at 10-11. The constitutionality of the state law was not before the Court and therefore, consistent with the Court’s practice, it was not addressed. See United Public Workers of America v. Mitchell, 330 U.S. 75, 90 n. 22, 67 S.Ct. 556, 564 n. 22, 91 L.Ed. 754 (1947) (“It has long been this Court’s ‘considered practice not to decide abstract, hypothetical or contingent questions, ... or to decide any constitutional question in advance of the necessity for its decision, ... or to formulate a rule of constitutional law broader than is required by the precisé facts to which it is to be applied, ... or to decide any constitutional question except with reference to the particular facts to which it is to be applied.’ ”)
Montana v. Egelhoff, — U.S. —, 116 S.Ct. 2013, 135 L.Ed.2d 361 (1996), also involves a constitutional.issue different from the one before us. Egelhoff involves legislative action redefining an element of an offense, not executive rule-making about modes of proof. The President, unlike the Montana legislature, lacks authority to create and define offenses. See Art. 36(a), UCMJ, 10 USC § 836(a); United States v. Hemingway, 36 *448MJ 349, 351 (CMA 1993); United States v. Smith, 13 USCMA 105, 119, 32 CMR 105, 119 (1962).
In Egelhoff, the Supreme Court upheld a statute excluding evidence of voluntary intoxication when a defendant’s state of mind is at issue. The statute in question, Mont.Code Ann. § 45-2-203, provided that voluntary intoxication “may not be taken into consideration in determining the existence of a mental state which is an element of [a criminal] offense.” — U.S. at-, 116 S.Ct. at 2016. The Supreme Court’s decision is fragmented, with four Justices speaking in the plurality opinion, joined by Justice Ginsburg who concurred in the judgment separately; and four other Justices dissented in three separate opinions.
We read the holding in Egelhoff as founded on the power of the state to define crimes and defenses. The Montana statute was based on a legislative decision to resurrect “the common-law rule prohibiting consideration of voluntary intoxication” in determining whether the defendant had the requisite mens rea. — U.S. at-, 116 S.Ct. at 2020. In short, Montana decided to preclude voluntary intoxication from being asserted as a defense. The plurality explained:
“The doctrines of actus reus, mens rea, insanity, mistake, justification, and duress have historically provided the tools for a constantly shifting adjustment of the tension between the evolving aims of the criminal law and changing religious, moral, philosophical, and medical views of the nature of man. This process of adjustment has always been thought to be the province of the States.” Powell v. Texas, 392 U.S. 514, 535-536 [88 S.Ct. 2145, 2156, 20 L.Ed.2d 1254] (1968) (plurality opinion). The people of Montana have decided to resurrect the rule of an earlier era, disallowing consideration of voluntary intoxication when a defendant’s state of mind is at issue. Nothing in the Due Process Clause prevents them from doing so, and the judgment of the Supreme Court of Montana to the contrary must be reversed.
— U.S. at---, 116 S.Ct. at 2023-24.
The Montana rule excludes evidence based on the fact to be proven (voluntary intoxication) rather than on the mode of proof. Abolishing a defense is within the authority of a state legislature. On the other hand, Mil.R.Evid. 707 bars otherwise admissible and relevant evidence based on the mode of proof by categorically excluding polygraph evidence. While the plurality opinion in Egelhoff questioned whether the distinction between the fact to be proved and the method of proving it makes a difference, — U.S. at-n. 1, 116 S.Ct. at 2017 n. 1, only four Justices joined in that observation.
Justice Ginsburg pointed out in her separate concurrence in Egelhoff that the statute does not appear among Montana’s evidentiary rules but in the chapter pertaining to substantive crimes. She opines that the Montana law is “a measure redefining mens rea ” and, as such, is well within the power of a state to define crimes. — U.S. at-- -, 116 S.Ct. at 2024-25. The four Justices in the plurality opinion state that they are “in complete agreement” with Justice Ginsburg’s analysis. They explain that they “address [the statute] as an evidentiary statute simply because that is how the Supreme Court of Montana chose to analyze it.” — U.S. at---n. 4, 116 S.Ct. at 2020-21 n. 4. Justice Ginsburg, along with the four dissenters, recognized that “a rule designed to keep out ‘relevant, exculpatory evidence’ ... offends due process.” — U.S. at-, -, 116 S.Ct. at 2024, 2029.
Finally, we must comment on the dissenter’s “floodgate” argument that our opinion will generate an unreasonable burden on the services. 44 MJ at 451. Apart from the speculative nature of such an argument, we think that it is just as likely that polygraph evidence will prevent needless litigation by avoiding some meritless prosecutions as well as smoking out bogus claims of innocent ingestion. Furthermore, we are unaware of any such flood of polygraph cases after our decision in United States v. Gipson, supra. Finally, our measure should be the scales of justice, not the cash register.
Decision
The decision of the United States Air Force Court of Criminal Appeals is set aside. *449The record of trial is returned to the Judge Advocate General of the Air Force for submission to an appropriate convening authority for a hearing before a military judge. Appellant will be provided an opportunity to lay a foundation for admission of the proffered polygraph evidence. If the military judge decides that the polygraph evidence is admissible, he will set aside the findings of guilty and the sentence, and a rehearing may be ordered. If the military judge decides that the polygraph evidence is not admissible, he will make findings of fact and conclusions of law. The record will be sent directly to the Court of Criminal Appeals for expeditious review. Thereafter, Article 67, UCMJ, 10 USC § 867 (1989), will apply.
Chief Judge COX and Senior Judge EVERETT concur.