OPINION OF THE COURT
McLAUTHLIN, Judge:Was the military judge correct as a matter of law to order further tests of these accuseds’ urine samples when the samples were already reported as positive for cocaine metabolites and chain of custody was uncontested? We conclude he was not, and grant the government’s appeal.
Airman First Class (A1C) Metcalf and A1C Mosley were each randomly selected to provide urine samples for drug testing. Analysis of A1C Metcalf’s sample at the Air Force Drug Testing Laboratory (AFDTL) showed a concentration of 355 ng/ml of the cocaine metabolite benzoylecgonine (BE). A1C Mosley’s sample revealed a BE concentration of 223 ng/ml. At the time, the AFDTL’s BE cutoff level for reporting samples as positive was 150 ng/ml.1 Shortly after charges were referred, each accused requested that his sample be tested again for the presence of BE and for the cocaine metabolite ecgoninemethylester (EME). The convening authority denied both requests.
These actions were joined in one Article 39(a), UCMJ, pretrial session to evaluate the accuseds’ identical motions. In those motions, defense counsel again sought additional tests of the accuseds’ samples for BE and EME, and added requests that the samples be tested for the presence of raw cocaine. After hearing the testimony of a defense expert and a government expert, the trial judge granted *1058the defense motions and ordered all the requested tests. When notified of the convening authority’s refusal to follow his order, the judge abated the proceedings. The government has now submitted its timely appeal. Article 62, UCMJ, 10 U.S.C. § 862; see United States v. True, 28 M.J. 1 (C.M.A.1989).
The defense has not contested either samples’ chain of custody. Instead, the defense motions cited the Court of Military Appeals decision in United States v. Mack, 33 M.J. 251 (C.M.A.1991),2 and argued that “a negative EME test could indicate either that the BE test was incorrect or support the reasonable hypothesis that cocaine was added to the sample after it was ‘donated.’ ” At the Article 39(a) session, the defense expert testified that he felt a retest of the samples for BE, EME, and cocaine was “scientifically important.” He explained that, while BE and EME were cocaine metabolites produced by the body after ingesting cocaine, BE can also result from mixing raw cocaine into the urine sample itself. According to the defense expert, raw cocaine dissipates in the body after about 10 hours, EME in 40 to 48 hours, and BE in about 72 hours. Therefore, he concluded that a sample containing BE and raw cocaine but no EME could only have been “spiked” with cocaine. The defense expert added that, based upon the ratio of EME to BE in the sample, he would be able to give the Court a better indication of how much cocaine was used and when.
Both the experts agreed that BE found in an uncontaminated sample meant the person supplying the sample had used cocaine. In his cross-examination, the government expert said only about 10 grains of raw cocaine sprinkled into a urine sample would be needed to raise the sample’s BE level above the AFDTL cutoff levels. He concurred with the.defense expert’s view that the additional tests for EME and cocaine could provide more information regarding the amount of cocaine ingested and narrow the time window in which use took place. The government expert said a negative EME test of these accused’s samples would mean either that there had been use but EME was already out of the system, or that the sample had been tampered with. If raw cocaine were found in the sample with no EME, the government expert said he “probably” could render an opinion as to whether the sample had been spiked with cocaine.
Just before receiving counsel’s arguments on the motion, the judge commented,
... what I found was most interesting and what seems to be most in favor of the defense request ... is if I ordered the EME test and it proved up negative a recognized expert ... could look at a [raw] cocaine analysis and determine if the sample was spiked. And the significance of that is that even if you have the chain of custody in its present form in the litigation package which shows no breaks in the chain of custody ... if this expert testimony were to be given and if it was believed by the court members, then it would have a significant probability of leading to an acquittal. So it seems to me that it is relevant and if you have a circumstance that could lead to highly exculpatory evidence and weighing that against the relatively small cost____ It seems to me that this is not only relevant information but necessary that could lead to a change in the outcome depending on how the test results come out.
After counsel’s arguments on the motion, the military judge announced he would grant the defense request. Among his findings of fact were the following:
By testing for EME and cocaine in conjunction with the BE test, a qualified forensic toxicologist can, with a reason*1059able degree of certainty, determine whether the cocaine in the urine was ingested by the accused or was placed in the urine from an outside source, either through intentional or unintentional contamination of the sample.
The chain of custody documents are in order in both of the above cases; neither accused can point to a probable break in the chain of custody or to specific evidence supporting intentional or unintentional contamination of their urine samples. The defense in both cases is, essentially, “I never used cocaine, and I don’t know how this cocaine metabolite (BE) got in my urine sample.”
The judge concluded as a matter of law that the additional tests were relevant and that:
[t]he evidence is “necessary” as defined by the Manual for Courts-Martial because it is not cumulative of other evidence and, if the testing results are as the defense expects them to be, “will contribute to a party’s presentation of the case in some positive way on a matter in issue.” R.C.M. 703(f)(1). Indeed, this may be the only way that an accused can effectively challenge the government’s evidence on chain of custody, since an accused is at somewhat of a disadvantage in demonstrating intentional contamination of his sample or unintentional contamination in the testing process.
We are bound by the military judge’s findings of fact in this appeal unless they are clearly erroneous. United States v. Burris, 21 M.J. 140 (C.M.A.1985). Further, in an appeal by the government, we are not permitted to find facts in addition or contrary to the facts found by the military judge. Article 62(b), UCMJ; R.C.M. 908(c)(2). Our review is limited to taking action “only with respect to matters of law.” Article 62(b), UCMJ; R.C.M. 908(c)(2).
We find the trial judge’s order legally flawed. The judge’s use of R.C.M. 703(f)(1) to evaluate these requests was erroneous and led to the wrong result.3 A reading of the various subsections of R.C.M. 703(f) readily discloses that the focus of that rule is upon a party’s right to evidence already in existence—not on the right to evidence that is yet to be created.4 This is an important distinction. It is one thing for the defense to request production of existing evidence, or to seek a delay in order to investigate a possible defense, or to argue to the factfinder(s) that a reasonable doubt exists by virtue of the government’s failure to produce additional evidence; it is quite another, however, for the defense to force the government to develop additional evidence or risk abatement of the proceedings.
*1060An accused does not dictate what evidence the government will bring into court against him. Instead, the government decides when it feels the evidence is sufficient, seeks its admission in court, and argues that the evidence produced proves the accused’s guilt beyond a reasonable doubt. Either before or after the presentation of his own evidence, an accused may, through a motion for a finding of not guilty, seek a judicial determination that the government’s evidence is inadequate. R.C.M. 917. If this is unsuccessful, an accused has the opportunity to attack the government’s evidence, either its accuracy or adequacy, or both, and to argue to the factfinder that the evidence is insufficient to justify a finding of guilt beyond a reasonable doubt. Accordingly, it is not appropriate to view the accused’s motions in this case as requests that the government produce evidence, or to test them against the standard applicable to existing evidence. Instead, it is important to view the accused’s motions for what they are: requests that the government fund investigative assistance designed to develop defense evidence. See, e.g., Moore v. Kemp, 809 F.2d 702 (11th Cir.1987) (indigent defendant sought expert assistance to, among other things, possibly conduct “different and more conclusive tests” on evidence gathered by police at the crime scene). As such, they are subject to different criteria than those set forth in R.C.M.703(f)(1).
“[A]s a matter of military due process, servicemembers are entitled to investigative or other expert assistance when necessary for an adequate defense, without regard to indigency.” United States v. Garries, 22 M.J. 288, 290 (C.M.A.1986). To obtain such assistance, however, the defense must demonstrate the services are necessary for adequate representation of the accused. Garries, 22 M.J. at 291; United States v. Tomowski, 29 M.J. 578, 579 (A.F.C.M.R.1989).5 The real question becomes, then, whether these accused are entitled, as a matter of military due process, to have the government arrange to have further testing performed on the urine specimens that have already tested positive for BE. Put another way, are we prepared to say under the facts of this case, that without requiring the government to perform or contract for further testing of the specimens, these accused are denied a fair trial as a matter of law? We are not.
The Chief Judge’s dissent and the trial judge’s apparent rationale hold a certain allure: The government has the samples, the accused are “indigent,” the requested tests are relatively inexpensive, and they might produce a defense—why not run the tests? A simple cost/benefit analysis might dictate granting a request for a low cost test that could turn up some more information. The question here, however, is not whether the possible benefits of further tests outweigh their low costs, but whether these tests are, as a matter of military due process, required for a fair trial.
We must not lose sight of what the defense request seeks to produce. There is only one thing that the requested tests (for EME and raw cocaine) could possibly disclose favorable to the defense: tampering.6 The tests will not reveal the accidental spillage of “positive” urine into an otherwise “negative” sample, or the intentional contamination of one sample with another. Neither will these tests uncover the inadvertent mislabeling of urine samples, nor the intentional substitution of one sample for another. They will not show whether an accused’s food or drink was “spiked” with cocaine before consumption. The only utility these tests hold for the defense is to determine whether raw cocaine has found its way into an accused’s urine specimen. Inasmuch as we are not aware of any reason raw cocaine would be regularly *1061present near urine samples at any time throughout the collection and testing process, we must assume that inadvertent contamination is also not at issue here. Thus, the true target of these tests is limited to situations in which some person has the motive, and the opportunity, to intentionally sprinkle raw cocaine into the urine sample of an accused.
In the relative scheme of things, any and all of the possibilities cited above as not assisted by these tests are logically as likely as, or more likely than, intentional tampering by means of raw cocaine. Is our system of justice to be ground to a halt in the face of such remote contingencies? No. We apply the concept of “chain of custody” specifically to protect against such possibilities and to prevent having our justice system paralyzed by uncertainty as to the integrity of fungible evidentiary items. The government carries a burden of demonstrating, through proof of an adequate chain of custody, that the fungible evidence has been preserved in an unaltered state. United States v. Courts, 9 M.J. 285 (C.M.A.1980). This burden, once met, provides adequate due process to the persons whose urine samples must pass through a number of hands during the testing process.7
The chain of custody documentation in each of the cases at issue here is unblemished; there is no indication whatsoever of any irregularity. Nor is there the slightest hint that anyone in either chain of custody had the motive or opportunity to adulterate these accuseds’ specimens—the only thing the requested tests might disclose favorable to the defense. In this context, these accuseds’ claims of innocence, accompanied only by a hypothetical possibility of tampering, are insufficient to justify the requested assistance. See Ake v. Oklahoma, 470 U.S. 68, 105 S.Ct. 1087, 84 L.Ed.2d 53 (1985); Caldwell v. Mississippi, 472 U.S. 320, 105 S.Ct. 2633, 86 L.Ed.2d 231 (1985).8 There is simply no showing that additional testing is necessary for the adequate representation of either accused. Under these circumstances, we are constrained to find that the military judge abused his discretion when he ordered the requested tests based upon a determination that they were “necessary” under R.C.M. 703(f)(1).
Accordingly, we find that the military judge erred as a matter of law; the proceedings should not have been abated. The government’s appeal is granted, and the record of trial is returned to the military judge for further proceedings. R.C.M. 908(c)(3).
Senior Judge PRATT concurs.. On 1 January 1992, the AFDTL lowered the BE cutoff level to 100 ng/ml for reporting sampies as positive.
. In Mack, the government had performed both the BE and the EME tests on appellant’s urine sample. The BE test was reported positive, but the EME test was reported negative. According to Chief Judge Sullivan, "the Government attempted to explain this substantial and absolutely critical discrepancy in terms of general possibilities, not in terms of the particular circumstances of appellant's case.” 33 M.J. at 255. Without ”[p]roperly admitted evidence” to clarify this contradiction, Chief Judge Sullivan and Senior Judge Everett found no legally sufficient basis for appellant’s conviction. Judge Cox dissented.
. Although we do not reach our decision on this basis, we have difficulty with the judge’s R.C.M. 703 analysis itself. R.C.M. 703(f)(1) states: “Each party is entitled to the production of evidence which is relevant and necessary." (Emphasis added.) The discussion following the rule indicates that “[r]elevant evidence is necessary when it is not cumulative and when it would contribute to a party’s presentation of the case in some positive way on a matter in issue." (Emphasis added.) R.C.M. 703(f)(1) Discussion. According to the military judge, further testing would address the possibility of any "intentional or unintentional contamination” of the samples—some breach in their chain of custody. However, the point can be made that a contaminated chain of custody was never put "in issue” here.
Analogizing to another part of the R.C.M., "[a] matter is 'in issue’ when some evidence, without regard to its source or credibility, has been admitted upon which members might rely if they choose.” See R.C.M. 920(e) Discussion. As noted in the body of the main opinion, no evidence that these samples might have been tampered with was ever offered here, and the military judge found all chain of custody documentation perfectly "in order.” Absent "some evidence,” were the accuseds’ assertions that "We don’t know how this cocaine metabolite (BE) got in our urine" and mere speculation about the possibility of tampering enough to put chain of custody “in issue?” If not, retests to show possible sample tampering would not be "necessary’ under R.C.M. 703(f)(1). See United States v. Hargrove, 33 MJ. 515 (A.F.C.M.R. 1991).
Even under R.C.M. 703 analysis, the military judge erred by, in essence, equating relevance with necessity.
. R.C.M. 703(f) is entitled “Right to Evidence”. Subsections thereunder describe procedures for producing “Evidence under the control of the Government" and "Evidence not under the control of the Government.” See R.C.M. 703(f)(4)(A) and (B).
. We observe that the defense always has the option of retesting an accused's sample independently and offering those results found relevant, helpful and probative to the trier of fact. See United States v. Gipson, 24 MJ. 246 (C.M.A. 1987).
. Although the experts testified that the tests, depending upon the results, might also enable them to render a more detailed opinion as to time and amount of use, these side benefits were clearly not the basis on which the defense grounded their request.
. In criminal cases involving scientific tests, the rights of an accused are adequately protected when there is a chance to attack the reliability of the test procedure and to cross-examine testing personnel. California v. Trombetta, 467 U.S. 479, 104 S.Ct. 2528, 81 L.Ed.2d 413 (1984); United States v. Frost, 19 MJ. 509 (A.F.C.M.R. 1984).
If, as the Chief Judge suggests, due process requires that the possibility of tampering be definitively eliminated by the use of all available scientific methodology, would it not also require that the other possibilities cited above be similarly eliminated? Must the government, for instance, routinely perform DNA testing on its urine samples if such testing would scientifically eliminate the possibility that urine specimens were inadvertently or intentionally switched?
. As the Eleventh Circuit Court of Appeals explained in Moore v. Kemp:
Ake and Caldwell, taken together, hold that a defendant must demonstrate something more than a mere possibility of assistance from a requested expert; [footnote omitted] due process does not require the government automatically to provide indigent defendants with expert assistance upon demand.
809 F.2d at 712.