We granted this application for interlocutory appeal to consider the trial court’s denial of defendant Weston D. Cronkite’s motion for a certificate of need for testimony under OCGA § 24-10-90 et seq., The Uniform Act to Secure the Attendance of Witnesses from Without the State (“the Act”). Cronkite sought to obtain, among other things, the “source code” or human-readable programming instructions for the Intoxilyzer 5000, by means of the testimony of a representative of the Kentucky manufacturer. The trial court concluded that such evidence was not “material” within the meaning of OCGA § 24-10-94 (a), and declined to issue a certificate. Because the trial court did not abuse its discretion in so concluding, we affirm.
After Cronkite was stopped for speeding on January 15, 2010, he submitted to a breath test using an Intoxilyzer 5000, which returned readings of 0.187 and 0.201. Cronkite was arrested and charged with speeding, driving under the influence per se, and driving under the influence to the extent he was a less-safe driver. The parties stipulated that Cronkite has a surgical implant in his upper jaw and a retainer on his lower teeth.
Before trial, Cronkite filed a motion pursuant to OCGA § 24-10-90 et seq. for “an [ojrder finding that the computer source code of the Intoxilyzer 5000 ... is material, relevant and necessary to preparing *58the defense in this criminal prosecution.” He also sought “other required assembly tools and compiler tools that are necessary for proper software evaluation,” and
copies of the manufacturer’s software assembly requirements and software specifications, any linked objects/files with comments preserved therein, and with any message digest (MD5) file signatures, information, documentation, and identification as to the software maker for the machine (if outsourced from [the manufacturer]), any compiled code, data tables and any associated (MD5) file signatures, as well as any systems “Test and Validation” plans studies or reports.
Finally, he sought to subpoena one or more out-of-state witnesses to produce the source code.1
At the hearing on his motion, Cronkite presented Matthew Malhiot, a “forensic breath alcohol consultant,” as an expert witness.2 Malhiot testified regarding the operation of the Intoxilyzer 5000, the internal calibration of the machine, and the role of the software, including the source code, in controlling its internal calibration. Specifically, he testified that the software is designed to generate error messages in “numerous” circumstances that might produce an erroneous reading, including the presence of excess alcohol in the mouth. The witness described the manner in which the software determined the presence of mouth alcohol but testified that, without knowledge of the parameters established in the source code, he could not determine the range or “cutoff... for a particular error message.”
While Malhiot testified at some length regarding the potential for errors in the source code of the software used in the Intoxilyzer 5000, he had never examined the source code itself and could not determine that any error actually existed in the absence of the source code.3 He found no indication that an invalid sample was obtained in Cronkite’s case and could not determine whether mouth alcohol was present. He acknowledged that he could not testify “for a fact” that the presence of implants or partial dentures trapped excess alcohol and affected the test results in this case: “It’s not necessarily absolute. *59It can cause it.” He also acknowledged that the Intoxilyzer had “safeguards” which were designed to produce an error warning in the presence of excess alcohol in the mouth.
The trial court’s ruling from the bench, in its entirety, was as follows:
[Defense counsel]... just had a very... impressive witness. So I’m very impressed with the witness. I’m not going to agree with your argument, though. I think you had good evidence; you had, I guess, the strongest type of argument you can make given the facts of our case here. But I’m not going [to] find that he’s material, although, you know, like I indicated, he certainly was very credible.
(Emphasis supplied.) In its written order, the trial court expressly found that the evidence sought was not “material under the facts of this case” and made no findings with respect to the expert’s credibility. The trial court issued a certificate of immediate review, and this court granted Cronkite’s application for an interlocutory appeal.
OCGA § 24-10-94 (a) provides:
If a person in any state which by its laws has made provision for commanding persons within its borders to attend and testify in criminal prosecutions, or grand jury investigations commenced or about to commence, in this state is a material witness in a prosecution pending in a court of record in this state or in a grand jury investigation which has commenced or is about to commence, a judge of such court may issue a certificate under the seal of the court stating these facts and specifying the number of days the witness will be required. The certificate may include a recommendation that the witness be taken into immediate custody and delivered to an officer of this state to assure his attendance in this state. This certificate shall be presented to a judge of a court of record in the county in which the witness is found.
Our Supreme Court has defined the term “material witness” within the meaning of this statute as “a witness who can testify about matters having some logical connection with the consequential facts” of the case. (Citation and punctuation omitted.) Davenport v. State, 289 Ga. 399, 404 (711 SE2d 699) (2011). We review the trial court’s ruling under an abuse of discretion standard. See id. at 399.
Applying this standard, we conclude that the trial court did not abuse its discretion in declining to issue a certificate. The ruling *60correctly distinguished between the credibility of Malhiot and his testimony, and the materiality to this case of the evidence sought by Cronkite through the manufacturer’s representative. To hold otherwise would require a court to issue a certificate whenever a testifying witness was found credible.
Although an expert may testify to his opinion,
when the basis of his opinion is given and it appears that it is wholly speculative or conjectural, it must follow that his opinion is without foundation and has no probative value. Speculation and conjecture by an expert is still speculation and conjecture, and will not support a verdict.
(Citation, punctuation and emphasis omitted.) Layfield v. Dept. of Transp., 280 Ga. 848, 850 (1) (632 SE2d 135) (2006). Here, in sum, Malhiot’s testimony was that, although he could not testify to any facts supporting the existence of an error in Cronkite’s breath test results, and the Intoxilyzer had safeguards against the error in question, it was possible that the software contained some unknown flaw that could have affected the test results. The witness was not required, as the dissent asserts, to demonstrate an error in the source code. He was, however, required to testify to some fact indicating the possibility of an error in this case, and the trial court did not abuse its broad discretion in finding that he failed to do so.
The question presented here is not whether the source code itself, without which the Intoxilyzer will not function, has “some logical connection” with the consequential facts of this case, as proposed by the dissent. Were that the case, the source code would be relevant to every breath test resulting in a DUI prosecution in Georgia. Rather, the question is whether the trial court could have concluded, in the exercise of its discretion, that the testimony presented at the hearing failed to provide any evidence of an error in the source code that was material to this case. Some evidence of such an error is the consequential fact that would render testimony regarding the source code logically connected to the issue presented here.
As to this question, the witness was only able to speculate; and just as speculation will not support a verdict, it likewise cannot support a finding of materiality.4 Otherwise, anyone with evidence *61sought by a party could be rendered a “material witness” merely by speculation that examination of the evidence sought might reveal some material fact.
Here, Malhiot’s testimony, though found worthy of belief by the trial court, does not establish the materiality of the evidence sought sufficiently to show an abuse of discretion. The trial court was well within its broad discretion to conclude that Malhiot’s testimony with respect to the source code was speculative and to decline to issue a certificate on that basis.
Judgment affirmed.
Ellington, C. J., Andrews and Dillard, JJ., concur. Barnes, P. J., Phipps, P. J., and Doyle, P. J., dissent.Yeary v. State, 289 Ga. 394, 398 (711 SE2d 694) (2011), allows the movant for such a certificate to identify a corporation as the alleged material witness without designating a particular representative, but in his motion Cronkite identified three individuals whose testimony he sought.
While Malhiot did not testify to any training or education in reading or interpreting source code, the parties stipulated to his expertise solely “for the specific narrow issue as to the materiality certificate.”
He also testified that Georgia has multiple versions of the source code in use.
While the dissent correctly observes that admissibility is distinct from materiality, a finding of materiality under OCGA § 24-10-94 (a) must nevertheless be supported by admissible and probative evidence. The rules of evidence are the same in all courts unless otherwise provided by statute, OCGA § 24-1-3, and the determination that a witness is a “material witness” must itself be supported by admissible evidence. Moreover, the trial court is auth*61orized to use its discretion in determining the weight to assign to a witness’ speculation on a finding of materiality.