By Joshua K. Saucier
Originally published in Volume 33, Issue 2 of the National Traffic Law Center (NTLC)’s Between the Lines February 2025 issue.

Forensic toxicologists offer critical testimony in impaired driving cases, and admissibility of their testimony may be more challenging in light of last year’s U.S. Supreme Court decision, Smith v. Arizona.[1] Toxicologists’ testimony is often used by prosecutors to inform juries of the drugs in a defendant’s body while that person was driving; toxicologists’ testimony is also used by prosecutors to inform juries of the physiological responses and human behaviors that are consistent with persons having consumed a given drug.[2] The scientific process involved in isolating and identifying a drug in a person’s blood involves several steps: collecting the sample, transporting the sample to the lab, assigning it to a particular person or department for analysis, analyzing the sample (screening and confirmation), reporting the results, and interpreting the results (including quality control and quality assurance measures). Labs prioritize obtaining accurate results and value efficient processes. Toward that end, some labs use batch processing, which can involve multiple analysts handling a specimen for complete toxicological analysis. Consequently, batch processing may lead to the forensic toxicologist interpreting the results of an analysis being a different person than the analyst who tested the sample.

A similar situation arose in Smith v. Arizona when a chemist who did not test the sample testified about the results obtained by another chemist.[3] This testimony was the basis for a Confrontation Clause[4] challenge.[5] Ultimately, the Court ruled in favor of the defendant, but the reasoning did not inherently prohibit the use of all “substitute analysts.”[6] As a result, prosecutors must carefully consider whether calling[7] a substitute analyst[8] as a witness in an impaired driving case satisfies the right of the defendant to “be confronted with the witnesses against [them].”[9]

Smith: The Facts

In December 2019, Yuma County (AZ) Narcotics Task Force law enforcement officers executed a search warrant on the house of Jason Smith’s father.[10] As the officers approached a shed on the property, they smelled the odor of marijuana.[11] After announcing themselves and knocking on the shed door, Jason Smith (“Smith”) opened said door.[12] Smith was forcibly removed from the shed, and the officers found what they believed to be the following: marijuana plant material, “cannabis wax,” methamphetamine, and various items of drug paraphernalia.[13]

The suspected drug samples were sent to Arizona’s state laboratory for testing, and a chemist performed testing to identify the seized drugs.[14] The chemist, Rast, performed analyses, created a file, and generated notes and certificates of analysis for the file.[15] She opined that the samples contained the same illegal drugs that law enforcement suspected.[16] When it came time for trial, however, Rast no longer worked for the State of Arizona.[17] Given this, another state chemist reviewed and analyzed Rast’s work.[18] This chemist, Longoni—using Rast’s work—came to the same conclusions as Rast.[19] Longoni then testified at trial, indicating his opinion was that the items were drugs and cited Rast’s work as support for his opinion.[20] Indeed, Longoni’s testimony often referred to Rast’s work.[21]

Specifically, Longoni testified that—based on Rast’s notes—standard lab procedures were followed: that the scientific methods used included microscopic examination, a chemical color test, and other examinations; that blanks were run to avoid contamination; and that based upon such information and more, he formed independent opinions as to the contents of the suspected drug samples.[22]

Smith challenged the admission of Longoni’s testimony, and his opinions based on the Confrontation Clause.[23]

Smith: The Confrontation Clause Rules

The Sixth Amendment of the U.S. Constitution guarantees a criminal defendant the right to confront the witnesses against them.[24] When an out-of-court statement is introduced into evidence and the defendant is not afforded the opportunity to cross-examine the witness who made the statement, this right might be violated.[25] The test to determine if a statement may be introduced in court is whether the out of court statement is (1) hearsay and (2) testimonial.[26] If those two things are true, then the statement is not admissible under the Confrontation Clause.[27]

If an out of court statement is offered for its truth, then it is hearsay, and the first prong of the test is met.[28]

To determine if a statement is testimonial, courts look to “primary purpose” of the statement.[29] Specifically, courts will look to the reason that the statement was made and its relation, if any, to criminal proceedings.[30] If a statement was made with primary purpose to “accuse a target individual or create evidence” or “establish or prove past events potentially relevant to later criminal prosecution,” then it is testimonial and, if also hearsay, is inadmissible under the Confrontation Clause.[31]

Smith: The Arguments

In Smith, the defendant argued that Longoni’s testimony violated the Confrontation Clause. Specifically, Smith argued that Rast and not Longoni was “the real witness against him,” and allowing Longoni to testify prevented Smith from effectively cross-examining the person who reached the scientific conclusions.[32]

The state argued that Rast’s statements, admitted through Longoni, were not offered for their truth.[33] Instead, the state said, the statements were offered as a basis for Longoni’s independent conclusions.[34] In other words, the state argued that because the statements were not offered for their truth, they could not be considered “hearsay,” and their admission could not, therefore, violate the Confrontation Clause (i.e., the first prong of the test was not met).

Importantly, the state did not argue that the statements were non-testimonial: it made only the non-hearsay (not for the truth) argument.[35] As such and as further discussed below, the trial court did not fully consider whether the statements of Rast were testimonial. The trial court did, however, allow Longoni’s testimony finding that none of it was hearsay.[36] Smith appealed the trial court’s decision to Arizona Court of Appeals, division one, which affirmed the trial court’s decision.[37] The Supreme Court of the State of Arizona declined to review the case,[38] and the United States Supreme Court granted certiorari (i.e., the Court decided to review the case).[39]

[1] 602 U.S. 779 (2024).
[2] See ANSI/ASB, ANSI/ASB Best Practice Recommendation 037: Guidelines for Opinions and Testimony in Forensic Toxicology 3–4 (1st ed. 2019)
[3] Smith v. Arizona, 602 U.S. 779, 789–791 (2024).
[4] U.S. Const. amend VI (“In all criminal prosecutions, the accused shall enjoy the . . . to be confronted with the witnesses against him.”).
[5] Smith, 602 U.S. at 791.
[6] See id. at 800, 802–03.
[7] Or attempting to call.
[8] For this article, a “substitute analyst” is a witness called to testify and offer opinion evidence at trial in place of another technician who performed the laboratory testing or examination. Such substitute analysts have been used in a wide range of cases from a medical examiner relying on the autopsy performed by another doctor, see State v. Mercier, 2014 ME 28, ¶¶ 9–14, 87 A. 3d 700, 704, to a toxicologist relying on the chemical analysis performed by another chemist of a suspect’s blood sample, see, e.g., State v. Romano, 268 N.C. App. 440, 452–53, 836 S.E.2d 760, 771–72 (2019).
[9] U.S. Const. amend VI.
[10] State v. Smith, No. 1 CA-CR 21-045, 2022 Ariz. App. Unpub. LEXIS 552, at *1-2, 2022 WL 2734269 (Ariz. Ct. App., July 14, 2022) (hereinafter
“Smith Unpub.”); Pett. App. 3a, Smith v. Arizona, 602 U.S. 779 (2024) (No.22–899) (hereinafter “Pett. Appendix”).
[11] Smith Unpub., at *2; Pett. Appendix 3a.
[12] Smith Unpub., at *2; Pett. Appendix 3a–4a.
[13] Smith Unpub., at *2–3; Pett. Appendix 4a.
[14] Smith, 602 U.S. at 789–90.
[15] Id. at 790.
[16] See id.
[17] Id.
[18] Id. at 790–91.
[19] Id. at 791.
[20] Id.
[21] Id.
[22] Id.
[23] Id.
[24] U.S. Const. amend VI.
[25] See Crawford v. Washington, 541 U.S. 36, 38–40, 60 n.9, 68–69 (2004).
[26] See id.; Davis v. Washington, 547 U.S. 813, 817–18, 819–20, 828–29, 829–32; Melendez-Diaz v. Massachusetts, 557 U.S. 305, 307, 311 (2009).
[27] See Crawford, 541 U.S. at 38–40, 68–69; Bullcoming v. New Mexico, 564 U.S. 647, 651–52, 657–58 (2011).
[28] Crawford, 541 U.S. at 60 n.9; Anderson v. United States, 417 U.S. 211, 219 (1974).
[29] See Davis, 547 U.S. at 822; Williams v. Illinois, 567 U.S. 50, 82–84 (2012). Note that Justice Thomas would also require the statements to be of a formal nature akin to testimony. See Williams, 567 U.S. at 103 (Thomas, J. concurring); but see Davis, 547 U.S. at 825–26 (rejecting the notion that the Confrontation Clause protects against only formal statements).
[30] See Davis, 547 U.S. at 827–29; Williams, 567 U.S. at 84–85.
[31] Williams, 567 U.S. at 84; Davis, 547 U.S. at 822.
[32] Smith, 602 U.S. at 791.
[33] See id. at 791–92.
[34] Id.