Smith v. Arizona
The Supreme Court ruled that prosecutors cannot use a substitute forensic expert to relay an absent lab analyst's findings and evade a defendant's right to confront the actual analyst, because those relayed findings necessarily come into court to prove the truth of what they assert.
The decision resolves a decade-long split among courts in the wake of a fractured 2012 ruling and significantly limits how prosecutors can use substitute experts when the scientist who actually performed lab testing is unavailable for trial.
How it got here: Smith was convicted at trial; the Arizona Court of Appeals affirmed, holding the substitute expert testimony was permissible; the Supreme Court agreed to hear Smith's appeal.
The Case in Depth
What happened
Jason Smith was found in a shed in Arizona with a large quantity of what appeared to be drugs and drug paraphernalia. A state forensic analyst named Elizabeth Rast tested the items and documented her findings in detailed notes and a signed report, concluding the substances included methamphetamine, marijuana, and cannabis. Before trial, Rast left the lab for unexplained reasons. Rather than call Rast, the State substituted a different analyst, Greggory Longoni, who had no involvement in the original testing but relayed Rast's findings to the jury and offered his own "independent opinion" based entirely on her records.
The question before the Court
When a substitute forensic expert relays an absent lab analyst's findings as the "basis" for the expert's own opinion, do those out-of-court statements come into court for their truth — triggering a defendant's right to confront the absent analyst?
The Court's answer
Yes — when a substitute expert's opinion rests on an absent analyst's findings, and those findings are what makes the opinion credible, the findings come into court for their truth. The Court rejected Arizona's argument that labeling such evidence the "basis" of an expert's opinion removes it from the Confrontation Clause's reach. Because the jury can only credit the expert's conclusion by first believing the underlying facts the absent analyst reported — that she performed certain tests, followed certain procedures, got certain results — those statements are being used precisely for their truth. State evidence rules cannot change that federal constitutional reality.
The Court did not decide whether Rast's notes and report were "testimonial," the separate prerequisite for Confrontation Clause protection. That question — and the threshold dispute over whether Arizona gave up the right to contest it — was sent back to the Arizona Court of Appeals to resolve first.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Prosecutors across the country routinely call substitute forensic experts when the original analyst is unavailable. Under this ruling, such substitutes can no longer simply relay what the absent analyst found and label it mere "basis" for their own opinion — defendants now have a constitutional right to cross-examine the analyst who actually did the testing. This most directly affects drug prosecutions and other cases that turn on forensic lab results.
What changes now
The case returns to the Arizona Court of Appeals to resolve two remaining questions: first, whether Arizona forfeited any argument that Rast's notes and report were not "testimonial"; and second, if not forfeited, whether those records were in fact testimonial under the Confrontation Clause. If the state court finds the statements testimonial (or that the issue was forfeited), Smith's drug convictions could be overturned. If the court finds the statements were not testimonial, they are outside the Confrontation Clause's reach and the convictions may stand.
What this does not decide
The Court did not decide whether the absent analyst's specific notes and report were "testimonial" — the independent prerequisite for Confrontation Clause protection. It also did not rule on whether forensic records created primarily for quality control, lab accreditation, or personal reminders (rather than for court use) would be testimonial in other cases.
Concurrences and dissents
Concurrence in part — Justice Thomas
Justice Thomas joined Parts I, II, and IV of the majority opinion — agreeing that basis testimony comes in for its truth — but declined to join Part III, which discusses what makes a statement 'testimonial.' He continues to hold that the Confrontation Clause applies only to statements with the formality and solemnity of historical practices like affidavits, depositions, prior testimony, and confessions — not to whatever a 'primary purpose' test might sweep in. On remand, he would have the Arizona court ask whether Rast's statements had the requisite formality, not what their primary purpose was.
Concurrence in part — Justice Gorsuch
Justice Gorsuch also joined Parts I, II, and IV, agreeing that relabeling absent-analyst statements as mere 'basis' evidence does not remove them from the truth inquiry. He refused to join Part III both because the testimonial question was not properly before the Court and because he questioned whether the 'primary purpose' test is the right constitutional framework at all. He flagged multiple founding-era meanings of 'witness' and 'testimony' that might protect defendants more broadly, and warned that the primary-purpose test is judge-made and potentially indeterminate.
Concurrence — Justice Alito
Justice Alito agreed that the judgment should be vacated but sharply criticized the majority for broadly ruling that expert basis testimony is always offered for its truth, calling it a needless wound on modern evidence law. He argued that Federal Rule of Evidence 703 — which replaced the widely condemned hypothetical-question system over fifty years ago — already handles the line correctly, with probative-value balancing and limiting instructions to prevent misuse. Alito would have reached the same outcome on narrow grounds: Longoni violated the Confrontation Clause (and the Federal Rules) specifically when he testified as fact that Rast actually ran certain tests and followed certain procedures, but experts should still be permitted to convey the general basis for their opinions under appropriate safeguards.
How the Court got there
The legal reasoning, step by step
- The Confrontation Clause bars the admission of 'testimonial hearsay' — out-of-court statements introduced to prove the truth of what they assert — from absent witnesses. Courts must independently determine whether a statement serves that function; state evidence rules that label something 'not for the truth' (like Arizona's Rule of Evidence 703) do not control this federal constitutional inquiry.
- The Court contrasted this case with Tennessee v. Street (a 1985 decision), where an accomplice's confession was admitted to show differences from the defendant's own statement — not to prove the truth of the murder narrative the confession contained. In that situation, the truthfulness of the out-of-court statement was irrelevant to the purpose for which it was used, so the Confrontation Clause was not implicated.
- Here, by contrast, the absent analyst's findings were useful to the prosecution only if true. Substitute expert Longoni could offer an opinion that the seized substances were marijuana and methamphetamine only because he accepted as true Rast's account of what tests she ran, what procedures she followed, and what results she obtained. An expert's opinion built on fabricated or mistaken lab work is worthless — so the truth of the underlying findings is what gave the testimony its entire value.
- The same conclusion follows from the jury's perspective: a juror deciding whether to trust the substitute expert's opinion must first evaluate whether the absent analyst's factual account is accurate. That is assessing the statement for its truth — exactly the evaluation the Confrontation Clause is designed to subject to cross-examination. Because Rast was never in the courtroom, Smith had no opportunity to probe her methods, her accuracy, or her honesty.
- The Court held that approving Arizona's approach would make its prior decisions in Melendez-Diaz and Bullcoming — which applied the Confrontation Clause to forensic reports — a dead letter: any testimonial lab report could reach a jury through any trained surrogate, and defendants could never cross-examine the analyst who actually did the work. The Court noted that experts like Longoni can still usefully testify from personal knowledge about general lab procedures, accreditation standards, or by answering hypothetical questions — but they cannot be mere mouthpieces for an absent colleague's records.
- The separate question of whether Rast's records were 'testimonial' — which turns on the 'primary purpose' for which they were created and their relationship to potential criminal proceedings — was not addressed by the lower courts and was not part of the question the Court agreed to hear. The Court sent that issue, including a dispute over whether Arizona forfeited its right to raise it, back to the Arizona Court of Appeals to decide in the first instance.
Doctrinal impact
Cases affected by this decision
Reaffirms Crawford v. Washington (541 U.S. 36)
The Confrontation Clause bars absent witnesses' testimonial statements regardless of a court's reliability assessment; cross-examination is the required test.
Reaffirms Melendez-Diaz v. Massachusetts (557 U.S. 305)
Forensic lab reports are subject to the Confrontation Clause; defendants have the right to cross-examine the analysts who prepared them.
Reaffirms Bullcoming v. New Mexico (564 U.S. 647)
A state cannot introduce one analyst's lab findings through the testimony of a substitute analyst who did not participate in the testing.
Limits Williams v. Illinois (567 U.S. 50)
The plurality's 'not for the truth' rationale for admitting expert basis testimony is rejected; courts may no longer rely on it to sidestep the Confrontation Clause.