Smith v. Arizona
The Supreme Court ruled that when a prosecutor's substitute expert relays an absent lab analyst's specific findings to the jury as the foundation for the expert's own opinion, those findings are being used as truth — giving the defendant a constitutional right to cross-examine the original analyst.
The decision resolves a decade of confusion in courts across the country and limits how prosecutors can use substitute experts to route around defendants' right of confrontation in cases involving forensic evidence.
How it got here: Smith was convicted in Arizona state court; the Arizona Court of Appeals affirmed his conviction; Smith petitioned the Supreme Court, which agreed to hear the case.
The Case in Depth
What happened
Arizona police arrested Jason Smith and sent seized items to a state crime lab, where analyst Elizabeth Rast tested them and concluded they contained meth, marijuana, and cannabis. Rast left her job before trial for unexplained reasons. Rather than call Rast, the State brought in a different analyst, Greggory Longoni, who had no involvement in the original testing. Longoni read through Rast's notes and report, relayed her findings to the jury item by item, and then offered what the State called his own "independent opinion" — arriving at the same conclusions Rast had.
The question before the Court
Can a prosecutor use a substitute forensic expert to relay an absent lab analyst's findings to the jury — calling them the "basis" of the substitute's own opinion — without giving the defendant a chance to cross-examine the original analyst?
The Court's answer
No — when a prosecutor's substitute expert relays an absent analyst's specific lab findings to support the substitute's own opinion, those findings come into evidence for their truth. The Court reasoned that the substitute's opinion is only credible if the underlying facts reported by the original analyst are true: the jury accepts the expert's conclusion only by first accepting the truth of the absent analyst's factual assertions. Labeling the relay as "basis evidence" under state evidence rules cannot change that constitutional reality.
Because Rast's statements were used for their truth, the Confrontation Clause's protections were potentially triggered — but only if those statements were also "testimonial." The Court did not decide the testimonial question because it had not been decided by the lower courts and was not squarely presented for review. The case was sent back to the Arizona Court of Appeals to resolve that issue first, including whether the State forfeited the argument entirely by not raising it below.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Prosecutors across the country have routinely called substitute forensic experts to relay absent analysts' lab findings — avoiding the need to produce the original tester at trial. This ruling tightens that practice significantly: defendants now have a stronger constitutional claim to cross-examine the analyst who actually did the lab work in drug, DUI, and other forensic-evidence cases, and prosecutors will need to ensure testifying experts stick to permissible ground.
What changes now
The case returns to the Arizona Court of Appeals, which must first decide whether the State forfeited any argument that Rast's notes and report were not "testimonial." If that argument survives, the court must then decide whether those records qualify as testimonial under the Confrontation Clause. If they do, Smith's conviction would likely need to be reconsidered. If the records are found non-testimonial, the Confrontation Clause poses no bar and the conviction may stand.
What this does not decide
The Court did not decide whether Rast's lab notes and signed report were "testimonial" — the separate constitutional threshold for the Confrontation Clause to apply at all. The Court also did not bar forensic experts from testifying generally about lab practices, or from answering hypothetical questions; only relaying specific out-of-court findings as factual truth was ruled impermissible.
Concurrences and dissents
Concurrence in part — Justice Thomas
Justice Thomas joined the majority's core holding that basis evidence is offered for its truth, but declined to join Part III, which offered guidance on the 'primary purpose' test for deciding whether a statement is 'testimonial.' He argued that the Confrontation Clause applies only to statements in formalized materials — such as affidavits, depositions, prior testimony, or confessions — and that on remand the Arizona courts should ask whether Rast's records have the requisite formality and solemnity, not focus on the speaker's primary purpose.
Concurrence in part — Justice Gorsuch
Justice Gorsuch also joined the majority's hearsay holding but not Part III. He wrote separately to express deeper skepticism about the 'primary purpose' test itself — questioning whether it finds support in the Constitution's text or founding-era history, and warning that it leaves judges without a principled anchor. He worried that Part III's guidance, offered for a question not properly before the Court, may inadvertently restrict confrontation rights.
Concurrence — Justice Alito
Justice Alito, joined by Chief Justice Roberts, concurred only in the judgment — agreeing that Longoni went too far in this specific case but rejecting the majority's broader rule that basis testimony is always offered for its truth. He argued the majority had inflicted unnecessary damage on modern evidence law: the Federal Rules of Evidence already allow this kind of expert testimony (with limiting instructions preventing jurors from treating it as truth), and courts have long presumed juries follow such instructions. He would have vacated on the narrower ground that Longoni specifically testified to the truth of facts he had no personal knowledge of.
How the Court got there
The legal reasoning, step by step
- The Sixth Amendment's Confrontation Clause bars prosecutors from introducing an absent witness's out-of-court statements at trial unless those statements are both 'hearsay' (offered to prove the truth of what they say) and 'testimonial' (made with a legal, court-focused purpose). The Court addressed only the hearsay half here.
- The State argued that Longoni's relay of Rast's findings was not hearsay because it was admitted only to 'show the basis' of his independent opinion — a purpose allowed by Arizona's evidence rules. The Court rejected this outright: the scope of a federal constitutional right is not defined by state or federal evidentiary rules.
- The Court held that basis evidence of this kind is necessarily offered for its truth because the substitute expert's opinion is useful to the prosecution only if the absent analyst's underlying facts are true. The jury can credit the opinion only by accepting what the absent analyst reported. The Court found 'no meaningful distinction' between admitting the statements to explain an expert's opinion and admitting them for their truth.
- The Court illustrated this with the trial record: Longoni had zero personal knowledge of Rast's testing yet testified as fact that she followed standard protocols, used specific methods, and ran a 'blank' to avoid contamination — all drawn solely from her records. He 'effectively became Rast's mouthpiece,' and his drug-identity opinions held value only because the jury accepted Rast's account of her lab work as true.
- Approving Arizona's approach, the Court said, would hollow out its earlier decisions in Melendez-Diaz (which barred introducing a lab report without its analyst) and Bullcoming (which barred using any surrogate analyst to convey another's certified findings), allowing any testimonial lab report to reach the jury through a trained but uninvolved substitute.
- The Court declined to decide whether Rast's records were 'testimonial' — the separate threshold question. That issue was not ruled on below and was not part of the question the Court agreed to review. It remanded to the Arizona Court of Appeals, directing that court to determine both whether the testimonial argument was forfeited and, if not, whether the records qualify as testimonial.
Doctrinal impact
Cases affected by this decision
Reaffirms Melendez-Diaz v. Massachusetts (557 U. S. 305)
Reaffirmed that defendants have the right to cross-examine the lab analyst who prepared a forensic report.
Reaffirms Bullcoming v. New Mexico (564 U. S. 647)
Reaffirmed that a state cannot introduce one analyst's findings through any uninvolved surrogate analyst.