Master Fractured Supreme Court decision on whether a prosecution expert may relate a non-testifying lab’s DNA profile without violating the Sixth Amendment Confrontation Clause. with this comprehensive case brief.
Williams v. Illinois sits at the crossroads of evidence law and the Sixth Amendment’s Confrontation Clause, testing how far prosecutors can go when presenting forensic science through an expert who did not perform the underlying analysis. The case arose in the wake of Crawford, Melendez-Diaz, and Bullcoming—decisions that tightened confrontation protections against the admission of testimonial forensic statements without live testimony from the analyst. Williams presented a partial retreat, at least on its facts, by allowing an expert to relay the substance of a third-party laboratory’s DNA profile in a bench trial.
But Williams is notoriously fractured. A four-Justice plurality treated the lab material as either non-testimonial or not offered for its truth; Justice Thomas concurred only in the judgment on a narrow formality-based rationale; and four dissenters would have found a Confrontation Clause violation. Consequently, Williams generated uncertainty in lower courts over whether, and when, surrogate expert testimony about lab results is permissible. That uncertainty has been substantially addressed by the Court’s later clarification in Smith v. Arizona (2024), which rejected the plurality’s “not-for-truth” path for basis testimony and underscored that expert-relayed statements used to support an opinion are typically offered for their truth.
567 U.S. 50 (2012)
In 2000, police collected a rape kit from the victim (identified as L.J.) in Illinois. Facing a backlog, the Illinois State Police (ISP) laboratory sent the vaginal swabs to Cellmark, a private lab, to generate a DNA profile from semen found on the swabs. Cellmark produced a DNA profile and returned it to the ISP lab. Later, after Sandy Williams became a suspect, the ISP lab developed a DNA profile from Williams’s known blood sample. At Williams’s bench trial for sexual assault, the State called Sandra Lambatos, an ISP forensic analyst who did not work at Cellmark. Lambatos testified that the DNA profile she created from Williams’s blood “matched” the DNA profile that Cellmark had generated from the vaginal swabs. The prosecution did not introduce the Cellmark report as an exhibit, nor did it call any Cellmark analyst. The defense objected on Confrontation Clause grounds, arguing that Lambatos was serving as a surrogate to relay testimonial statements by non-testifying Cellmark analysts. The trial judge overruled the objection, emphasizing that, in a bench trial, he would consider the Cellmark material only for the limited purpose of explaining the basis of Lambatos’s opinion. Williams was convicted, the Illinois Supreme Court affirmed, and the U.S. Supreme Court granted certiorari.
Does the Confrontation Clause permit a prosecution expert to testify to a DNA “match” by relating a non-testifying laboratory’s DNA profile when the underlying report is not admitted and the analyst who performed the testing does not testify?
Under the Confrontation Clause, testimonial statements of a witness absent from trial are inadmissible unless the witness is unavailable and the defendant had a prior opportunity to cross-examine (Crawford v. Washington). In the forensic context, sworn or formalized lab certifications prepared for prosecution are testimonial (Melendez-Diaz v. Massachusetts), and the prosecution generally may not introduce such results through a surrogate witness (Bullcoming v. New Mexico). Williams did not produce a single majority rule: a four-Justice plurality concluded that an expert’s basis testimony referencing a third party’s DNA profile did not violate confrontation because the statements were not offered for their truth and/or were not testimonial; Justice Thomas concurred in the judgment on the narrower ground that statements lacking sufficient formality and solemnity are not testimonial. Accordingly, the judgment in Williams stands for the limited proposition that, on those facts, admitting an expert’s opinion that referenced a third party’s DNA profile did not violate the Confrontation Clause. Subsequent authority, however, clarifies that when an expert conveys a non-testifying analyst’s statements in support of the expert’s opinion, those statements are ordinarily offered for their truth and trigger confrontation requirements (Smith v. Arizona, 2024).
Affirmed. The admission of the expert’s testimony referencing the Cellmark DNA profile did not violate the Confrontation Clause on the facts presented. A four-Justice plurality reasoned the statements were either not offered for their truth or were non-testimonial; Justice Thomas concurred in the judgment because the Cellmark statements lacked the requisite formality to be testimonial.
Plurality (Alito, joined by Roberts, Kennedy, Breyer): The plurality advanced two independent rationales. First, it characterized the Cellmark DNA profile information as not offered for its truth but only to explain the basis of Lambatos’s expert opinion that Williams’s known profile matched the source of the semen; in a bench trial, the judge could and did consider it for that limited purpose. Second, the plurality concluded that the Cellmark statements were not testimonial under the primary-purpose test because the DNA profile was generated before any suspect had been identified; its primary purpose was to help find an at-large perpetrator, not to accuse a particular, known individual. The plurality also emphasized that the Cellmark report itself was not admitted, and it stressed the permissibility of experts relying on inadmissible material to form opinions (akin to Federal Rule of Evidence 703). Concurrence in the judgment (Thomas): Justice Thomas rejected the plurality’s “not-for-truth” reasoning and its primary-purpose analysis but agreed with the result. He proposed a narrower testimonial test focused on “formality and solemnity.” Because the Cellmark materials lacked the formal attributes (such as a sworn affidavit or certificate) that characterized the lab statements in Melendez-Diaz and Bullcoming, he deemed them non-testimonial. On that basis alone, he found no Confrontation Clause violation. Dissent (Kagan, joined by Scalia, Ginsburg, Sotomayor): The dissent viewed the Cellmark statements as classic testimonial evidence: they were made for the purpose of establishing facts in a criminal prosecution, and the prosecution used them substantively to prove the truth that the semen profile came from L.J.’s swabs and matched Williams. The dissent rejected the plurality’s non-hearsay characterization as an end-run around the Confrontation Clause, noting that the expert’s testimony conveyed the substance of the out-of-court statements for their truth. It also rejected the idea that the absence of a targeted suspect or the bench-trial posture eliminated confrontation concerns. In the dissent’s view, Melendez-Diaz and Bullcoming controlled and required reversal. Precedential effect and later clarification: Because no single rationale commanded a majority, Williams provided, at most, a narrow result tied to its facts. Many courts treated Justice Thomas’s concurrence as the narrowest ground under Marks, limiting the case to statements lacking formalized, sworn attributes. In Smith v. Arizona (2024), the Supreme Court clarified that when an expert relays a non-testifying analyst’s statements as the basis for an opinion and the probative value of the opinion depends on the accuracy of those statements, the statements are effectively offered for their truth and trigger the Confrontation Clause. Smith declined to treat Williams as controlling and substantially undercut the plurality’s “not-for-truth” approach to basis testimony.
For law students, Williams illustrates both the complexity of Confrontation Clause analysis in forensic evidence cases and the difficulties of applying fractured Supreme Court opinions. It sits between Melendez-Diaz/Bullcoming’s robust confrontation protections and later clarification in Smith v. Arizona. Practically, Williams was long read to permit limited expert testimony referencing third-party lab work where the report was not admitted, the statements lacked formal solemnity, and no particular suspect had been targeted. Post-Smith, prosecutors should assume that relaying an absent analyst’s statements to support an expert’s opinion will generally trigger confrontation requirements, and defense counsel should object when such statements are used substantively without producing the analyst. Williams remains important as a teaching case about plurality reasoning, the primary-purpose and formality inquiries, the interaction with evidentiary rules (e.g., Rule 703), and the doctrine’s evolution.
No. Williams is a fractured decision. A four-Justice plurality and a one-Justice concurrence reached the same result for different reasons, so no single rationale commanded a majority. Many courts treated Justice Thomas’s formality-based concurrence as the narrowest ground. In Smith v. Arizona (2024), the Court clarified that the Williams plurality’s “not-for-truth” approach to expert basis testimony is not controlling.
The plurality leaned on the idea that experts may rely on inadmissible materials to form opinions. It treated the out-of-court DNA profile as background that explained the expert’s opinion rather than as substantive evidence. The dissent countered that when the expert’s opinion’s probative value depends on the truth of the out-of-court statements, those statements are functionally admitted for their truth and trigger the Confrontation Clause—a view later embraced in Smith v. Arizona.
The plurality emphasized the bench-trial posture, trusting the judge to consider the Cellmark material only for a limited, non-hearsay purpose. The dissent responded that confrontation rights apply equally in bench trials and that the State used the Cellmark statements substantively. Post-Smith, the bench-trial fact does not eliminate confrontation issues when the expert conveys testimonial statements for their truth.
Under Crawford and its progeny, statements are testimonial when their primary purpose is to establish or prove past facts for use in a criminal prosecution. The Williams plurality thought a DNA profile generated before a suspect was identified was primarily aimed at finding an at-large offender, whereas Justice Thomas focused on whether the statement bore sufficient formalized, solemn attributes (e.g., sworn certifications). The dissent found the statements testimonial regardless, given their clear prosecutorial use.
Not to introduce the results themselves. Melendez-Diaz and Bullcoming bar using a surrogate to present a testimonial certification. Williams allowed an expert to offer an opinion that referenced a third-party profile without admitting the report and where the statements lacked formal solemnity. After Smith v. Arizona, however, if the expert conveys the absent analyst’s statements in a way necessary to substantiate the opinion, those statements are treated as offered for their truth and will generally require that the analyst testify or be subject to prior cross-examination.
Williams v. Illinois is a pivotal Confrontation Clause case for understanding how forensic evidence and expert testimony intersect. It illustrates the tension between evidentiary rules permitting experts to rely on out-of-court information and constitutional guarantees that the accused may confront the witnesses against him. The case also exemplifies the challenges posed by fractured Supreme Court opinions and the care courts must take in extracting a controlling rule.
In practice, Williams briefly opened a narrow path for expert testimony referencing third-party lab work without live testimony from the analyst. Yet the Court’s later decision in Smith v. Arizona makes clear that when an expert’s opinion depends on the truth of an absent analyst’s statements, confrontation is required. For litigators and students alike, Williams remains an essential study in doctrinal evolution, methodological pluralism on the Court, and the limits of surrogate expert testimony in criminal trials.