VII. The Right to Confront Expert Witnesses

The Supreme Court in 2009 first addressed the question of whether prosecution-sponsored experts can be "witnesses against the accused" for confrontation purposes.²⁰² In Melendez-Diaz v. Massachusetts,²⁰³ the prosecutor had introduced three sworn and notarized "certificates of analysis"²⁰⁴ that identified the white powder seized from the defendant as cocaine.²⁰⁵ Under state law, the certificates provided prima facie evidence of the composition, quality, and weight of a tested substance.²⁰⁶

In Melendez-Diaz, Justice Scalia wrote for Justices Stevens, Souter, and Ginsburg.²⁰⁷ The plurality concluded that the laboratory certificates were testimonial statements requiring confrontation because (1) they were affidavits; (2) they were "made under circumstances which would lead an objective witness reasonably to believe that the statement would be available for use at a later trial";²⁰⁸ and (3) "we can safely assume that the analysts were aware of the affidavits' evidentiary purpose."²⁰⁹ The plurality's first rationale defined the limits of the Court's holding because it was the only point of agreement with Justice Thomas, who provided the fifth vote.²¹⁰

In Bullcoming, Justice Kennedy wrote for the four Melendez-Diaz dissenters (he was joined by Chief Justice Roberts and Justices Alito and Breyer). Their disagreement with the plurality was profound. In the dissenters' view, "witnesses against the accused" must be read as limited to typical conventional/adversarial prosecution witnesses and cannot be extended to experts who have "witnessed nothing to give them personal knowledge of the defendant's guilt."²¹¹ These justices complained that the Court was now "dictat[ing] to the States, as a matter of constitutional law, an as-yet undefined set of rules governing what kinds of evidence may be admitted without in-court testimony. . . . [and] without guidance from any established body of law."²¹² They also anticipated that future courts would struggle to identify the "analyst" among the "many people [who] play a role in a routine test for the presence of illegal drugs."²¹³ Finally, the four dissenters predicted that Melendez-Diaz would "disrupt forensic investigations across the country and put prosecutions nationwide at risk of dismissal based on erratic, all-too-frequent instances when a particular laboratory technician, now invested by the Court's new constitutional designation as the analyst, simply does not or cannot appear."²¹⁴

Although Melendez-Diaz seemed to settle the question of whether out-of-court statements by prosecution experts raised confrontation concerns,²¹⁵ over the next three years the Supreme Court would grant certiorari in three new expert witness cases. The first was Briscoe v. Virginia,²¹⁶ which involved the question of whether providing a criminal defendant with the opportunity to subpoena prosecution experts adequately protects the right to confrontation. The case was remanded to the Supreme Court of Virginia after oral argument.²¹⁷ The Court in Bullcoming v. New Mexico²¹⁸ held that the Confrontation Clause was violated when the prosecutor introduced a laboratory report through the in-court "surrogate testimony" of an expert witness (Razatos) who was familiar with the lab procedures, but "did not sign the certification or perform or observe the test reported in the certification."²¹⁹ The justices rejected the argument that the prosecution expert (Caylor) who had performed the blood alcohol test (but did not testify) did not make a testimonial statement but was a mere scrivener who transcribed results generated by machines.²²⁰ According to the Bull-coming majority, "the operation of the machines requires specialized knowledge . . . [s]everal steps are involved in the gas chromatograph process, and human error can occur at each step."²²¹ Thus, the admission of Caylor's testimonial statement via trial testimony from Razatos deprived the defendant of the opportunity to "raise before the jury questions concerning Caylor's proficiency, the care he took performing his work, and his veracity."²²² Although the laboratory report at issue in Bullcoming was unsworn, the Court found that it contained adequate formalities to qualify as a testimonial statement.²²³

In Bullcoming, Justice Sotomayor wrote a separate concurring opinion to emphasize that her conclusion was based on the fact that the laboratory report "has a primary purpose of creating an out-of-court substitute for trial testimony,"²²⁴ and to map the limits of her concordance with the majority. According to Justice Sotomayor, "this is [a] not a case in which an expert was asked for his independent opinion about underlying testimonial reports that were not themselves admitted into evidence,"²²⁵ which apparently would have led her to a different conclusion. As discussed in the following sections, the precise question anticipated by Justice Sotomayor subsequently came before the Court the following term in Williams v. Illinois.²²⁶

Unsurprisingly, the four Melendez-Diaz dissenters (Chief Justice Roberts and Justices Alito, Breyer, and Kennedy) also dissented in Bullcoming. In their view, Bullcoming was another unnecessary and unwarranted extension of Crawford that only "forbid[s] sworn, ex parte, out-of-court statements by unconfronted and available witnesses who observed the crime and do not appear at trial,"²²⁷ a definition that does not include experts. Once again, the dissenters faulted the majority for displacing states' authority to devise their own fair trial procedures²²⁸ and "extending and confirming Melendez-Diaz's vast potential to disrupt criminal procedures"²²⁹ as supported by new empirical evidence cited by various amici.²³⁰

The Supreme Court continues to revisit the confrontation of prosecution-sponsored experts.²³¹ In People v. Williams, the Illinois Supreme Court had permitted the prosecutor to introduce the in-court testimony of a prosecution expert (Lambatos) who did not perform or observe the DNA testing described in the laboratory report, but testified that he evaluated and analyzed the underlying data and the DNA report.²³² The state court found that Lambatos' testimony regarding the DNA report (which was not proffered or admitted in evidence) did not violate the Confrontation Clause because the evidence had been admitted not "for the truth of the matter asserted" but for the limited purpose of enabling the jury to assess the basis of the testifying expert's opinion.²³³ This argument is analogous to the widely accepted position that a testimonial statement offered to impeach need not be confronted, because the statement was not offered for the truth of the matter asserted but for the limited nontruth purpose of impeachment (i.e., jurors need not believe the impeaching statement to doubt the witness's credibility).

In June 2012, the case came before the Supreme Court as Williams v. Illinois. Justice Alito, writing for a plurality that included the other Bullcoming and Melendez-Diaz dissenters (Chief Justice Roberts, Justice Kennedy, and Justice Breyer), found that Lambatos' testimony did not violate the Confrontation Clause.²³⁴ Justice Alito's opinion was grounded in his conclusion that Lambatos' testimony was not offered to prove the truth of the matter asserted.²³⁵ However, the plurality also noted that even if the Cellmark report had been admitted, there would have been no constitutional violation because the report was nontestimonial because it "was not sought for the purpose of obtaining evidence to be used against petitioner, who was not under suspicion at the time."²³⁶ The plurality emphasized the distinction between this case and Melendez-Diaz and Bullcoming. In these earlier cases, the lab reports at issue had been formally certified to ensure their admission at trial.²³⁷ As in Melendez-Dia...