Melendez-Diaz v. Massachusetts

Supreme Court of the United States · 2009 · Evidence

557 U.S. 305 (2009)

Updated August 1, 2026

Evidenceforensic certificatesconfrontationConfrontation Clausetestimonial statementsaffidavitsforensic analysiscertificates of analysis

Facts

Police detained Thomas Wright after observing suspicious activity and found four plastic bags containing a substance resembling cocaine. After arresting Wright and two men in the car, including Melendez-Diaz, officers later found another plastic bag containing 19 smaller bags hidden in the police cruiser. At trial, the prosecution introduced the seized bags and three sworn certificates of analysis from state laboratory analysts reporting the weight of the seized bags and stating that the substances contained cocaine. Melendez-Diaz objected that the analysts had to testify in person under the Confrontation Clause, but the trial court admitted the certificates under Massachusetts law as prima facie evidence of the substances' composition and weight.

Issue

Whether sworn certificates of forensic analysis stating that seized substances contained cocaine are testimonial statements, so that the analysts who made them are witnesses subject to the defendant's Sixth Amendment right of confrontation.

Rule

A witness's testimony against a defendant is inadmissible unless the witness appears at trial or, if unavailable, the defendant had a prior opportunity for cross-examination. Sworn forensic certificates created for the sole purpose of proving a fact at trial are affidavits and therefore fall within the core class of testimonial statements covered by the Confrontation Clause.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In Phoenix, police seized a white powder from Jordan Pike during a narcotics investigation. At trial, the prosecutor offered a notarized laboratory certificate signed under oath by an analyst at Sonoran Metro Forensic Center stating that the substance weighed 18 grams and tested positive for methamphetamine; the analyst did not appear, and Jordan had no prior chance to cross-examine her.

Is the certificate admissible over Jordan's Sixth Amendment objection?

Explanation. The majority held that sworn forensic certificates prepared to establish a fact for use at trial are affidavits within the core class of testimonial statements. Such evidence is inadmissible unless the declarant appears or is unavailable and the defendant previously had an opportunity to cross-examine. Reliability, neutrality, or the lack of a direct accusation does not remove the statement from the Confrontation Clause.