At a drug trial, a testifying expert relied on and described laboratory findings made by a non-testifying analyst. The Supreme Court held that the Confrontation Clause applies when an expert conveys an absent analyst’s testimonial statements and those statements support the expert’s opinion only if they are true. A court cannot avoid confrontation simply by labeling the statements as the basis of an opinion rather than evidence admitted for its truth. The judgment was vacated and the case remanded for the state courts to determine which statements were testimonial and address remaining evidentiary and harmless-error questions.