Forensic Drug Evidence in Massachusetts: Substitute Analysts and Confrontation

Updated August 2026

Forensic drug evidence presents two separate questions. The Commonwealth must prove the identity of the substance and, when required by the charge, its weight. It must also introduce its evidence without violating the defendant’s right to confront the witnesses against the defendant. A laboratory certificate, an analyst’s notes, raw instrument output, and a reviewing expert’s opinion do not all receive the same constitutional treatment.

The governing rule is specific. The Confrontation Clause restricts testimonial out-of-court statements offered for their truth. It does not exclude every laboratory record, require the same witness in every forensic case, or make scientific evidence inadmissible whenever more than one analyst participated. The court must identify the statement, its primary purpose, whether it is offered for its truth, and whether the testifying expert’s opinion depends on it.

This article addresses that evidentiary issue. The firm’s Massachusetts drug-crime defense page covers the underlying offenses, and the distribution and trafficking page explains when drug identity and weight become statutory elements.

Melendez-Diaz and Drug Certificates

In Melendez-Diaz v. Massachusetts, 557 U.S. 305 (2009), prosecutors introduced certificates stating that laboratory testing had identified seized substances as cocaine. The United States Supreme Court held that the certificates were testimonial. The analysts who created them were witnesses for Sixth Amendment purposes, and the prosecution could not use the certificates in place of confrontation.

The decision does not turn on whether a certificate appears reliable or whether the laboratory follows accepted procedures. The constitutional question is whether the prosecution offers a testimonial assertion from an absent witness against the defendant. Unless an exception applies, the declarant must be available for cross-examination or be unavailable after the defendant had a prior opportunity to cross-examine that witness.

Bullcoming v. New Mexico, 564 U.S. 647 (2011), applied the same principle when the prosecution introduced one analyst’s forensic certification through another laboratory witness who had not performed or observed the reported analysis. The testifying witness’s general familiarity with laboratory procedures did not provide an opportunity to cross-examine the person who made the case-specific assertions in the report.

Smith v. Arizona and an Expert’s Basis Testimony

In Smith v. Arizona, 602 U.S. 779 (2024), the prosecution called a substitute analyst who described an absent analyst’s work and then offered an opinion based on that work. The state court treated the absent analyst’s statements as nonhearsay because they explained the basis of the substitute expert’s opinion rather than proving their truth.

The Supreme Court rejected that reasoning. When an expert conveys an absent analyst’s statement to support an opinion, and the statement supports the opinion only if it is true, the statement is offered for its truth. Calling it the basis of an opinion does not avoid the hearsay question or the Confrontation Clause.

Smith did not decide whether every statement at issue in that case was testimonial. The Supreme Court remanded for the state court to address that issue. A complete analysis therefore requires both parts: the absent statement must be offered for its truth, and it must be testimonial.

Commonwealth v. Gordon and the Massachusetts Rule

Commonwealth v. Gordon, 496 Mass. 554 (2025), applied Smith to Massachusetts drug testing. The original analyst performed gas chromatography-mass spectrometry testing and recorded the procedures, protocols, and results. A crime-laboratory supervisor completed technical and administrative review but did not participate in or observe the testing. The supervisor testified to an opinion identifying the controlled substance.

The Supreme Judicial Court held that the original analyst’s case-specific notes were testimonial hearsay. Although the raw instrument output was machine generated and not itself hearsay, the supervisor’s opinion also depended on the truth of the original analyst’s statements about the processes and protocols used to produce that data. The substitute opinion was therefore not independent in the constitutional sense.

The current Massachusetts Guide to Evidence, § 703, states the resulting rule: a prosecution expert’s opinion in a criminal case may not depend on testimonial hearsay unless the declarant is unavailable and the defendant had a prior opportunity for cross-examination. The rule applies even when the prosecution does not elicit the absent analyst’s statements directly during the substitute expert’s testimony.

Gordon also addressed timing. The corrected opinion states that the holding should not apply retroactively to convictions that became final before Smith. It applies prospectively and to cases that were active or pending on direct review when Smith was issued. Whether a particular case receives the benefit of the rule therefore depends on its procedural posture.

A Substitute Expert Is Not Categorically Barred

The rule does not require courts to exclude every expert who did not personally perform each laboratory step. An expert may testify from personal knowledge about work the expert performed or observed. An expert may also form an opinion from independently admissible facts or data that are not testimonial hearsay, if the evidence satisfies the other rules governing expert testimony.

The problem arises when the opinion depends on accepting an absent analyst’s testimonial account of what occurred in the particular case. A supervisor’s credentials, general knowledge of the laboratory, or review of a file does not convert those assertions into personal knowledge. The inquiry concerns the foundation of the actual opinion, not the witness’s job title.

A witness may also describe general laboratory procedures from personal knowledge without proving that another analyst followed those procedures in the defendant’s case. The prosecution needs admissible evidence connecting the general procedure to the actual sample, preparation, testing, controls, and results on which the opinion depends.

Machine-Generated Data and Human Assertions

Pure machine output is not a statement by a person and is not hearsay on that basis. That principle does not make the surrounding human work irrelevant. A person may have selected the item, prepared a sample, entered information, chosen a method, operated the instrument, evaluated quality controls, or interpreted the output. Statements describing those case-specific acts may be necessary to make the data useful.

The court should separate the machine-generated material from the human assertions. Relevant questions include:

• What raw data did the instrument create without a human assertion?
• Who selected, weighed, prepared, or placed the sample into the instrument?
• What case-specific procedures, controls, and observations appear only in an absent analyst’s notes?
• Can the testifying expert reach the proposed opinion without accepting those statements as true?
• What evidence authenticates the data and connects it to the exhibit allegedly seized?

These questions apply beyond drug chemistry. DNA analysis, toxicology, ballistics, and digital forensics may also combine machine output with human preparation, observation, and interpretation. The constitutional result depends on the statements and testimony offered in the particular case.

Reviewing the Drug-Laboratory Record

A complete record may include the police submission form, evidence seals and identifiers, custody entries, analyst worksheets, sampling notes, weight records, standards and controls, instrument output, technical review, administrative review, and the final certificate or report. Each document serves a different purpose and may contain both machine-generated information and human assertions.

The defense should compare those materials with the witness the Commonwealth intends to call. The review can determine what the witness did personally, what the witness observed, what comes from another person, and what portions of the proposed opinion require the absent analyst’s account to be true. It can also identify ordinary authentication, reliability, sampling, or weight issues that exist independently of confrontation.

Chain of custody is one example. A gap does not automatically exclude the substance or laboratory result. Courts may treat some gaps as affecting weight rather than admissibility. The legal effect depends on the defect, the remaining foundation, and whether the Commonwealth can reliably connect the tested item to the evidence allegedly seized.

Raising and Deciding the Confrontation Issue

The issue may be presented through a motion in limine, a trial objection, a request for a detailed offer of proof, or another procedure appropriate to the case. The court needs the proposed testimony and the underlying materials to determine whether the expert will convey testimonial hearsay or offer an opinion that depends on it.

The objection should identify the absent declarant, the specific statement, the reason it is testimonial, the way it is offered for its truth, and the portion of the substitute opinion that depends on it. A general objection to a “substitute analyst” may be too broad because some testimony may concern the witness’s personal knowledge or admissible nonhearsay data.

If the court excludes testimonial statements or a derivative opinion, the effect on the charge depends on what admissible evidence remains. The Commonwealth must prove the identity of the controlled substance, but the law does not make a laboratory certificate the only possible form of proof in every case. In a trafficking prosecution, the Commonwealth must also prove the applicable net weight range. Exclusion may be decisive, or other admissible evidence may require further litigation.

Forensic Evidence Within the Complete Drug Case

Confrontation is one part of the defense. The case may also present disputes about the search, possession, intent to distribute, joint venture, sampling, drug identity, or weight. A laboratory objection does not replace those questions, and proof of a substance does not establish who possessed it or what that person intended.

The firm’s article on suppression and trial evidence in Massachusetts drug cases places forensic proof within that broader sequence. The Massachusetts drug-crimes FAQs provide shorter answers about laboratory evidence, constructive possession, searches, and suppression.

Serpa Law Office represents defendants in Massachusetts drug cases involving forensic evidence, substitute experts, possession, distribution, and trafficking. Contact the firm at 617.936.0201 to discuss the proposed evidence and the charge.