Forensic Drug Evidence in Massachusetts: Substitute Analysts and Confrontation

Updated August 2026

The Commonwealth must meet two separate requirements when it offers forensic drug evidence. The Commonwealth must prove the identity of the substance and, when required by the charge, its weight. The Commonwealth 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 Confrontation Clause restricts testimonial out-of-court statements offered for their truth. The Confrontation Clause does not require the exclusion of 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 the confrontation issue in forensic drug evidence. 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 the certificates were witnesses for Sixth Amendment purposes. The prosecution could not use the certificates in place of confrontation.

The question whether the Confrontation Clause applies to a certificate does not depend on whether the 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. The declarant must be available for cross-examination or be unavailable after the defendant had a prior opportunity to cross-examine that witness, unless an exception applies.

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 the state court’s reasoning. An absent analyst’s statement is offered for its truth when an expert conveys the statement to support an opinion and the statement supports the opinion only if it is true. Calling the statement the basis of an opinion does not avoid the hearsay question or the Confrontation Clause.

In Smith, the Supreme Court did not decide whether every statement at issue was testimonial. The Supreme Court remanded the case for the state court to address whether the statements were testimonial. A complete analysis therefore has two parts. The absent statement must be offered for its truth and must also be testimonial.

Commonwealth v. Gordon and the Massachusetts Rule

In Commonwealth v. Gordon, 496 Mass. 554 (2025), the Supreme Judicial Court 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. The raw instrument output was machine generated and was not itself hearsay. The supervisor’s opinion, however, also depended on the truth of the original analyst’s statements about the processes and protocols used to produce the instrument 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.

In Gordon, the Supreme Judicial Court also addressed the cases to which the rule applies. The corrected opinion states that the holding should not apply retroactively to convictions that became final before Smith. The holding applies prospectively and to cases that were active or pending on direct review when Smith was issued. The question whether a particular case receives the benefit of the rule therefore depends on the procedural posture of the case.

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.

A confrontation problem arises when the expert’s 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 the absent analyst’s 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. The rule for machine output 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 that describe the human work in the particular case may be necessary to make the data useful.

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

• 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 form the proposed opinion without accepting the absent analyst’s statements as true?
• What evidence authenticates the data and connects it to the exhibit allegedly seized?

The questions in the list above 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 the laboratory records with the witness the Commonwealth intends to call. The defense can use the review to 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. The defense can also use the review to identify ordinary authentication, reliability, sampling, or weight issues that exist independently of confrontation.

Chain of custody is one example of an issue that exists independently of confrontation. A court does not automatically exclude the substance or laboratory result because of a gap in the chain of custody. Courts may treat some gaps as affecting weight rather than admissibility. The legal effect of a gap 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 confrontation 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.

The effect on the charge depends on what admissible evidence remains if the court excludes testimonial statements or a derivative opinion. 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. In some cases the Commonwealth cannot prove the charge without the excluded evidence. In other cases the parties litigate further over the remaining admissible evidence.

Forensic Evidence Within the Complete Drug Case

The confrontation challenge is one part of the defense in a drug case. A drug case may also involve disputes about the search, possession, intent to distribute, joint venture, sampling, drug identity, or weight. The other disputes remain in the case even when the defense raises a laboratory objection. Proof of a substance does not establish who possessed the substance or what that person intended.

The firm’s article on suppression and trial evidence in Massachusetts drug cases discusses forensic proof together with the other issues in a drug case. 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.