How Massachusetts Drug Cases Are Won: Suppression, Melendez-Diaz, and the Limits of the Commonwealth’s Evidence

By Attorney Joe Serpa | Georgetown University Law Center | 30 Years of Massachusetts Criminal Defense

Updated July 2026

The drug cases I am proudest of never reached a jury. They ended earlier, at a clerk-magistrate hearing, on a motion to suppress, or in a disposition that avoided a conviction altogether. That is not luck. In a Massachusetts drug prosecution under G.L. c. 94C, the most important question is usually not what the police found. It is whether they found it lawfully, and whether the Commonwealth can prove, with admissible evidence, that the substance was what the report says it was and that it belonged to my client. When the answer to either question is no, the prosecution cannot proceed. This is how I take these cases apart, in the order the issues arrive.

The Stop

Almost every street-level drug case begins with a stop, and the stop is where many of them end. A police officer needs a specific, articulable reason to stop a car or a person, tied to an observed traffic violation or to reasonable suspicion of a crime. A hunch, a label like a high-crime area, a driver who seems nervous, and a so-called drug-courier profile are not enough. Two developments have made the stop more contestable than it once was. In Commonwealth v. Long, 485 Mass. 711 (2020), the Supreme Judicial Court gave defendants a workable way to challenge a racially selective stop under the equal protection guarantee, allowing the defense to raise the issue on a totality of the circumstances rather than requiring statistics the driver could never obtain. And in Rodriguez v. United States, 575 U.S. 348 (2015), the Supreme Court held that police may not prolong a completed traffic stop, even briefly, to investigate drugs without independent reasonable suspicion, so the timeline of the stop becomes its own suppression issue. The odor of marijuana, once the workhorse of the roadside search, no longer supplies probable cause after decriminalization: the Supreme Judicial Court so held for burnt marijuana in Commonwealth v. Cruz, 459 Mass. 459 (2011), and for unburnt marijuana in Commonwealth v. Overmyer, 469 Mass. 16 (2014). The law of the roadside is collected on our page on traffic stops, exit orders, and pretext searches.

The Exit Order and the Search

A lawful stop does not authorize everything that follows it. Ordering a person out of a lawfully stopped car is a separate step that requires its own justification. In Commonwealth v. Torres-Pagan, 484 Mass. 34 (2020), the Supreme Judicial Court held that an exit order is lawful only when the officer has a reasonable belief that safety is at risk or a reasonable suspicion of criminal activity, and that a patfrisk requires a reasonable suspicion that the person is armed and dangerous. Searching the car is a further step still. The automobile exception in Massachusetts requires probable cause, and a search that outruns the facts the officer had is a search I move to suppress. Each stage of the encounter has to be justified on its own, and the general framework is treated on our page on illegal searches and seizures and in our post on when police can search your car.

The Search Warrant

Where the drugs were found on a warrant, the warrant is not the end of the inquiry. It is the beginning of one. I read the affidavit within its four corners, because that is where a magistrate had to find probable cause, and I test it for staleness, for particularity, and for informant reliability. Where there is reason to believe the affidavit contains a deliberate or reckless falsehood that was necessary to the finding of probable cause, Franks v. Delaware, 438 U.S. 154 (1978), entitles the defense to a hearing to attack it, and a warrant that survives on paper can fail once the affiant is questioned under oath.

Informants and Controlled Buys

Many drug warrants and many street stops rest on an informant, and Massachusetts tests informants more strictly than federal law does. When the Supreme Court moved to a looser totality-of-the-circumstances test for informant tips, the Supreme Judicial Court declined to follow it and retained the two-pronged standard under article 14 of the Massachusetts Declaration of Rights in Commonwealth v. Upton, 394 Mass. 363 (1985). Under that standard the Commonwealth must show both the informant’s basis of knowledge, meaning how the informant came to know what was reported, and the informant’s veracity or reliability. A tip from an unnamed source, a first-time informant with no track record, or a controlled buy that was not truly controlled can each fail that test, and when the tip does not meet the standard, the search that depended on it does not survive review.

What the Commonwealth Must Prove: Possession

Finding drugs near a person is not the same as proving that the person possessed them. When a controlled substance turns up in a shared car, a shared apartment, or a common area, the Commonwealth has to prove constructive possession, and that is a demanding standard. Under Commonwealth v. Romero, 464 Mass. 648 (2013), and the long-settled rule of Commonwealth v. Brzezinski, 405 Mass. 401 (1989), the Commonwealth must prove knowledge of the drug together with the ability and the intention to exercise dominion and control over it. Mere presence near a controlled substance, and mere association with the person who possessed it, are not enough. In a car with three occupants or an apartment with several residents, that gap between presence and possession is often the whole case.

Possession Versus Distribution

The difference between simple possession and possession with intent to distribute is often the difference between a case that can be dismissed and a case that carries real incarceration, and the Commonwealth usually proves intent by inference rather than by a witnessed sale. Quantity, packaging into separate bags, cash in small denominations, a scale, and the absence of items associated with personal use are the building blocks of that inference. Each one is contestable. A quantity consistent with personal use, packaging explained by how the drug was bought, and cash explained by a job that pays that way all cut against intent. I make the Commonwealth prove distribution rather than assume it from the fact of possession, because the charge, the exposure, and the available dispositions all turn on which one the evidence supports.

Proving the Substance: Melendez-Diaz and the Lab

The Commonwealth also has to prove that the substance was in fact an illegal drug, and that proof runs through a laboratory. In Melendez-Diaz v. Massachusetts, 557 U.S. 305 (2009), the Supreme Court held that a drug analysis certificate is testimonial, that the defendant has a Sixth Amendment right to confront the analyst who performed the test, and that the certificate cannot be admitted on its own. Massachusetts has since lived the cost of trusting the lab without question. The misconduct of the chemists Annie Dookhan and Sonja Farak led to the dismissal of tens of thousands of drug convictions, in Bridgeman v. District Attorney for the Suffolk District, 476 Mass. 298 (2017), and Committee for Public Counsel Services v. Attorney General, 480 Mass. 700 (2018). Those cases are a permanent reminder that a laboratory result is evidence to be tested, not a fact to be accepted, and I examine the chain of custody, the testing methodology, and the analyst’s qualifications in every case where the identity or the weight of the substance is contested.

Weight, Trafficking, and School Zones

Weight drives the exposure in a Massachusetts drug case, and weight is contestable. Distribution and possession with intent are charged under G.L. c. 94C, § 32 for Class A substances and § 32A for Class B substances, and the trafficking statutes add mandatory minimum sentences that climb with the alleged weight. Whether the charge rests on the aggregate weight of a mixture or the pure weight of the drug, whether the scale was calibrated, and how the police arrived at the number are all fair questions. A charge under the school-zone statute, G.L. c. 94C, § 32J, adds a mandatory sentence on top of the underlying offense, and it turns on a measured distance that the defense can require the Commonwealth to prove rather than assert. Where a case is charged at a weight or in a zone that the evidence does not support, reducing the charge changes everything that follows it.

The Discovery That Decides These Motions

A suppression motion is won on the record, not on argument, so the discovery I demand is specific. The booking video and the cruiser’s dashboard camera show what the officer saw and said in real time, and they frequently contradict the tidy narrative of a report written hours later. The computer-aided dispatch records fix the timeline of the stop to the minute, which matters under Rodriguez. The drug certificate, the laboratory’s testing worksheets, and the analyst’s chain-of-custody records are where the identity and weight of a contested substance are tested. Where the case grew out of surveillance, the pole-camera footage, the GPS records, and the surveillance logs establish what the police knew and when they knew it. I ask for all of it, because the difference between a case and a dismissal is usually sitting in the material the Commonwealth did not volunteer.

Resolving the Case Without a Conviction

Not every case should be tried, and a good result is often a disposition that leaves no conviction. For a first offense, G.L. c. 94C, § 34 allows a court to place a person on probation for simple possession and to dismiss the case on successful completion. A continuance without a finding or pretrial probation can resolve a case without a guilty finding, and the differences among them matter, as our CWOF and pretrial probation FAQs explain. For a non-citizen, the choice of disposition is decisive, because a continuance without a finding that Massachusetts does not treat as a conviction is still a conviction for federal immigration purposes, so I look for a no-admission resolution wherever one is available. The immigration stakes are set out on our page on the immigration consequences of a Massachusetts criminal charge, and for students the collateral consequences are treated on our page on college and university student defense.

The Clerk-Magistrate Stage

Where a drug case begins with an application for a complaint rather than an arrest, the first stage is also the best one. At a clerk-magistrate hearing, the defense can contest probable cause before any complaint issues, and a denial ends the matter with no entry on the person’s criminal record at all. For a student, a professional, or a non-citizen, a case that never becomes a case is worth more than an acquittal that follows an arraignment, and it is the first outcome I try to reach.

How I Defend These Cases

I represent people charged with Massachusetts drug offenses from the clerk-magistrate hearing through trial in the District Courts and the Boston Municipal Court, and I look first for the way to end the case without a conviction: a suppression motion that removes the evidence, a failure of proof on possession or on the identity of the substance, or a disposition that leaves no record. The results of that work are collected on our pages on dismissals and on how Massachusetts criminal cases get dismissed. If you are facing a drug charge in Greater Boston, call me at 617.936.0201 for a free and confidential consultation.