Massachusetts Supreme Judicial Court Suppresses Drug Evidence in Racial Profiling Case: Commonwealth v. Manuel Diaz
Why Commonwealth v. Diaz Matters for Anyone Stopped by Police in Massachusetts
In a landmark June 2025 ruling, the Massachusetts Supreme Judicial Court (SJC) reaffirmed the principle that evidence obtained through unlawful traffic stops—especially when motivated by race—cannot be used in court. In Commonwealth v. Manuel Diaz, SJC-13635, the court reversed a Superior Court judge’s ruling and held that evidence of drug trafficking found after an illegal stop must be suppressed. This case is essential reading for anyone facing charges related to drug possession or trafficking after a police stop.
If you or someone you love has been charged with a crime after a questionable police stop, this case could shape your defense. As Boston criminal defense attorneys, we at Benzaken, Maguire, Sheehan & Wood, LLP understand how to use the protections offered by Article 14 and the equal protection guarantees in the Massachusetts Declaration of Rights to fight unlawful searches and seizures.
Case Overview: A Traffic Stop, a Chase, and Cocaine Charges
The facts in Commonwealth v. Diaz are dramatic but not uncommon. On August 5, 2017, at around 9:30 PM, Officer Mark Shlosser of the Wilbraham Police Department claimed he pulled over Manuel Diaz for speeding. After the officer approached the car, Diaz fled, leading to a short chase that ended with him abandoning his car and fleeing into the woods on foot. Officers later recovered a bag of cocaine along his flight path and documents inside his car identifying him.
Diaz was later indicted for trafficking 200 grams or more of cocaine. He moved to suppress the drug evidence and the identification documents, arguing that the stop was illegal under both Article 14 (unreasonable searches and seizures) and the equal protection clauses of Articles 1 and 10 of the Massachusetts Declaration of Rights. The trial judge agreed that the stop was unlawful but held that Diaz’s flight was an “intervening act” that allowed the evidence to be admitted anyway.
The SJC disagreed—and in doing so, it delivered a powerful message about racial profiling, the exclusionary rule, and the limits of police power.
Understanding the Legal Issues: What’s the Exclusionary Rule?
One of the most important tools in a criminal defense lawyer’s toolbox is the motion to suppress. When police violate a defendant’s constitutional rights, evidence they obtain afterward is often inadmissible in court. This is known as the exclusionary rule.
The purpose of the exclusionary rule is twofold:
To deter police misconduct, and
To preserve judicial integrity by ensuring courts do not condone unconstitutional behavior.
But like many legal rules, the exclusionary rule has exceptions. One such exception is the attenuation doctrine—which asks whether the connection between the unlawful police conduct and the discovery of evidence has become so weak or “attenuated” that the taint of the illegality no longer matters.
The Diaz Case: Two Constitutional Violations, One Big Problem
In Commonwealth v. Diaz, the SJC found two separate constitutional violations:
An unlawful traffic stop under Article 14, which protects against unreasonable searches and seizures.
Racially discriminatory enforcement in violation of Articles 1 and 10, which guarantee equal protection under Massachusetts law.
The Court held that both violations triggered the exclusionary rule—and that the Commonwealth failed to prove the evidence should be admitted anyway.
Officer’s Testimony Deemed Unreliable
A key turning point in the case was the motion judge’s refusal to credit the officer’s explanation for the stop. Officer Shlosser claimed Diaz was speeding, but video, GPS, and audio evidence didn’t support that. The judge found “multiple inconsistencies” in the officer’s testimony and concluded that “the reason for the stop is a mystery.”
Even more significantly, after a special hearing conducted under Commonwealth v. Long, the judge determined that Diaz had made a strong case of racial profiling—and that the Commonwealth failed to rebut the inference that race was a motivating factor in the stop.
Why the SJC Rejected the Commonwealth’s Argument
The prosecution argued that Diaz’s act of fleeing in a car, then on foot, “broke the chain” between the illegal stop and the discovery of the drugs. This would have allowed the evidence to come in under the attenuation exception.
But the SJC rejected that theory, applying a three-factor test drawn from Commonwealth v. Borges:
Temporal proximity – How close in time was the illegal act to the discovery of evidence?
Intervening circumstances – Was there a new, unrelated event that truly broke the chain?
Purpose and flagrancy of the police misconduct – How serious was the constitutional violation?
1. Temporal Proximity
The Court found that only minutes passed between the illegal stop and Diaz’s attempt to flee and discard the drugs. This weighed against attenuation.
2. Intervening Circumstances
Diaz’s flight, though dramatic, was not enough to count as an “intervening circumstance.” The Court ruled it was a direct and immediate response to an unlawful stop, not an independent act.
3. Purpose and Flagrancy
This was perhaps the most damning for the Commonwealth. The Court emphasized that the officer’s lack of credibility itself suggested a deliberate or flagrant violation. Even more importantly, the racial motivation for the stop made the conduct inherently flagrant from an equal protection perspective.
Racial Profiling and Equal Protection: A Powerful Holding
One of the most consequential parts of this decision is the Court’s treatment of racially selective enforcement. The justices went out of their way to explain why any traffic stop motivated even in part by race violates Massachusetts equal protection law.
They also made clear that racially motivated stops are, by definition, flagrant. The Court emphasized:
“Racially selective traffic enforcement violative of equal protection is inherently flagrant.”
That’s a bold and necessary statement—one that underscores the seriousness with which Massachusetts courts now view racial profiling. It’s also a signal to defense attorneys across the state that Commonwealth v. Long has real teeth, and that motions to suppress based on racial discrimination are not just symbolic—they can win cases.
How This Affects You: Suppressing Evidence in Drug Cases
If you’re facing drug charges in Massachusetts, the evidence against you may not be admissible if it was obtained through an illegal stop. That’s true whether you were allegedly found with cocaine, fentanyl, heroin, pills, or anything else.
Here’s what you need to know:
If the stop was illegal, the evidence should be suppressed.
If your race was a factor in the stop, even partially, the stop violates equal protection.
If the police officer’s explanation is inconsistent, your lawyer can challenge the justification.
If you fled after being stopped, that does not automatically mean the evidence will come in.
Diaz’s case is a textbook example of how good lawyering, careful motion practice, and constitutional principles can intersect to protect individual rights.
What Boston Criminal Defense Lawyers Should Take Away
At our Boston criminal defense firm, we understand how to leverage the tools Commonwealth v. Diaz provides. Whether it's a case involving:
Drug trafficking,
Gun possession,
OUI,
Or other motor vehicle stops,
—we know how to challenge unconstitutional policing and get unlawfully obtained evidence thrown out.
Key strategies we use:
Motion to suppress based on lack of reasonable suspicion or probable cause
Motion to suppress based on racial profiling (Long hearing)
Cross-examination of officers whose testimony is inconsistent or unreliable
Argument against attenuation when flight or resistance follows unlawful conduct
Final Thoughts: The Power of a Motion to Suppress
In the end, Commonwealth v. Diaz is not just about one man’s case. It’s about how far the law can and should go to protect people from being stopped, searched, and prosecuted based on race or without cause. It’s about accountability and constitutional values.
If you’re facing serious charges after a car stop or arrest, the motion to suppress could be the difference between conviction and dismissal. At Benzaken, Maguire, Sheehan & Wood, LLP our experienced Boston criminal defense lawyers file these motions routinely—and we win them.
Call Us Today for a Free Consultation
If you’ve been charged with drug trafficking, gun possession, or any crime following a police stop, contact our office immediately. We know how to challenge unconstitutional searches and protect your rights. Let us put our experience, insight, and courtroom skill to work for you.