When Cambridge announced it was halting the use of automatic license-plate reader technology pending review of data-sharing practices, the decision reflected more than a policy debate. It exposed an emerging evidentiary fault line under Article 14 of the Massachusetts Declaration of Rights. At the same time, Brookline’s consideration of privately owned plate readers with police access demonstrates how quickly surveillance systems can expand beyond traditional public control. Together, these developments offer meaningful insight for defense counsel assessing whether the Commonwealth relied on warrantless, technology-driven tracking to build its case.
When prosecutors present evidence drawn from automated plate readers, defense strategy should center on three questions: how long the data was stored, whether it was shared with outside entities, and whether law enforcement used cumulative scans to reconstruct a person’s movements across time. Each of these factors directly influences whether the collection qualifies as a “search” under Article 14.
How ALPR Surveillance Becomes a Constitutional Issue
Automatic license-plate readers capture images of every vehicle passing a fixed or mobile camera. Over days and weeks, those snapshots can form a detailed map of where a person lives, works, shops, and travels. While the Supreme Judicial Court has not yet found that brief ALPR use violates privacy protections, it has warned that persistent or widespread surveillance could. The Court’s reasoning in Commonwealth v. McCarthy and Commonwealth v. Mora,, establishes that aggregation of public movements over time may cross the threshold into a constitutionally protected zone. The difference lies not in what a single camera records, but in the government’s ability to combine thousands of scans into a portrait of private life.
Building a Record Through Discovery
The first step in any suppression challenge is developing the factual record. Counsel should request complete documentation of the ALPR system used in the investigation. Essential materials include the city or state’s data-retention policy, all agreements with private vendors, lists of agencies with access rights, audit logs showing external queries, and the physical locations of each active camera during the period in question. Each category provides evidence of scale and reach. A system that records months of data and is shared among multiple jurisdictions supports the argument that the surveillance extended far beyond the limited observation of a single traffic camera.
Standing, Scope, and Particularity
Prosecutors often claim the accused lack standing because vehicles travel on public roads. That argument overlooks the central concern of modern privacy doctrine. Article 14 protects against government actions that collect and combine data to reveal patterns of private conduct. The defense should insist on particularity regarding which cameras were used, the time frame of each query, and how those queries were linked to the accused. By narrowing the factual record, the Court is better positioned to assess whether the search exceeded permissible boundaries.
Lessons from Cambridge and Brookline
Cambridge’s decision to pause its ALPR system raises questions about reliability, data integrity, and vendor oversight. When a municipality publicly acknowledges uncertainty about how it handles its information, that acknowledgment undermines confidence in the evidentiary chain. Brookline’s proposal, which relies on privately installed cameras with police access, introduces an additional concern: the potential blurring of public authority and private surveillance. If a vendor retains independent control over data or distributes it to third parties, the Commonwealth cannot credibly argue that such information was obtained within lawful investigative limits.
Using These Developments in Motion Practice
Those facing charges supported by plate-reader data should not treat the evidence as routine. A thoughtful motion to suppress can expose how expansive these systems have become and whether officers used technology to bypass judicial authorization. By tying factual disputes to the privacy principles articulated in McCarthy and Mora, the defense can argue that long-term, aggregated monitoring constitutes an unreasonable search under Article 14. Courts must then determine whether the government’s reliance on automated surveillance crosses the constitutional line.
Protecting Your Rights in the Age of Constant Tracking
The rise of automated monitoring technology demands careful legal attention. Each scan may seem minor, but together they can tell a detailed story about your life, one that the government should not collect without proper judicial review. If your case involves ALPR evidence, you deserve counsel who understands both the technology and the law that governs its use.
Call the Law Office of Patrick J. Murphy at (617) 367-0450 for a confidential consultation. Our office reviews each record, identifies potential privacy violations, and builds a defense grounded in current Massachusetts precedent.