Commonwealth v. McCarthy: License Plate Reader Technology Can Trigger Constitutional Protections
by Jessie J. Rossman
Case Focus
In this age of increasing government monitoring of citizens in public spaces, the use of automated license plate readers (ALPRs) by law enforcement agencies has significantly increased the capacity for government surveillance of Massachusetts drivers on the roads and streets. A recent case decided by the Supreme Judicial Court suggests some limits on this surveillance.
ALPR systems capture and retain photographs of every license plate number that comes into view, along with the time, date and location. These systems can retain millions of historical records for months or years on end, and send real-time alerts on any license plate number entered into a “hot list.” According to one recent national survey, in 2016 and 2017 alone 173 law enforcement agencies scanned a total of 2.5 billion license plates.
In Commonwealth v. McCarthy, 484 Mass. 493 (2020), the Supreme Judicial Court addressed ALPRs for the first time. Although the Court affirmed the denial of defendant Jason McCarthy’s motion to suppress the warrantless search of data from four fixed ALPR units that captured information about his vehicle, the Court made clear that it would reach a different conclusion in cases involving more pervasive ALPR systems.
McCarthy joins a growing line of SJC and United States Supreme Court cases addressing the privacy implications of evolving surveillance technology. The Fourth Amendment of the United States Constitution and Article 14 of the Massachusetts Declaration of Rights protect an individual’s reasonable expectations of privacy from warrantless government intrusion. Technology has dramatically increased police officers’ surveillance capacity, overcoming the practical constraints and civilian oversight that historically checked such powers, and in doing so, has provided access to categories of information previously unknowable.
Mindful of these dangers, the SJC and SCOTUS have responded to ensure scientific advancements do not destroy traditional expectations of privacy. As the SJC emphasized in Commonwealth v. Almonor, 482 Mass. 35, 41 (2019), “both this Court and the United States Supreme Court have been careful to guard against the power of technology to shrink the realm of guaranteed privacy by emphasizing that privacy rights cannot be left at the mercy of advancing technology but rather must be preserved and protected as new technologies are adopted and applied by law enforcement.” Reflecting this understanding, the highest courts in the Commonwealth and the country have held that the police must obtain a warrant based on probable cause to conduct long-term GPS tracking of a car (Commonwealth v. Rousseau, 465 Mass. 372 (2013) and Commonwealth v. Connolly, 454 Mass. 808 (2009)), to obtain more than six hours of historical cell site location information (CSLI) from a cellphone, (Carpenter v. United States, 138 S. Ct. 2206 (2018), Commonwealth v. Augustine, 467 Mass. 230 (2014), and Commonwealth v. Estabrook, 472 Mass. 852 (2015)), and to use electronic surveillance of a cellphone to obtain real-time location information (Almonor).
McCarthy applied these established principles to a different surveillance-technology: ALPRs. Since 2015, the Massachusetts State Police has operated four ALPRs on the Sagamore and Bourne Bridges. Their cameras automatically feed images into a database maintained by the Executive Office of Public Safety and Security (EOPSS). As part of a narcotics investigation, the Barnstable Police Department searched for the appearance of McCarthy’s license plate in historical and real-time ALPR data from these four cameras without obtaining a warrant. In his motion to suppress, McCarthy argued that this warrantless access violated his constitutionally protected reasonable expectations of privacy, while the District Attorney suggested that art. 14 and the Fourth Amendment did not apply to these images because McCarthy knowingly exposed them to the public. Denying the motion, Superior Court Judge Robert Rufo opined, “[p]erhaps the defendants’ argument would be stronger if the ALPR Hot List was set to issue an Alert every time McCarthy’s vehicle passed any of the ALPR cameras installed at a multitude of locations statewide,” before noting that, “such a scenario is not in keeping with the facts before this court[.]”
The SJC took Judge Rufo’s reasoning one-step further. It affirmed that accessing ALPR data from “four cameras placed at two fixed locations on the ends of the Bourne and Sagamore bridges” did not trigger constitutional protections. But the Court went on to emphasize “[w]ith enough cameras in enough locations, the historic location data from an ALPR system in Massachusetts would invade a reasonable expectation of privacy and would constitute a search for constitutional purposes.” While the SJC did not demarcate the specific threshold that would require a warrant, it did provide some helpful guidance.
First, applying case law developed through cases involving GPS and CSLI, the SJC made clear that its precedents were anchored not in the particular type of technology used to conduct surveillance, but in the type of information collected via that technology. To that end, the SJC confirmed that technology which allows the police to “travel back in time,” obtain “real-time location data,” or conduct surveillance for a period of time that “drastically exceeds what would have been possible with traditional law enforcement methods,” will trigger constitutional protections.
Second, the SJC set forth some guideposts for future ALPR cases. It noted that EOPSS’ year-long retention period for ALPR data “certainly is long enough to warrant constitutional protection.” It also indicated that even a limited number of ALPRs may still trigger constitutional protections when they are placed “near constitutionally sensitive locations” such as “the home [or] a place of worship” that “reveal more of an individual’s life and associations[.]”
Finally, Chief Justice Gants’ concurrence proposed an “analytical framework that might prove useful in future cases.” He suggested a warrant could be required for ALPR data that created a sufficiently detailed picture to be “the type of mosaic that would constitute a search,” and reasonable suspicion could be required for ALPR data that was less revealing of the individual’s movements “but greater than the four location points established in this record[.]” This “would mean that law enforcement agencies would need to obtain court authorization more often before retrieving targeted individual historical locational information in their possession because queries that would not require a showing of probable cause might still require a showing of reasonable suspicion.” Chief Justice Gants also warned that, “unless the law enforcement agency has sought prior court approval to search for particularized locational data in its possession, the agency will have to preserve each and every search query for the retrieval of historical locational information regarding a targeted individual” and make it “available in discovery when sought by the defendant.”
McCarthy does not provide all of the answers regarding ALPRs. Additional clarity will ultimately come from future Court cases or new legislation to confer explicit privacy protection on data gathered by ALPRs and other caches of aggregated personal information. McCarthy already makes clear, however, that ALPR data can—and at a certain threshold does—trigger constitutional protections and the warrant requirement.
Jessie J. Rossman is a staff attorney at the American Civil Liberties Union of Massachusetts (ACLUM) and one of the authors of an amicus brief submitted in Commonwealth v. McCarthy on behalf of ACLUM, the Committee for Public Counsel Services, the Electronic Frontier Foundation, and the Massachusetts Association of Criminal Defense Lawyers.
