Massachusetts License Plate Reader Laws

Status at a glance

No ALPR statute

We found no enacted Massachusetts statute governing license plate readers. Several bills have been filed in the Legislature, but none that we found has become law. That means there is no statewide rule on permitted uses, retention, sharing, alert-based stops or audits. Those questions are governed by constitutional law and by each agency’s own policy.

Commonwealth v. McCarthy

In Commonwealth v. McCarthy (2020), the Supreme Judicial Court considered ALPRs that State police had installed on both sides of the Bourne and Sagamore bridges, the routes onto and off of Cape Cod. Police used historical data on the defendant’s crossings and put his plate on a hotlist for real-time alerts.

The court held that data from four cameras at fixed points on two bridges was not a search under the Fourth Amendment or the Massachusetts constitution. The cameras showed only when the vehicle went onto or off of the Cape, not the whole of the defendant’s movements. But the court warned: “With 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.”

The court didn’t set a number. It said the record didn’t show how many cameras existed or detected the defendant, so evidence about the actual network can shape the analysis. A Flock deployment can involve far more cameras than four. How a court would treat a dense network is the question McCarthy left open. See the mosaic theory.

Article 14

McCarthy analyzed both the Fourth Amendment and Article 14 of the Massachusetts Declaration of Rights. Whether Article 14 gives broader protection than the Fourth Amendment for location data is on our research list, starting with Commonwealth v. Augustine (2014). The official copy we tried to retrieve was blocked, so we haven’t verified what it holds.

An example: Billerica’s Flock policy

Billerica Police Department Policy INV-22, “Automated License Plate Readers (ALPRs): FLOCK,” took effect October 5, 2026. The department uses stationary Flock Safety cameras. This is one town’s policy, not a statewide rule, and other Massachusetts agencies may differ.

• Authorized purposes. The policy says reasonable suspicion or probable cause isn’t required before using an ALPR, but use is limited to eleven listed purposes. The first is “Investigation of a criminal offense when there is reasonable suspicion that a criminal offense was committed.” Others include missing persons, warrants, stolen vehicles and exigent circumstances (VI.B–C).
• Retention. “All data is stored and encrypted by Flock Safety for seven (7) days. Thereafter, ALPR data is purged unless it has become, or it is reasonable to believe it will become, evidence in a criminal or civil action or is subject to a discovery request or other lawful action to produce records.” Such data is downloaded and booked into evidence (IX.A).
• Alerts. “An ALPR ‘hit’ shall not be used as a reason to make contact until all provisions contained in this section have been met.” The officer visually verifies the hotlist entry against the image and gets confirmation from NCIC, the MDT or dispatch. An alarm alone “shall not be a basis for any law enforcement action” (VIII).
• Audits. “The Program Manager will conduct weekly audits of Searches and Hot Lists created by officers and purge or update lists as necessary” (VI.H). The Program Manager can also access a search audit log (IX.C). Manual hotlist entries expire after seven days unless re-issued (VI.F).
• Sharing and public access. Data may be shared only with law enforcement or prosecutorial agencies on an approved written request, or as otherwise permitted by law. Other requests are processed as public records requests (XI). The policy describes the data as confidential: “it is not open to public view” (II.B).

The policy creates no evidentiary remedy.

What this can mean in a Massachusetts case

• How many cameras were in the network, where were they, and how many captured the vehicle? McCarthy said the record on these points matters.
• Did police use stored historical data, real-time alerts, or both?
• Which agency’s policy applies? Under a 7-day policy like Billerica’s, how was older data preserved, and on what basis?
• Was the use within the policy’s listed purposes, and what does the search audit log show? See ALPR audit logs and search records.
• For a stop on an alert, was the hit confirmed before contact? See ALPR alert traffic stops.