Privacy v. Public Safety: Tension Continues in the Context of License Plate Recognition

Many controversial Constitutional issues involve tensions between different rights. In Con Law II we examine the standards of review that the Supreme Court uses to decide which rights outweigh others. One of the most common tensions (at least it seems) is between state’s interests and the right to privacy. This tension has surfaced again as the ACLU challenges the use of License Plate Recognition technology by law enforcement.

License Plate Recognition (LPR) is a technology that allows law enforcement to locate suspects by running license plate numbers through a database maintained by an individual state. Apparently this technology is used in every state, implying that each state also has a database. License plates are captured by cameras on police patrol cars, traffic lights, and other transportation systems. The photos are taken and stamped with the time and date.

It is a popular law enforcement technology and technique that even helped in locating the Boston bombers. Police were able to run the license plate number of one of the suspects to see places he frequented leading up to the bombing. By doing so, and following the leads, police were able to find accomplices.

While this technology has obviously helped in many cases, even in high-profile cases, and officers have expressed how important the technology is in solving cases, the ACLU has challenged its use as a violation of privacy. LPR databases do not just have license plate numbers stored for future use, but they also have photos of license plates and are able to track license plates which the ACLU believes is a breach of privacy.

The ACLU claims in its report (available at that “license plate readers can be used for tracking people’s movements for months or years on end, chilling the exercise of our cherished rights to free speech and association” (pg 8). It discusses that where we go and what we do is essential to who we are so tracking our location reveals sensitive information about us to law enforcement, possibly even without probable cause.

While this is certainly understandable, the other side appreciates the need for public safety and the role that LPR plays in accomplishing that interest. There is a tension here, as there often is, between protecting citizens and having to infringe on their rights to do so. Once again technology is at the center of a privacy debate. It will be interesting to see which right “wins out” in this particular case.

See the article at


2 thoughts on “Privacy v. Public Safety: Tension Continues in the Context of License Plate Recognition

  1. It wasn’t the Boston PD’s massive and unprecedented invasions of privacy that found Dzokhar Tsarnaev; it was attention to detail on the part of a private citizen. David Henneberry noticed that the tarp was loose on his boat, and upon investigation, he found the bloodied bomber inside. Ironically, it wasn’t until after the draconian lockdown of the city ended that Mr. Henneberry was able to locate the suspect.

    Police did use the Tsarnaevs’ license plate data to investigate after the crime. But this isn’t the kind of use opposed by the ACLU; in the pamphlet you linked, their first recommendation reads:

    License plate readers may be used by law enforcement agencies only to investigate hits and in other circumstances in which law enforcement agents reasonably believe that the plate data are relevant to an ongoing criminal investigation. The police must have reasonable suspicion that a crime has occurred before examining collected license plate reader data; they must not examine license plate reader data in order to generate reasonable suspicion.

    • Right. As I noted, they used this technology to find accomplices. Further, the ACLU is concerned with abuse of the databases which is why they included the recommendation you mentioned. They’re afraid that without standards such as having “reasonable suspicion” in order to access the databases, law enforcement would be able to abuse the information and breach our right to privacy. It’s not so much the use of LPR to find criminals that they are concerned with, but the databases and potential ability to locate and track whomever they want, even law-abiding citizens.

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