License plate readers have become a hot topic recently with many police departments investing in this new technology. Advocates in favor of these devices say that it will aid police in finding stolen vehicles and people with outstanding warrants while opponents believe it will lead to privacy violations, especially in the wake of the NSA revelations regarding phone monitoring. In recent years, police agencies have been using more technology such as red light cameras, speed cameras, and sidewalk cameras in order to enforce traffic laws, provide photographic evidence in case of a crime, and deterrence. However, many fear that computers taking over can only make it ripe for abuse.

License plate readers (LPRs) are typically mounted on patrol cars or stationary on a structure. LPRs are high speed cameras that use software to record passing license plates on cars. It extracts these numbers and cross checks them for various lists. If there is a match (for example, the plate number comes back as a reported stolen vehicle), the police can use that information alone to pull the vehicle over.

Grand Rapids, MI began using them earlier this year as well as Detroit, Lansing, and other Michigan cities. Some states have all but banned them. Maine requires that any date recorded from the LPRs must be destroyed within 21 days while Ohio requires that the information immediately be destroyed if there is no match. Recently, Representative Sam Singh from East Lansing began working on a bill that would require the information from LPRs be destroyed within 48 hours as well as banning pictures of the motorists.

Advocates of LPRs state that this is nothing more than a technological extension of the police doing random plate checks. Often times the police will randomly run a license plate while sitting behind a car at a stop light. If the check reveals that the plates are expired, the car is stolen, etc. then the police can pull the vehicle over. A few years ago the Sixth Circuit held that this practice was not an un-Constitutional invasion of privacy “as long as the officer had a right to be in a position to observe the defendant's license plate, any such observation and corresponding use of the information on the plate does not violate the Fourth Amendment.”[1]

The reasoning is that license plates are displayed in public and therefore no one can claim privacy in that information. What they fail to realize (or rationalize) is that while the plate number itself may be public; the information that can be obtained from the plate number is not public. For now, that's the law. At least the Supreme Court has held that the police cannot stop you just to check your identification or registration without reasonable suspicion that the driver is operating without a license or that the vehicle is not registered.[2]

What the future of LPRs and other computerized law enforcement tools is and what restraints and prohibitions legislatures decide to place on them remains to be seen. For now, they're here to stay.