The pros and cons of license-plate reader technology

As police departments look to implement new ways to catch criminals, one emerging technology is the use of automatic license plate readers (APLRs). These are camera systems that scan images of license plates, allowing law enforcement "to identify and compare plates against those of cars driven by people suspected of being involved in illegal activities," according to the U.S. Department of Homeland Security. ALPRs recently helped lead to the arrest of a Los Angeles man suspected of quadruple homicide. Without ALPRs, "this individual that we believe is responsible for at least four murders may have been out there and re-offended," said Los Angeles County Sheriff Robert Luna.

Despite the obvious benefits of alleged criminals being taken off the streets, opponents of ALPR technology have raised concerns about privacy, as well as issues about the tech's accuracy. 

Pro: It helps catch criminals

ALPRs can help police arrest criminals. Beyond the aforementioned murder suspect in Los Angeles, ALPRs have resulted in the arrests of alleged carjackers, rapists, bank robbers and even a mass shooter in Atlanta. "Those cameras proved extremely helpful," law enforcement told WRAL-TV of the latter, adding that police were able to get a hit off their ALPR systems and "[find the] precise location of the building he walked into." During a four-month trial period in Wichita, Kansas, ALPRs "helped police make 156 arrests, a majority of which were felony cases, and recover 23 guns and 152 stolen vehicles," Kevin Cox reported for American Police Beat magazine.   

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Con: It can be inaccurate

The technology is improving, but there have been instances of ALPRs being widely inaccurate. A 2019 estimate found that the "accuracy rate of the license plate readers is about 90%," per KTVU-TV — but this means that one in 10 plates are misread. This is "especially concerning, considering that the cameras can scan 2,000 plates per minute," according to the partisan think tank Independent Institute. As a result of this error rate, "mistakes and misidentifications are frequent." In one instance from 2009, a San Francisco woman was pulled over at gunpoint after ALPRs mistakenly identified her car as stolen. 

Pro: It has other uses 

Beyond assisting in the capture of criminals, ALPRs can also be used for traffic safety. This includes speed traps and red-light monitoring as well as parking enforcement, according to ALPR manufacturer Tattile. Other groups can also use ALPRs to their advantage. Public transit agencies use the tech to "collect highway tolls, reducing traffic bottlenecks caused by tollbooths," law firm Lane Powell reported. Property managers and homeowners associations can use ALPRs to "track vendor's, visitor's, or tenant's activities, enforce parking restrictions and investigate insurance claims," the firm added. 

Con: It can be abused

The use of ALPRs is "almost entirely unregulated and can be subject to abuse," according to a report from the University of Michigan. This is especially true at the federal level, which has no guidelines for ALPR usage. As a result, "law enforcement and private actors can use the technology however they wish," the report added. There have also been reported instances of police officers using data collected from ALPRs to "get information on romantic partners, business associates, neighbors, journalists and others for reasons that have nothing to do with daily police work," the report said. 

Pro: It strengthens security

Given that ALPRs are often used to watch neighborhoods, many police departments tout them as tools to enhance community security. Flock Safety, an ALPR manufacturer, claims to have "reduced crime in their cities' markets by 70% and have made more than 2,500 communities safer," the Pensacola News Journal reported. Flock allows communities to receive a consistent stream of data about neighborhood crimes, including burglary, home theft, vandalism and mail theft, according to its website. Similar ALPRs are already available on the market. 

Con: It creates legal questions

Many civil rights groups have cautioned the widespread use of ALPRs as a potential violation of privacy. ALPRs collect and store data on the cars they scan, and this data is "sometimes pooled into regional sharing systems," the American Civil Liberties Union (ACLU) reported. As a result, "enormous databases of innocent motorists' location information are growing rapidly," the ACLU added, and this information is often kept for years "with few or no restrictions to protect privacy rights." In the aftermath of Roe v. Wade being overturned, there are also concerns that state governments could use ALPRs to "track people trying to cross state lines" to get an abortion, Wired reported.