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Police photos of your license plates and the Fourth Amendment

July 19, 2013 by Scott Bomboy


Can the police really take photos of your car's license plates and store them for years in a database? A new report from the American Civil Liberties Union is sparking a broader debate about the idea, which has potential Fourth Amendment ramifications.

800px-Surveillance_equipment_5413On Wednesday, the ACLU published the results of a year-long project to analyze 26,000 pages of data, obtained from Freedom of Information Act requests in 38 states and Washington, D.C., that show how the police use and store license-plate data gathered from public stationary cameras.

“As is often the case with surveillance technology, there are unobjectionable – even beneficial – uses of license plate readers. We don’t object when they’re used to identify people who are driving stolen cars or are subject to an arrest warrant. But they should not become tools for tracking where each of us has driven,” said ACLU Staff Attorney Catherine Crump.

Crump and the ACLU are concerned about how all those pictures of license plates, and the data that accompanies them, are being stored.

“But increasingly, all of this data is being fed into massive databases that contain the location information of many millions of innocent Americans stretching back for months or even years,” Crump says in a blog post introducing the report.

“As it becomes increasingly clear that ours is an era of mass surveillance facilitated by ever cheaper and more powerful computing technology (think about the NSA's call logging program), it is critical we learn how this technology is being used. License plate readers are just one example of a disturbing phenomenon: the government is increasingly using new technology to collect information about all of us, all the time, and to store it forever – providing a complete record of our lives for it to access at will,” she says.

The Fourth Amendment, and its interpretation by the courts, determines how police and law enforcement investigators can gather information provided by automatic license plate readers, or ALPRs.

“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized,” the amendment reads.

The conventional wisdom is that it's OK for police to snap photos of your car and its license plates, because there isn’t an expectation of privacy for drivers who display public vehicle registration information while using public roadways. (This “test” was established in the Supreme Court case of Katz v. United States.)

A Congressional Research Service report from April 2013 on privacy concerns said that, “a majority of the reviewing federal circuit courts have held that a person has no reasonable expectation of privacy in his license plate number. However, it appears that no federal court has addressed the constitutionality of the use of ALPRs … as opposed to plate numbers collected by a human observer.”

A separate research report, prepared for the Justice Department by the International Association of Chiefs of Police, raises issues similar to those voiced by the ACLU.

“Although there may be no reasonable expectation of privacy in any particular sighting of a vehicle traveling on a public roadway, the systematic capture, storage, and retrieval of ALPR data may nevertheless raise important privacy concerns,” the report says.

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One big concern expressed by the ACLU is that the massive gathering of license-plate data only resulted in direct police action in rare cases.

“The vast majority of license plate data are collected from people who have done nothing wrong at all. Often, only a fraction of 1 percent of reads are hits — and an even smaller fraction result in an arrest,” it said.

And the technology itself may not be foolproof. In an August 2012 story, a reporter for Ars Technica rode along with police in a northern California to see how the license plate reading technology worked, and it seemed to work very well in most cases.

“However, the system is not without flaws. It tends to yield numerous false positives because the hot list data received from the California Department of Motor Vehicles takes a long time to be updated—and because the system cannot distinguish out-of-state plates,” said Cyrus Farivar.

Farivar also pointed to research at George Mason University about the public perception of license-plate readers.

“[The] majority of respondents considered the data collected by [license-plate reader] systems to be private, and that policies and protections should be in place for the use of this data,” the study said.

And then there is a recent Supreme Court case, United States v. Jones, which involved the use of a GPS device planted by authorities to track the movement of a car. While the Court decided that actual act of placing of the hidden device on the car was a Fourth Amendment violation, there were also hints that the Court could consider, at a late date, the legality of using a GPS device to track the car’s movements for a long time period.

Justice Samuel Alito and three other Justices said in a concurring opinion that, “the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy. For such offenses, society’s expectation has been that law enforcement agents and others would not—and indeed, in the main, simply could not—secretly monitor and catalog every single movement of an individual’s car for a very long period.”

A fifth Justice, Sonia Sotomayor, had even stronger thoughts on the practice of storing long-term personal geographical data.

Sotomayor asked "whether people reasonably expect that their movements will be recorded and aggregated in a manner that enables the Government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on.”

Scott Bomboy is the editor-in-chief of the National Constitution Center.

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