Since the terrorist attacks of September 11, 2001, on the World Trade Center and the Pentagon, Americans have been forced to live with the reality that the assumption of personal privacy no longer exist in the United States. In the name of constant vigilance, more and more intrusions into what was once considered “personal space” are occurring. While many of these efforts have been made public, even more are happening outside the public’s consciousness.

This is troubling, as most of the information gathered by intelligence agencies is not immediately actionable. Most of the individuals profiled did nothing wrong and are not considered suspects in any criminal action. Typically, this information sits in various databases indefinitely, and — when combined with information from other databases — can create a nearly complete, publicly accessible record of a person’s life.

The American Civil Liberties Union recently challenged such a collection attempt. In a report released on Tuesday, the ACLU discusses the proliferation of automatic license plate readers — devices that are usually attached to a law enforcement vehicle and designed to automatically scan and record license plates as cars pass by. Designed to scan for hits against a “hot list,” or a dynamic listing of actively sought vehicles, this technology can make “be on the lookout” calls and search missions easier and less-labor intensive.

However, these systems store the license plate information not only of hits, but of every vehicle they scan. In addition, many of these systems hold on to this data indefinitely. That means the system builds a record that can record a person’s location at a given time. This may seem trivial on cursory inspection, but in reality, it has grave consequences.

Warrantless tracking

The debate over warrantless geopositioning has been argued before. The 2012 case of United States v. Jones dealt with an incident in which the FBI and District of Columbia police planted a GPS beacon on the car of nightclub owner Antoine Jones, who was suspected of narcotics trafficking. The U.S. Court of Appeals for the District of Columbia Circuit ruled that geolocation tracking is a search covered by the Fourth Amendment.

“Prolonged surveillance reveals types of information not revealed by short-term surveillance, such as what a person does repeatedly, what he does not do, and what he does ensemble,” the court ruled.

“These types of information can each reveal more about a person than does any individual trip viewed in isolation. Repeated visits to a church, a gym, a bar, or a bookie tell a story not told by any single visit, as does one‘s not visiting any of these places over the course of a month. The sequence of a person‘s movements can reveal still more; a single trip to a gynecologist‘s office tells little about a woman, but that trip followed a few weeks later by a visit to a baby supply store tells a different story. A person who knows all of another‘s travels can deduce whether he is a weekly church goer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups — and not just one such fact about a person, but all such facts.”

The government used Jones’ movements as their primary evidence in securing a conviction against him. This plays into the intelligence community’s “mosaic theory,” which states that a single event may seem irrelevant, but combined with many other similar events and facts, a pattern may form that points to something significant. Privacy advocates are most troubled by the government’s habit of holding the information indefinitely, as it suggests a willingness by the government to “peek” into personal space, store what it finds, and continuously cross-index these databases in hope of finding and stopping a few, despite the discomfort of many.

In July 2012, the ACLU filed public records requests for almost 600 local and state police departments in 38 states in order to chart the use of automatic license plate readers, which many law enforcement agencies received through federal funding. About half responded. Some of the revelations revealed in the ACLU’s review is that Milpitas, Calif. — which has a population of 67,000 and no formal policy on how long personal data should remain in their database — had more than 4.7 million plate reads as of August 2012. Grapevine, Texas, has a population of 47,000 and more than 2 million plate reads in its database.

Meanwhile, in Minnesota…

However, one of the most interesting revelations came from Minnesota. The Minnesota State Patrol, which serves a population of 5.3 million residents, has used automatic license plate readers since 2008, mostly in the Twin Cities of Minneapolis and St. Paul. Until August 2012, there were no state rules on how the data should be stored or used. Minneapolis held on to its data for a year. St. Paul discarded its recorded plate information after 14 days. The State Patrol purged its records every 48 hours. However, the information was public, so anyone could request it, download it, and store it forever.

This all changed, however, after the Star Tribune newspaper successfully requested the automatic license plate reader information for Minneapolis Mayor R.T. Rybak’s city-issued car and published a map showing everywhere the mayor was spotted using the plate readers.

Since this happened, there has been a call to limit the use of the scanners.

“This is something that I think demands attention on a statewide basis,” said state Rep. Tony Cornish (R-Good Thunder), chairman of the House Public Safety Committee.

“In some cases, the license plate data the police have retained have proven helpful in investigating and solving crimes,” Rybak said in a statement. “But there are important, legitimate concerns around the length of time it is stored and how it is or can be used or accessed that we need to address.”

Protecting personal information

The public accessibility of this information and its use for non-law enforcement reasons have proven to be problematic. Advertising and marketing firms regularly make use of the information. In Minneapolis, there have been public access requests from private companies — such as car repossessors, bondsmen and companies seeking to track down stolen or damaged goods. By most measures, this could be considered an invasion of privacy.

There is nothing inherently wrong with law enforcement monitoring cars. They have done this for decades with speed detectors. But in collecting information, it is highly important to treat it with respect. The ACLU has proposed recommendations that license plate reader data should be made available only to law enforcement, that the data should be made private, that license plate reader users must publicly disclose the fact that they use the device, and that individuals should have the right to know if they have ever been recorded by one of these scanners.

The Supreme Court has ruled that one has the right to privacy if there is a personal assumption of privacy and society can recognize that assumption as being reasonable. In everyday life, most people consider their movements to be personal. It is the duty of government to accept this while still maintaining the peace.

“In our society, it is a core principle that the government does not invade people’s privacy and collect information about citizens’ innocent activities just in case they do something wrong,” the ACLU wrote. “Clear regulations must be put in place to keep the government from tracking our movements on a massive scale.”