A federal appeals court in Pennsylvania ruled this week that probable cause – and a warrant – are required before using GPS tracking on a suspect’s vehicle. The ruling provides important context to a Supreme Court ruling early last year in which the justices unanimously found that GPS tracking is not, as argued by law enforcement and government officials, simply another form of traditional surveillance.

The Supreme Court’s decision in January 2012 reversed the conviction of alleged drug lord Antoine Jones. Police used a GPS tracker to log Jones’ movements for a month while building a case against him. He was initially sentenced to life in prison.

Robert Barnes quotes Justice Scalia’s majority opinion, in which the court said, “We hold that the government’s installation of a GPS device on a target’s vehicle, and its use of that device to monitor the vehicle’s movements, constitutes a ‘search,'” and therefore, under the protections of the Fourth Amendment regarding search and seizure, a warrant is required.

Andrea Peterson, writing for the Washington Post on this week’s Philadelphia appeals court ruling, explains that the more recent case involved a string of pharmacy burglaries across three states. Police suspected three brothers and “slapped a magnetic GPS unit to one of their vehicles after consulting the U.S. Attorney’s office – but without obtaining a warrant.” After tracking the vehicle to a recently burglarized pharmacy, police stopped and searched the brothers, finding stolen items. The defense argued that the evidence thus obtained was gathered through an illegal search.

“The District Court agreed with the brothers,” writes Peterson, “and the government appealed the case to the Court of Appeals for the 3rd District. On Tuesday, a three-judge panel upheld the lower court’s ruling, finding that the actions of the police were ‘highly disconcerting’ under a physical intrusion theory of the Fourth Amendment. The judges dismissed the government’s arguments that the search was legal because the police had probable cause even if they didn’t seek a warrant, saying, ‘generally speaking, a warrantless search is not rendered reasonable merely because probable cause existed that would have justified the issuance of a warrant.'”

In other words, it isn’t enough to think a suspect is dirty; it isn’t enough to find evidence, subsequently, that you were right about that suspect; if you are a law enforcement officer in the United States, it is still necessary to obtain a warrant before applying a GPS tracking device to a suspect’s vehicle. In a culture increasingly inundated with public surveillance in the form of traffic cameras, security cameras, facial recognition software and any number of other tracking methods, your movements, your transactions and your interests are constantly being cataloged and indexed. What most of us do not seem to understand, however, is that our movements are being tracked by a device we have voluntarily chosen to put in our pockets or on our belts. That device is your smartphone.

Last week in Salon, Anthony Townsend highlighted this issue. “It starts in our pockets,” he writes. “Mobile devices, like the iPhone, keep a running record of where we’ve been. … Most phones allow you to turn off location tracking, but mobile devices can also be used to track us passively, without our knowledge or consent, through systems that monitor the unique wireless beacons phones send out as they communicate with nearby towers. … By triangulating the beacons sent by our phones to nearby cell towers, our location can be pinpointed with an accuracy of ‘a few meters’ (the company doesn’t publicly specify beyond that), enough to know how you move from store to store, your ‘dwell time’ spent inside, the sequence of shops visited, and even movements between sections inside large department stores.”

Controversy over data of this type has already come to the public’s attention in the form of debate over whether stores and shopping malls may use your phone to gather data on consumer traffic and shopping habits. Just this week, a New Jersey court ruled that your cell phone location enjoys constitutional protection at the state level. “The Fourth Amendment of the U.S. Constitution guarantees ‘[t]he right of the people to be secure in their persons, house, papers, and effects, against unreasonable searches and seizures,'” write Annabelle Steinhacker and Rubin Sinins. “… From this vantage point, the U.S. Supreme Court has [previously held] that, under federal law, using an electronic device to infer facts about the inside of a location impedes on constitutionally protected privacy interests and constitutes an unreasonable search without a warrant.”

Steinhacker and Sinins go on to comment on the recent New Jersey ruling, which holds that, at least in that state and according to its constitution, “an individual’s privacy interest in the location of his or her cell phone” is protected under law. “Law enforcement must, therefore, either obtain a warrant upon a showing of probable cause prior to initiating a cell phone trace or qualify for an exception to the warrant requirement.”

But while we all seem unsettled by the degree of tracking possible through our phones and other GPS-enabled devices – a tiny solar GPS unit is now available that can track anything to which you affix it – we are simultaneously self-tracking through social media. We “check in” at sites like Foursquare that in turn post links to Facebook. We tweet our moment-to-moment activities to our friends and family. We obsessively photograph everywhere we go and put these photographs online. Our social media activities can be cross-indexed to form a de facto, entirely self-adopted surveillance sketch of our daily lives.

Until we stop sewing GPS trackers into our children’s clothes, until we stop telling the Internet everywhere we go and everything we do when we get there, we are voluntary participants in the culture of total surveillance. We are facilitating the process whereby an increasingly invasive government feels entitled to know everything about us. We will, therefore, have no one to blame but ourselves when our elected masters decide that citizens’ feelings on the matter are no longer relevant.

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