Lawyers for the Obama administration will argue next week that US authorities are not required to obtain a search warrant before attaching a GPS device to an individual’s car in order to keep tabs on them.

The case, set to be heard on Tuesday by the 3rd US Circuit Court of Appeals in Philadelphia, comes over a year after a US Supreme Court decision failed to convince the Department of Justice that warrantless GPS tracking is an infringement on Americans' Constitutional rights.

“This case is the government’s primary hope that it does not need a judge’s approval to attach a GPS device to a car,” Catherine Crump, a lawyer with the American Civil Liberties Union (ACLU) told Wired magazine.

In January 2012 the Supreme Court overruled an Obama administration assertion that police should be permitted to affix a GPS device to a personal vehicle without a search warrant. Questions were left, however, when the Court declined to answer whether that type of search was unreasonable and when justices could not reach a consensus on how police would need to monitor a suspect before requesting a warrant.

“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 movement, constitutes a ‘search,’” Justice Antonin Scalia wrote for the five-justice majority last January.

Scalia stipulated in the opinion that a warrant was not always necessary, but failed to mention any specific examples of when this would be the case.

Now prosecutors are honing on Scalia’s exact language, arguing that the Supreme Court’s decision only specifies that the installation of a GPS constitutes a search, while the tracking that follows does not. The government argues that the Supreme Court has given police near free reign in allowing for search warrant exceptions.

Searches of students, individuals on probation and border crossings are among the proposed exceptions.

The argument resurfaced after Philadelphia brothers Harry, Michael and Mark Katzin were indicted for a string of late-night pharmacy burglaries in 2010. Suspicious of the Dodge Caravan they thought was used in the robberies, investigators monitored the vehicle with a GPS device for 48 hours and were able to trace the brothers' involvement.

Arguing in US v. Katzin, government prosecutors claimed that a law requiring them to seek a warrant would seriously impede investigations of terrorist suspects.

“Requiring a warrant and probable cause before officers may attach a GPS device to a vehicle, which is inherently mobile and may no longer be at the location observed when the warrant is obtained, would seriously impede the government’s ability to investigate drug trafficking, terrorism and other crimes,” authorities said in court.

“Law enforcement officers could not use GPS devices to gather information to establish probable cause, which is often the most productive use of such devices. Thus, the balancing of law enforcement interests with the minimally intrusive nature of GPS installation and monitoring makes clear that a showing of reasonable suspicion suffices to permit use of a ‘slap-on’ device like that used in this case.”

While the ACLU accused the government of prosecutorial overreach in the case, it praised a new bill - the so-called 'GPS Act' - that would require law enforcement to get a warrant in order to access an individual’s GPS tracking history, whether it be from a vehicle device or a cell phone provider. The bill, which would not affect emergency services but would require police to prove probable cause, was reintroduced into Congress by Senators Ron Wyden (D-OR), Mike Kirk (R-IL) and Representative Jason Chaffetz (R-UT).

In a statement, Wyden decried the government’s blind eye to police overreach.

GPS technology has evolved into a useful commercial and law enforcement tool - but the rules for the use of that tool have not evolved with it,” he said. “The GPS Act provides law enforcement with a clear mandate for when to obtain a warrant for the geolocation information of an American…It protects the privacy and civil liberty of any American using a GPS-enabled device."

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