The President Barack Obama administration is claiming that authorities do not need court warrants to affix GPS devices to vehicles to monitor their every move.

The administration maintains that position despite the Supreme Court's infamous decision last year that concluded that attaching the GPS devices amounted to search protected by the Constitution.

The administration is set to make its argument Tuesday before a federal appeals court in a case testing the parameters of the high court's 2012 decision. If the government prevails, the high court's ruling would be virtually meaningless.

"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, an attorney with the American Civil Liberties Union, said in a telephone interview.

Crump will square off on the issue Tuesday with the Obama administration before the 3rd U.S. Circuit Court of Appeals in Philadelphia.

The question of whether probable-cause warrants issued by a judge are needed is an open one because the high court stopped short of answering it. The court ruled in January, 2012, that attaching the device amounted to a constitutionally protected search because it was a trespass on a private vehicle.

Even so, in the decision's aftermath the government disabled 3,000 GPS trackers it had installed on vehicles without warrants.

Among other things, the government is arguing that the Supreme Court has given the police broad exemptions to obtaining search warrants, such as with the oversight of school students and probationers, maintenance at the border, and even searching vehicles and luggage for drugs. That exception should apply to GPS devices, the government said.

In court papers, the authorities also told the 3rd Circuit that demanding warrants could even hinder terrorism cases: (.pdf)

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. 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.

The case concerns three brothers, Harry Katzin, Michael Katzin and Mark Katzin – indicted on allegations of robbing a Philadelphia-area pharmacy. The authorities suspected they were behind a string of late-night pharmacy heists, and attached the device to a Dodge Caravan they believed was used in the robberies. The police did not have a warrant.

Shortly after a 2010 Rite Aid heist, officers tracked the Dodge Caravan and arrested the brothers. Inside the vehicle, they discovered the pharmacy's surveillance system and drugs in the vehicle that was monitored for 48 hours with a GPS device.

After the Supreme Court's GPS ruling, a federal judge tossed the evidence, saying a warrant was required (.pdf) to put the GPS device on the Dodge Caravan.

"This Court, however, in the final analysis, has not been persuaded that the GPS monitoring that occurred in this case is factually analogous to any existing exceptions to the warrant requirement, or merits a new exception for Fourth Amendment warrantless search or seizure law," U.S. District Judge Gene E. K. Pratter of Pennsylvania ruled in May.

The government appealed.