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While GPS technology has gained favor with American consumers by providing precise driving directions, the lack of specific instructions in a recent Supreme Court opinion has experts disagreeing over whether police are now required to obtain a warrant before affixing a GPS-tracking device to a suspect's car.

The Supreme Court made front-page headlines when it ruled in the case United States v. Jones last week that police attachments of GPS-tracking devices to automobiles are considered searches under the Fourth Amendment.

In the case, prosecutors obtained a drug trafficking conspiracy conviction for a Washington D.C., nightclub owner by using evidence obtained from a GPS-tracking device installed on his Jeep after a warrant expired. Authorities had tracked his movements for nearly a month.

On appeal, the D.C. Court of Appeals threw out the evidence from the GPS device and reversed the conviction. The Supreme Court affirmed the D.C. Circuit's ruling last week.

Most media reports of the Supreme Court's decision said the court was requiring police to obtain warrants for attaching GPS devices.

But several experts argued that the court had not in fact ruled that a warrant is now required.

"The court merely held that the installation of the GPS was a Fourth Amendment 'search,'" George Washington University Professor of Law and computer law expert Orin Kerr wrote on The Volokh Conspiracy website.

"The court declined to reach when the installation of the device is reasonable or unreasonable. So we actually don't yet know if a warrant is required to install a GPS device; we just know that the installation of the device is a Fourth Amendment 'search.'"

But other experts have said the court did create a warrant requirement for installing GPS devices. They point to past Supreme Court rulings that held that all Fourth Amendment searches require warrants unless the police action meets a specific and well-delineated exception.

These scholars say that because the court did not create an exception for GPS searches, those intrusions therefore require a warrant.

"Orin Kerr would probably not say that you don't need a warrant to break down the door of someone's house," Priscilla Smith, who is a senior fellow at the Yale Law School Information Society Project, told NewsCore. "He would say you do need one unless one of the exceptions apply. Same is true here."

Other scholars had views that fell somewhere in between those of Kerr and Smith.

University of Iowa Law School Professor of Law James Tomkovicz told NewsCore that the Supreme Court "dodged" the warrant issue, but said it would be very difficult to persuade courts in the future that police do not need warrants to install GPS devices on automobiles.

"It would be pretty unprecedented for the court to call it a search and then turn around and say you don't need a warrant or you don't even need probable cause," Tomkovicz said.

Lawrence Muir, who teaches a cybercrimes seminar as an adjunct professor at Washington and Lee University School of Law, said that police are now generally required to obtain warrants for GPS attachments after Monday's decision.

But because the majority of justices based their reasoning on property rights, police could use GPS technology to track stolen property without a warrant.

"If OnStar is already tracking a stolen vehicle, I think the police can use that," Muir told NewsCore.

OnStar is a GPS-based service that allows drivers to audibly communicate from their cars with OnStar representatives for emergency services and directions.

With so much disagreement among experts in the field, where are police expected to turn for an answer to the warrant question?

Ronald Wright, professor of law at Wake Forest University School of Law, said there would be no conclusive answer until the Supreme Court decided a series of cases on GPS and technology-driven government searches.

"You never know the meaning of just one case," Wright told NewsCore, alluding to a famous quotation by 20th century legal scholar Karl Llewellyn. "Just looking at this case standing alone, we won't know what it means until it's followed by a series of cases."

Wright said the Jones decision was the beginning of a long-term debate on the court over the framework in which it will analyze technology-driven searches.

While the court voted 9-0 in United States v. Jones in holding that the GPS attachment was a search, the court split 5-4 on its reasoning.

Five justices joined an opinion by Antonin Scalia that ruled the GPS attachment was a search because the government physically intruded on private property. The other four justices latched on to an opinion by Samuel Alito that based its analysis on "reasonable expectations of privacy."

Wright said he expects the high court in the coming years to take on more technology-based search cases and issue decisions that will give better guidance to police on which types of searches are constitutionally permissible.

Muir said that much of the problem may be solved in state legislatures as states define for themselves the limits on police use of technology to track criminals.

Wright said in the meantime, police would be best served in being cautious with GPS searches.

"If I were advising the police, I'd say, yeah, you need to get a warrant," Wright said.