Today, Supreme Court justices unanimously placed restrictions on Police use of GPS tracking devices in the case United States v. Antoine Jones, No. 10-1259. The use of such devices is now considered a 'search' and requires a warrant under the Fourth Amendment.

The American Civil Liberties Union Legal Director Steven R. Shapiro stated, “Today's decision is an important victory for privacy. While this case turned on the fact that the government physically placed a GPS device on the defendant's car, the implications are much broader. A majority of the Court acknowledged that advancing technology, like cell phone tracking, gives the government unprecedented ability to collect, store and analyze an enormous amount of information about our private lives. Today's decision suggests that the court is prepared to address that problem. Congress needs to address the problem as well.”

Reuters reported on the case today:

The Supreme Court for the first time ruled on Monday that police attachment of a GPS device to monitor a suspect's vehicle was a search protected by constitutional privacy rights, a test case involving new surveillance technology.

The high court's ruling was a defeat for the Obama administration, which defended the use of global positioning system devices without a warrant and without a person's knowledge as a legal way to monitor a vehicle on public streets.

The justices upheld a precedent-setting ruling by an appeals court that the police must first obtain a warrant to use a GPS device for an extended period of time to covertly follow a suspect.

The Hill writes:

The case, United States v. Jones, involved a Washington, D.C., nightclub owner, Antoine Jones, who was suspected of trafficking cocaine. Police placed a GPS device on the underside of Jones's Jeep Cherokee and followed his movements for more than four weeks.

In the ruling, [Associate Justice Antonin] Scalia wrote that GPS tracking would have been considered a search when the Fourth Amendment was adopted.

"It is important to be clear about what occurred in this case: The government physically occupied private property for the purpose of obtaining information," Scalia wrote. "We have no doubt that such a physical intrusion would have been considered a 'search' within the meaning of the Fourth Amendment when it was adopted."

Politico adds:

In 2004, the FBI and D.C. police began investigating Jones, a night club owner, for trafficking narcotics. Authorities applied in 2005, before a D.C. court, to track the car owned by Jones’s wife. According to the court, the warrant was issued with a 10-day time horizon.

But authorities did not install it until the 11th day, and they did it outside of Washington, D.C. They ultimately tracked Jones’s movements for 28 days, collecting evidence that led to a number of charges on possession and more. With Jones facing a life sentence, a legal battle ensued over whether the GPS evidence was admissible in those proceedings. The Supreme Court took the case last year.

In arguments, the government contended that vehicles traveling on public roads lack a reasonable expectation of privacy, relying on a 1983 case involving the placement of a so-called beeper in a container that police tracked. But the argument was met with skepticism before the court, which noted the great advances in location tracking technology in over two decades.