The Supreme Court on Monday ruled unanimously that the police violated the Constitution when they placed a Global Positioning System tracking device on a suspect’s car and monitored its movements for 28 days.

The case concerned Antoine Jones, who was the owner of a Washington nightclub when the police came to suspect him of being part of a cocaine-selling operation. They placed a tracking device on his Jeep Grand Cherokee without a valid warrant, tracked his movements for a month, and used the evidence they gathered to convict him of conspiring to sell cocaine.

"The Government physically occupied private property for the purpose of obtaining information. We have no doubt that such a physical intrusion would have beenconsidered a 'search' within the meaning of the FourthAmendment when it was adopted," Justice Antonin Scalia wrote in his majority opinion joined by John G. Roberts Jr., Anthony M. Kennedy, Clarence Thomas, and Sonia Sotomayor.

In this case, "the Government usurped Jones’ property for the purpose of conducting surveillance on him, thereby invading privacy interests long afforded, and undoubtedly entitled to, Fourth Amendment protection," wrote Justice Sotomayor in her concurring opinion.

While concurring in judgement, Justice Alito cautioned that the ruling must take into account modern technology and its challenges. "This case requires us to apply the Fourth Amendment’s prohibition of unreasonable searches and seizures to a 21st-century surveillance technique," he wrote.

"I agree that 'we must assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.’ But it is almost impossible to think of late- 18th-century situations that are analogous to what took place in this case," he added.

The Supreme Court's verdict will place a burden on widely used law enforcement surveillance techniques, however authorities remain free to seek warrants from judges authorizing the surveillance.

Sources: Supreme Court opinion in United States v. Jones
The New York Times