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Earlier this year, the Supreme Court said police had overstepped when they planted a GPS tracker on a suspected drug dealer's car without getting any search warrant. It is another in a long line of cases testing the balance between personal privacy versus the needs of law enforcement. The decision set off alarm bells inside the FBI, where officials are trying to figure out whether they need to change the way they do business. NPR's Carrie Johnson has the report.
CARRIE JOHNSON, BYLINE: Before the Supreme Court ruling in January, the FBI had 3,000 GPS tracking devices in the field. Just in case, government lawyers scrambled to get search warrants for weeks before the decision, working to convince judges they had probable cause to believe crimes were taking place. But after the ruling, agents still had to turn off 250 devices that they couldn't turn back on.
FBI director Robert Mueller told Congress the ruling will change the way agents work.
ROBERT MUELLER: It will inhibit our ability to use this in a number of surveillances where it has been tremendously beneficial. We have a number of people in the United States whom we could not indict; there's not probable cause to indict them or to arrest them, who present a threat of terrorism – articulated, maybe up on the Internet, may have purchased a gun, but have taken no particular steps to take a terrorist act.
JOHNSON: Before the high court decision, the FBI would have deployed electronic trackers to monitor those people. Now teams of six or eight agents have to watch them, taxing the agency's resources.
Andrew Weissmann is the top lawyer at the FBI. He says the Supreme Court made a distinction about the Fourth Amendment, which guards against unreasonable searches and seizures - ruling that computers that follow suspects are much more intrusive than people doing the same thing.
ANDREW WEISSMANN: The court essentially is saying that you have an expectation of privacy even though if it was done by humans, there would be no violation. But because it's done by machines, it is.
JOHNSON: In the Supreme Court case, FBI agents investigating drug crimes secretly put a GPS tracker on a Jeep belonging to Antoine Jones. They kept it there for weeks without getting approval from a judge.
Catherine Crump works at the American Civil Liberties Union.
CATHERINE CRUMP: In the Jones case, the Supreme Court held that reasonable people do not expect the government to track their location by attaching a GPS device to the bottom of the car for, in that case, 28 days.
JOHNSON: The full implications of the decision are still coming into focus. Weissmann says he's telling FBI agents...
WEISSMANN: When in doubt to obtain a warrant, to protect your investigation.
JOHNSON: But he says that's not always possible.
WEISSMANN: And the problem with that is that a search warrant requires probable cause to be shown, and many of these techniques are things that you use in order to establish probable cause.
JOHNSON: Government lawyers say the Supreme Court decision reaches well beyond electronic trackers.
Solicitor General Don Verrilli put it this way at a recent Georgetown University conference.
DON VERRILLI: That decision is reverberating very quickly into areas that I'm sure lots of you care about - national security, cyber security, privacy more generally.
JOHNSON: The Justice Department's predicting new fights over cars that come with GPS already installed and cameras the FBI sticks on poles to catch drug dealers and speeders. Then there's the big enchilada - cell phone information.
The U.S. Court of Appeals for the Fifth Circuit will hear a case this year about whether the government can get access to cell phone location information without a warrant.
You might be surprised to know it, but every eight seconds or so, your cell phone can transmit information to a local cell tower signaling where you are. Crump, of the ACLU, says that's a lot more intrusive than putting a tracker on someone's car.
CRUMP: After all, a cell phone is something you carry with you wherever you go.
JOHNSON: As for Antoine Jones, whose case made Supreme Court history, prosecutors say they'll try him again, maybe using some of the location information from his cell phone.
Carrie Johnson, NPR News, Washington.