Warrantless cell-phone tracking widespread, study finds

Many U.S. police departments are tracking the location of cell phones without a warrant or court supervision, according to an investigation by the American Civil Liberties Union.

Starting last summer, ACLU affiliates around the country began filing hundreds of Freedom of Information Act requests with law enforcement agencies to find out about their policies and procedures governing cell-phone location tracking.

Many agencies didn't respond at all. But based on more than 5,500 pages of documents from the 200 agencies that did respond, the ACLU found that although police departments routinely use cell-phone location tracking in their investigations, "only a tiny minority reported consistently obtaining a warrant and demonstrating probable cause to do so."


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Certain uses of the tracking summarized in a New York Times story on the practice raise constitutional questions, the ACLU said:

  • Some police departments in states such as Nevada and Colorado are tracking cell signals back to towers in non-emergency investigations.
  • State prosecutors in California told local police departments how to get wireless carriers to download text messages from "cloned" telephones, even when they are turned off.
  • Police in Lincoln, Neb., collect Global Positioning System location data on cell phones, which provides even more specific information on a cell user's whereabouts than cell tower location, without demonstrating probable cause.
  • The police department in Tucson, Ariz., sometimes engages in a practice known as a "tower dump," obtaining the phone numbers of all cell users in a specific location at a particular time.

The relative lack of judicial oversight in these investigations has received special scrutiny from civil libertarians in light of the Supreme Court's recent ruling in U.S. vs. Jones. In that case, the court ruled that prolonged government use of a GPS tracking device is a "search" within the meaning of the Fourth Amendment's ban on "unreasonable search and seizure."

The government had argued that the tracking was not much different than following someone by sight, but the court ruled that installing a GPS device to collect data went beyond surveillance and constituted a search, which would require a warrant to carry out.

"The conclusion should be no different when the government tracks people through their cell phones, and in both cases a warrant and probable cause should be required," the ACLU said.

About the Author

Donald White is an assistant managing editor with 1105 Government Information Group.

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