A recent U.S. Supreme Court decision has held that police must obtain a warrant before tracking your movements through cell phone signals.

Each time your phone connects to a cell site, it leaves a trace in the form of a time-stamped record. Based on these records, police can track where you’ve been. Writing for the majority in Carpenter v. United States, Justice Roberts observed that such cell site location information (CSLI) is “detailed, encyclopedic and effortlessly compiled.”

The court analogized CSLIs to GPS monitoring which is also protected by the Fourth Amendment. The court rejected the argument that CSLIs are like telephone numbers and bank records which are held by third parties and thus do not require a warrant.

Justice Roberts wrote: “Given the unique nature of cell phone location records, the fact that the information is held by a third party does not by itself overcome the user’s claim to Fourth Amendment protection. Whether the Government employs its own surveillance technology … or leverages the technology of a wireless carrier, we hold that an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through CSLI.

If you have been charged with a crime, contact an experienced criminal law attorney immediately. An attorney can review your case for its best possible defense. Did the police collect evidence without a required search warrant? If so, an attorney may be able to petition the court to suppress any evidence that was improperly obtained.

If you have questions about this or another related Illinois criminal or traffic matter, please contact Matt Keenan at 847-568-0160 or email

(Besides Skokie, Matt Keenan also serves the communities of Arlington Heights, Chicago, Deerfield, Des Plaines, Evanston, Glenview, Morton Grove, Mount Prospect, Niles, Northbrook, Park Ridge, Rolling Meadows, Wilmette and Winnetka.)

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