Supreme Court: Getting Cell Phone Location History is a Fourth Amendment Search

Sometimes it feels good to be right.

We’ve been saying for years that if an investigator tells you he’s got “contacts” at the phone company that can “ping” someone’s cell phone to find out where they are and where they’ve been, run in the other direction. We were vindicated in 2018 when the Court decided in Carpenter v. U.S. (585 U.S. 296) geolocation “phone pinging” of phone’s current location was a Fourth Amendment search.

Yesterday, the Supreme Court held (with votes from both the “liberal” and “conservative” sides of the bench), that police officers had conducted a Fourth Amendment search when they obtained a person’s location history from Google “because an individual has a reasonable expectation of privacy in his cell-phone location information.”

This is known as geofencing. You have no suspects, so you find out who’s been in the area of the crime by looking at phone locations. That doesn’t mean that all such searches are unreasonable, only that a court should have been asked to allow it, just like when police seek a warrant to search your home.

Some of the justices likened the history of where you’ve been to the personal papers protected by the Fourth Amendment.

All this means that an investigator deciding to call his buddy up to do the searching and spill a phone’s location history is not allowed.

I’m pleased to say that this is the issue we flagged here in 2012: Ping a Cell Phone, Cross a Line, when we pointed out that whether pinging was a Fourth Amendment search was already a live issue in some federal circuit courts. And even if it had been an allowed practice, we mentioned that some investigators resort to fraud in order to trick phone users into divulging their locations.

Today there is no doubt. Wherever you are in the United States, you have an expectation of privacy as to the location data on your phone – current and historical. Handing it over to Google doesn’t mean you agree to hand it over to the police.

If the police want it, they can ask a court for permission. If the court says the search in reasonable, it will allow it with a warrant.

Some investigators want to behave as if they are spies or law enforcement. My advice to them: if you want to be a spy and break a lot of rules overseas, be a spy. If you want to work for law enforcement, do that.

Otherwise, follow the rules.