Cell phone forensics and personal privacy - Supreme Court Case
- rich4285
- 10 hours ago
- 2 min read
The Supreme Court of the US is taking a crack at the privacy of your cell phone's location data. They must decide whether geofence warrants are unconstitutional or not.
A geofence warrant is issued by law enforcement and if signed by a judge forces a company such as Google to provide location data of all the cell phone users within a specified geographic area and a specified time window. This is typically within an hour or two of a crime and several hundred meters around the crime location.
The following map shows the area of the geofence within the red circle.
This may seem like a reasonable request and such a small area but as the following map shows there are several businesses within and near the circle.
The case that is being brought before the Supreme Court is Chatrie v. United States. Okello Chatrie was arrested for robbing the Call Federal Credit Union in Richmond, Virginia, on May 20, 2019. Surveillance footage showed the robber using a cellphone during the robbery. After exhausting other means of investigation to determine the bank robber, law enforcement obtained a geofence warrant compelling Google to provide location data for all devices within a 150-meter radius of the bank during a one-hour window around the robbery. This data ultimately identified Chatrie as a suspect.
The question before the court was whether this geofence warrant constitutes a Fourth Amendment search. The geofence process searches all the phones within that area and time and provides information to law enforcement. Private information from innocent people gets caught up in the data provided to law enforcement.
Google does not keep location data on their servers anymore. Google location data is now stored on your individual device which you can disable. This is a moot point for Google; however, law enforcement continues to use this geofence tool in the form of "tower dump" requests. The cellular operators store call logs, text logs and data session logs along with the corresponding tower sector. A tower dump of this information would be all communication logs for all phones on specific towers within a specified time period. The privacy issue is the same. If the Court strikes down the geofence warrant as unconstitutional then it is up for debate if this also applies to tower dumps.
The NPR video has a fairly non-technical overview and can be viewed here.
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