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Types of Cell Phone Location Data
There are several distinct types of location data that prosecutors may use, each with different levels of reliability:
Cell Site Location Information (CSLI)
Every time your phone makes or receives a call, sends a text, or uses data, it connects to a nearby cell tower. Your carrier’s records document which tower handled each connection. Prosecutors use this information to argue that you were in the general area of a particular tower at a particular time. The problem: a single cell tower can cover an area of several square miles, and the fact that your phone connected to a particular tower does not mean you were at any specific point within that coverage area. In urban areas with dense tower placement, the coverage areas are smaller but still imprecise. In rural areas, a single tower may serve a very large geographic zone.GPS Data from the Phone
Smartphones contain GPS receivers that can determine the phone’s location with much greater precision — sometimes within a few meters. This GPS data is captured by apps, by the phone’s operating system, and by services like Google Location History. When available, GPS data is more precise than cell tower data, but it is not always recorded continuously and is dependent on having GPS signals available.Call Detail Records (CDRs)
Call detail records document the cell towers used for calls and data sessions, along with timestamps, duration, and the numbers involved. Prosecutors use CDRs to construct a historical narrative of a phone’s movements.
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Why Cell Phone Location Evidence Is Less Reliable Than Prosecutors Claim
Doug’s training with Garrett Discovery has given him direct knowledge of the limitations of cell phone location evidence. Garrett Discovery’s experts have written numerous reports debunking the use of call detail records to pinpoint exact locations and Doug brings that same analytical framework to every case:- Cell towers do not pinpoint location. A phone connecting to a tower means only that the phone was within that tower’s coverage area — which can span miles. Prosecutors who claim CDR evidence “places the defendant at the scene” are overstating what the data shows.
- Coverage areas overlap. A phone may connect to one tower rather than a closer tower due to network load balancing, signal strength variations, or physical obstructions. The tower used is not necessarily the nearest tower.
- Historical CSLI is not real-time tracking. CSLI data shows which tower handled a particular event at a particular time. It does not provide continuous tracking between events. The prosecution may present a series of tower connections as a “path,” but there are gaps between data points that the prosecution fills with inference.
- A phone’s location is not a person’s location. Cell phone location data shows where the phone was, not where the person The phone could have been left somewhere, carried by someone else, or in a vehicle that the defendant was not in.
The Carpenter Decision and Warrant Requirements
In Carpenter v. United States (2018), the Supreme Court held that the government generally needs a warrant to obtain historical cell site location information from a wireless carrier. The Court recognized that long-term CSLI data reveals an intimate picture of a person’s life and movements that is protected by the Fourth Amendment. Doug evaluates every case for Carpenter compliance: Was a proper warrant obtained? Did the warrant specifically authorize the collection of location data? Was the scope of the data collected proportionate to the investigation?How Doug Challenges Location Evidence
Doug works with independent digital forensics experts to:- Map the actual coverage areas of the cell towers identified in the prosecution’s evidence to demonstrate the imprecision of CSLI data
- Analyze whether the prosecution’s cell tower evidence is consistent with the defendant’s actual location or equally consistent with other locations
- Extract and present the defendant’s own GPS data, Google Location History, and device location records to build an alibi defense
- Challenge the qualifications and methodology of the prosecution’s cell tower analyst
Case Results
Talk to a Defense Team That Understands Digital Evidence
At Deandra Grant Law, Attorney Douglas Huff is our Partner and Criminal Division Chief — a senior trial attorney who has completed advanced training in digital forensics with Garrett Discovery, one of the nation’s leading digital forensics firms. Doug doesn’t just read the prosecution’s forensic reports. He has the training to understand the tools, challenge the methods, and expose the weaknesses in digital evidence. If you are facing criminal charges involving digital evidence of any kind, contact Deandra Grant Law for a free, confidential consultation. Call (214) 225-7117 or schedule an appointment online at texasdwisite.com.Firm Accolades
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