What Cell-Site Data Really Shows
Cell-site location information shows which tower and which sector a phone used for a call or a data session. It does not pinpoint a person. A single tower can cover a wide area, neighboring sectors overlap, and a phone does not always connect to the nearest tower because of network load, terrain, and weather.
I began my career as an Assistant Public Defender in Florida’s Thirteenth Judicial Circuit, and I am one of only six attorneys in Florida, and just over a hundred in the country, recognized as a Forensic Lawyer-Scientist by the American Chemical Society. On the breath and blood chemistry I am trained in, I read the raw data myself. On DNA, fingerprints, cell-site, digital, and medical evidence, I bring in the right expert and cross-examine the State’s analyst on method, on chain of custody, and on the assumptions hiding inside the conclusion. Learn more about my background.
The Precision the State Glosses Over
Prosecutors like to show the jury a clean map with a dot on it. The honest picture is a broad, overlapping coverage area, and treating that area as a pinpoint is where the State’s story quietly overstates what the records can prove.
The Warrant Behind the Records
Under Carpenter v. United States, 585 U.S. 296 (2018), the government generally needs a warrant to obtain historical cell-site location records. Part of the defense is testing how the records were gathered, because evidence obtained without the proper process can be challenged.
Towers, Sectors, and Why Distance Is Not Location
A cell tower is usually divided into sectors, each covering a slice of the area around it, and a phone is recorded as using one sector for a given call. In a city, towers sit close together and their coverage overlaps heavily, so the area a single sector represents can be large and shared with other towers. Treating that broad, overlapping zone as a precise location is the central flaw in many State presentations.
Coverage also shifts with conditions. Network load, terrain, buildings, and weather all change which tower a phone reaches, and during a busy period a call can be handed to a tower that is not the nearest one at all. The record shows the tower the phone used, not the spot where the person was standing.
Call Records, Junk Mapping, and Overstated Testimony
Ordinary call detail records were created for billing, not for pinpoint location, and reading them as a precise track of movement asks them to do something they were never built to do. Some witnesses go further and offer so-called granulization theory, drawing tidy coverage wedges on a map as if they were measured. Courts have grown skeptical of that kind of testimony, and even the FBI’s own cell-analysis specialists caution against overstating what the data shows.
A qualified defense mapping and radio-frequency expert can put the real coverage picture in front of the jury and hold the State’s analysis to the reliability the Daubert standard requires, rather than letting a confident map stand in for proof.
How I Challenge Cell-Site Evidence
I bring in a qualified mapping and radio-frequency expert, hold the analysis to the Daubert standard in section 90.702, and show the jury the gap between what the data can support and the certainty the State claims.
The Records We Ask For, and the Warrant We Test
Carriers keep more than the basic call records the State usually relies on, including per-call measurement and signal data that can be far more telling about coverage than a simple tower list. We move quickly to preserve and obtain that material before it is purged, because it can either confirm or dismantle the State’s map. At the same time, we examine how the location records were obtained in the first place. If the government reached for historical location data without the warrant that Carpenter requires, that is a separate and powerful line of attack, on top of the science.
The bottom line is simple. Cell-site evidence can place a phone within a general area, which is sometimes useful to the State, but it is not the precise tracker a courtroom map suggests, and it never identifies who was holding the phone. Held to what the science can support, and not one step further, this evidence often shrinks from the centerpiece of a case to a detail that proves very little. My job is to make sure the jury sees the difference between a tower connection and a person standing in a particular place at a particular time.
Common Questions
Does cell-site data prove where I was?
No. It shows which tower a phone used, not where the person was standing. Coverage areas are wide and overlapping, so the data is approximate at best.
Can my phone connect to a tower that is not the closest one?
Yes. Phones connect based on signal strength, network load, and other conditions, not simply distance, so the nearest-tower assumption is often wrong.
Do police need a warrant for my location data?
For historical cell-site location records, generally yes, under the Supreme Court’s decision in Carpenter v. United States. How the records were obtained is worth examining in every case.
Can a cell-site expert really help my case?
Often, yes. A defense expert can expose how imprecise the State’s map is and how much it overstates, which can turn a centerpiece of the case into a weakness.
This page is general information about Florida law, not legal advice, and it does not create an attorney-client relationship. Florida applies the Daubert standard for expert testimony under section 90.702, Florida Statutes. The reliability of forensic evidence depends on the methods, the analysts, and the facts of each case, and the science and the law can change, so confirm anything here with counsel about your own situation. Every case is different, and past results do not guarantee a similar outcome.
