Cell site location analyst
Expert class library · Forensic science · Either side
A law enforcement or defense analyst who uses a phone carrier's call detail records and the locations of cell towers to estimate where a phone was at the time of a crime. Courts widely accept historical cell site analysis for placing a phone in a general area, often without a reliability hearing, but they police overstatement: the method shows which tower and sector a phone used, not a precise location, and courts have required analysts to explain those limits or cautioned that evidence overpromising on precision may be an abuse of discretion.
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What this expert is retained to answer
- What does the analysis actually show: the tower and sector a phone used, or a precise location?
- How large is the coverage area of the relevant sectors, and does it include other places the phone could have been, such as the defendant's home?
- Did the analyst conduct a drive test, and how close in time was it to the events?
- Do the maps and charts suggest more precision than the data supports?
- Is the analyst relying on granulization or other contested techniques for narrowing location?
Methods
- Analysis of carrier call detail records and cell site lists
- Mapping of tower locations, sectors and azimuths
- Coverage estimation and drive testing
- Timing advance and network-based location data where available
- Comparison of the phone's activity with crime scene locations and times
How the testimony is attacked
- Overstated precision. Maps that draw a phone into a small wedge can mislead. In United States v. Medley the court admitted an FBI analyst's testimony but required him to explain the limits of his method's ability to place the defendant's phone at the carjacking scene.
- Juror overestimation. Appellate courts warn that jurors may overvalue the evidence. In United States v. Hill the Seventh Circuit affirmed admission but cautioned that historical cell site evidence overpromising on precision may be an abuse of discretion.
- Need for a reliability hearing. Defendants seek hearings on the method. In People v. Shanks the Colorado Court of Appeals held general historical cell site analysis is widely accepted and needs no hearing, while distinguishing the more controversial granulization theory.
- Network factors ignored. Phones do not always connect to the nearest tower; load, terrain, antenna height and handoffs all affect which site serves a call.
- Lay opinion in disguise. Courts disagree about when an officer reading call records and mapping towers must be qualified as an expert.
What the public record shows
Courts have filed at least 170 opinions since 2015 that address this class of testimony under Daubert or Rule 702, as of October 4, 2026. Three that show how courts handle this class of testimony:
| Outcome | Case | Court | Year | Why |
|---|---|---|---|---|
| Limited | United States v. Medley312 F. Supp. 3d 493 | D. Md. | 2018 | In a carjacking case where the masked assailant could not be identified, the court granted in part a motion to limit an FBI cellular analyst's testimony, admitting his historical cell site analysis but requiring him to explain the limitations of his method's ability to locate the defendant's phone relative to the crime scene. |
| Admitted | United States v. Hill818 F.3d 289 | 7th Cir. | 2016 | The Seventh Circuit affirmed admitting an FBI agent's historical cell site analysis in a bank robbery case because the jury heard its pitfalls and imprecision, while cautioning the government that evidence overpromising on the technique's precision may be an abuse of discretion. |
| Admitted | People v. Shanks2019 COA 160 | Colo. App. | 2019 | As a matter of first impression, the Colorado Court of Appeals held that using historical cell site data to determine a phone's general geographic location is widely accepted as reliable and does not require a reliability hearing, distinguishing the controversial theory of granulization, and affirmed the conviction. |
Each case links to the free opinion text on CourtListener.
Under amended Rule 702
Since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
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Last reviewed October 4, 2026. How this page is built: rulings are found by searching court opinions on CourtListener, and each one is read in the opinion before it is summarised here; outcomes are labelled by what the court did with the expert's testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling.