CDR Mapping: 7 Questions Every Attorney Should Ask the Expert
CDR mapping can win or lose a case. The methodology is unforgiving, the data is short lived, and the difference between a defensible exhibit and a Daubert problem often comes down to seven specific questions. Ask them before you retain the expert, not on the witness stand.
1. Did you confirm the carrier production is complete?
Carrier productions are often partial. A defensible analyst reconciles record counts against the request, flags gaps, and asks for missing items before mapping anything. If the expert mapped the file as delivered without auditing it, that is a problem.
2. What tower data did you use, and when was it updated?
Sector azimuths, beamwidths, and tower lat/long change. Using stale data shifts the apparent coverage area, sometimes by miles. Ask whether the analyst used the carrier’s contemporaneous tower list or a current public dataset, and confirm the dates align with the records.
3. How are you handling timezones?
Carrier records are commonly produced in UTC or in a regional timezone. A small timezone error can move every connection in the timeline. The report should state the source timezone, the conversion applied, and the timezone shown in every exhibit.
4. Can you distinguish coverage area from a GPS point?
A defensible report describes coverage as a sector wedge with realistic limits, not as a pin on a roof. If the expert is drawing GPS style markers, ask them to articulate the precision they are claiming and the basis for it. Under Carpenter v. United States, the limits of CSLI are not academic.
5. What can the data not tell us?
An honest expert volunteers limitations: the device, not the user; the sector, not the building; the metadata, not the content. If your expert has no limitations slide, your opposition will provide one for them.
6. Did you preserve the data, and when?
Carrier retention is short. Per call measurement data, NELOS, and text content can disappear in days. A 2703(f) preservation letter at the start of the matter is the difference between a complete record and an incomplete one. Ask when preservation was sent and to whom.
7. Are you prepared to defend the methodology at deposition?
The strongest CDR experts welcome the methodology section of cross examination. They can walk through the source data, the parsing logic, the tower geometry, the timezone handling, and the final exhibits without retreating. If the expert is uncomfortable with method questions, the report will be uncomfortable in court.
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