Call Detail Records (CDRs) can make or break a case. They provide time-stamped, carrier-generated logs of calls, texts, and data sessions that can confirm or refute key claims about location, timing, and phone usage. In commercial vehicle crash litigation, CDRs often sit at the center of disputes over distraction, duty hours, and credibility.
But CDRs are only useful if you can get them admitted. Authentication is the bridge between discovery and admissibility, and courts expect a defensible, well-documented foundation. The good news: with the right process, authenticating CDRs is straightforward and repeatable.
Last week we ran a poll on LinkedIn: How can attorneys authenticate CDRs for admissibility in court? The four options were:
- Carrier custodian affidavit
- Business records exception
- Expert testimony (CDR)
- Hashing + chain custody
Each is correct under the right circumstances, and together they form a robust authentication playbook. Below, we break down how to use each approach, how to combine them, and practical tips to avoid common pitfalls
1) Carrier Custodian Affidavit
The most direct path to authenticating CDRs is through a sworn statement from the carrier’s records custodian (or other qualified person) that the records are what they purport to be and were maintained in the ordinary course of business.
What to request:
- A carrier-produced CDR set in native or certified format (PDF with certification, or CSV/XML with certification).
- A custodian of records affidavit attesting:
- The records are kept in the regular course of the carrier’s business.
- Making the records is a regular practice.
- The records were made at or near the time of the events by someone with knowledge.
- The attached records are true and complete copies.
Why it works:
Courts are comfortable with business record custodial certifications. When properly drafted, these certifications satisfy the evidentiary requirements for authentication and support the business records exception to hearsay. Many carriers provide standardized certifications for litigation.
Practice pointers:
- Draft a subpoena that specifically asks for certified records with a custodian affidavit.
- Identify the relevant time window precisely (e.g., one hour pre- and post-incident).
If you need tower/sector data, specify it explicitly; generic “CDRs” requests often exclude detailed cell-site info unless asked for.
2) Business Records Exception
Authentication and hearsay are distinct issues, but they often travel together with CDRs. The business records exception to hearsay generally allows admission of records created and maintained in the regular course of a business activity.
How it supports authentication:
- The same facts that establish hearsay admissibility (regular practice, contemporaneous creation, kept in the ordinary course) help authenticate the records.
- Courts routinely accept properly certified carrier records without a live custodian when the jurisdiction allows admission by certification.
Best practices:
- Tie your offering to the relevant evidentiary rule in your jurisdiction that permits admission by certification (e.g., rules paralleling FRE 803(6), 902(11), or their state analogs).
- Keep your motion and supporting declaration clean and focused: identify the phone number(s), account holder(s), carrier, coverage dates, and exactly which exhibits correspond to which certified datasets.
When to consider a live custodian:
- If the opposing party raises a genuine challenge to the accuracy or completeness of the records.
If there are anomalies (e.g., apparent gaps, formatting issues, or unfamiliar carrier codes) that would benefit from in-court explanation.
3) Expert Testimony (CDR)
A qualified telecommunications or digital forensics expert can authenticate the technical aspects of CDRs and explain how to interpret them. This is especially helpful when you need to bridge the gap between raw data and meaning: timestamps, call setup codes, cell tower/sector mapping, and how these correlate with timelines.
What your expert can cover:
- Chain of custody for the data once received from the carrier.
- Verification that record formats and metadata are consistent with carrier standards.
- Interpretation of cell-site and sector data, including general location inferences and limitations (e.g., not GPS precise).
- Cross-referencing CDRs with other evidence (ELD data, telematics, dash cam timestamps) to validate internal consistency.
Why it matters:
Even if a certification is sufficient for admission, expert testimony enhances the persuasive value and helps the court (and jury) understand how the records tie to material facts like distraction or location. It also inoculates against common misinterpretations by opposing counsel.
Expert selection tips:
- Choose someone with carrier/CDR-specific expertise and courtroom experience.
- Ensure the expert can explain limits candidly: cell-site data gives approximate location, not pinpoint GPS.
4) Hashing + Chain of Custody
While hashing is more commonly discussed with device images or exported datasets, it also adds value when handling CDR files received in electronic form (e.g., CSV, XML, native exports). Maintaining an unbroken chain of custody and verifying file integrity with hash values makes your authentication airtight.
How to implement:
- On receipt of electronic CDRs, compute cryptographic hashes (e.g., SHA-256) and record them in your evidence log.
- Store an original, read-only copy and work from a forensically preserved duplicate.
- Document every handoff and analysis step—who accessed the files, when, and for what purpose.
Why it helps:
If the opposing party alleges tampering, you can prove that the files you analyzed match the carrier-delivered originals exactly. Hashing plus detailed chain of custody strengthens authenticity and reliability, particularly when the CDRs are central to disputed facts.
Tips for Attorneys: Make CDRs Court-Ready
- Serve preservation notices early
- Carriers’ retention periods vary. Preserve and request CDRs before they roll off retention windows.
- Ask for data dictionaries
- Carrier field codes can be opaque. Request the carrier’s field descriptions and code tables to reduce ambiguity.
- Tie records to your theory
- Build a clean timeline that places CDR events alongside crash time, ELD entries, telematics, and witness statements. Clarity persuades.
- Use visual demonstratives
- Jurors absorb timelines and simple maps better than spreadsheets. Have your expert create admissible visuals based on the authenticated data.
- Protect privacy and proportionality
Tailor requests narrowly to incident-relevant windows. Courts appreciate proportional discovery focused on real issues.
Conclusion
Authenticating CDRs is not an evidentiary obstacle course. With a carrier custodian affidavit, reliance on the business records exception, a qualified expert to translate and contextualize the technical data, and rigorous hashing plus chain of custody, you can create a rock-solid foundation for admissibility.
For civil litigators—especially in commercial vehicle crash cases—the formula is clear:
- Get certified records from the carrier.
- Document integrity and custody from day one.
- Use expert testimony to explain and connect the dots.
- Present the evidence with clarity, candor about limitations, and relevance to your theory.
Do this consistently, and your CDRs won’t just be admissible—they’ll be persuasive.
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If you have any questions please contact me at ben@braveinvestigations.com