ELD Data and the 6-Month Evidence Window: Preserving Commercial Truck Accident Evidence Before It's Gone

Commercial truck accident cases turn on evidence that disappears faster than most plaintiffs realize. The Federal Motor Carrier Safety Administration requires carriers to retain hours-of-service and electronic logging device data for as little as six months. Dashcam footage retention windows are even shorter. A vehicle stores black box and event data recorder information until its next service, when it overwrites most of that data. By the time most injured victims decide to pursue a claim, they have already lost the strongest evidence for their case.

This article walks through the FMCSA evidence retention rules, the practical timeline of evidence decay, the preservation steps that matter most in the first 60 days, and the chain-of-custody considerations that make or break commercial truck cases at trial.

The FMCSA retention framework

Federal Motor Carrier Safety Administration regulations under 49 C.F.R. Part 395 govern hours-of-service tracking and the electronic logging device mandate that took full effect in 2017. The key retention rules for litigation purposes:

ELD records (49 C.F.R. 395.22 and 395.24): Carriers must retain ELD data for six months from the date the record was created. This is the minimum. Some carriers retain longer under internal policy, but six months is the federal floor.

Hours-of-service supporting documents (49 C.F.R. 395.11): Records of duty status, including bills of lading, dispatch records, weight tickets, fuel receipts, toll records, and trip reports, must be retained for six months.

Daily driver vehicle inspection reports (49 C.F.R. 396.11): Retained for three months from the date of preparation, then can be destroyed unless preserved for an open investigation.

Post-accident drug and alcohol testing records (49 C.F.R. 382.401): Retained for five years for positive tests, one year for negative tests.

Maintenance records and repair history (49 C.F.R. 396.3): Retained for one year while the vehicle is under the motor carrier's control, six months after the vehicle leaves the carrier's control.

The six-month ELD retention window is the most consequential rule for accident litigation. After six months, the carrier may legally destroy ELD records that would otherwise establish the driver's hours, location, speed, and braking patterns at the time of the crash.

Why ELD data matters in injury cases

ELD systems on commercial vehicles capture far more than hours of service. Modern ELD platforms record:

• Driver duty status (driving, on-duty not driving, off-duty, sleeper berth) in 15-minute intervals
• Vehicle GPS location at regular intervals
• Vehicle speed and acceleration patterns
• Engine on/off events
• Hard braking events
• Lane departure warnings (on vehicles equipped with lane assist)
• Forward collision warnings

In a crash case, this data answers the question that almost always determines liability: Was the driver fatigued? Was the driver speeding or braking before impact? Was the driver showing any patterns of driver-assistance system warnings before the crash?

A driver who was 14 hours into a duty cycle when a crash occurred is a different liability profile than one who was 2 hours in. A driver with 12 hard-braking events in the preceding hour was driving differently than one with zero. The ELD data establishes these facts objectively.

The preservation timeline

Day 0 (crash): All evidence still exists.

Day 1-3: The carrier dispatches its investigators. ELD data is reviewed internally, and the carrier's defense strategy begins forming around what the data shows.

Day 14-30: The carrier completes its internal investigation. Documentation that was kept for investigation purposes may be filtered, with some items moved to long-term retention and some destroyed under routine record retention policies.

Day 30-90: Daily vehicle inspection reports start aging out (three-month retention). Dashcam footage from third-party fleet management systems may already be overwritten.

Day 90-180: ELD records are approaching the six-month destruction window. Carrier may legally destroy them on day 181.

Day 180+: Most case-relevant evidence is gone unless a litigation hold was issued.

The practical implication: from day one of the crash, the plaintiff has roughly six months to send a preservation demand before the most valuable evidence becomes legally destructible.

The preservation demand

A preservation letter sent to the carrier within the first 14 days of the crash is the single most important pre-litigation document in any commercial truck case. The letter should:

1. Identify the crash by date, time, location, and vehicle information (DOT number, truck number, license plate)
2. Demand preservation of all ELD records for the driver covering at least 30 days before the crash and 30 days after
3. Demand preservation of all hours-of-service supporting documents for the same period
4. Demand preservation of all dashcam footage from forward-facing, in-cab, and any external cameras, covering the 24 hours before and 24 hours after the crash
5. Demand preservation of vehicle maintenance records for the truck, trailer, and any equipment involved
6. Demand preservation of driver qualification file documents, including medical certifications, training records, and any prior accident or violation records
7. Notify the carrier of potential litigation and request that all routine destruction policies be suspended pending resolution

The letter should be sent via certified mail with return receipt and via email to the carrier's safety director and general counsel. If the carrier has insurance, the letter should also go to the insurance carrier's claims department.

After the preservation letter, defense counsel cannot credibly claim routine destruction was inadvertent if evidence later disappears. Spoliation sanctions become available.

Chain of custody for ELD data

Once preserved, ELD data must be obtained in a forensically sound manner. Three considerations:

Native format. Request the data in the ELD provider's native format (typically a proprietary file format that includes metadata, timestamps, and audit trails). Do not accept summary reports or screen captures. Native files are required to rebut authenticity challenges at trial.

Custodian declaration. Request a custodian declaration from the carrier identifying when the data was retrieved, who retrieved it, and the chain of custody since retrieval. This becomes the authentication foundation at trial.

Independent expert analysis. Engage an ELD or commercial vehicle data expert to review the native data. The expert can identify patterns, anomalies, and contradictions that a non-specialist would miss.

The driver qualification file

In addition to ELD data, the driver qualification file under 49 C.F.R. 391.51 contains evidence that often decides cases:

• Driver's commercial license history
• DOT medical certifications
• Pre-employment drug and alcohol test results
• Road test results
• Driver training records
• Previous accident history
• Previous violation history
• Annual review of driving records

The driver qualification file is required to be retained throughout the driver's employment plus three years after termination. This is a longer retention window than ELD data, but the file is often the first thing carriers review for liability exposure and the first thing defense counsel produces strategically (or refuses to produce).

A preservation demand should include the driver qualification file along with the ELD and supporting documents.

Common defense tactics around ELD evidence

Defense counsel has predictable responses to ELD preservation demands:

1. Slow-roll production. Defense will produce ELD data only after multiple discovery motions, often months into litigation. The strategy: by the time the plaintiff's expert reviews the data, the carrier has had time to develop counter-narrative based on it.

2. Selective production. Defense will produce ELD data for the immediate timeframe (the day of the crash) while resisting production of the 30-day window before and after. Pattern evidence (recurring fatigue, recurring hard braking) requires the longer window.

3. Native format resistance. Defense will produce PDF summaries or printouts rather than native data files. The native files are required for forensic analysis but harder to manipulate or contextualize for the jury without expert testimony.

4. Privacy and trade secret objections. Defense will assert privacy concerns for the driver and trade secret concerns for the ELD provider's proprietary format. These are usually overcome with a protective order but the friction is real.

5. Authenticity challenges at trial. Even after production, defense will challenge the authenticity of the ELD records on the theory that the carrier's electronic systems are unreliable. This is why custodian declarations and chain of custody documentation matter.

Practical advice for practitioners

For attorneys handling commercial truck crash intake:

1. Send the preservation letter on day one or day two. Do not wait for full client engagement, full investigation, or full damages assessment. The letter goes out before any of that.
2. Identify the right recipient. The carrier's safety director, the carrier's general counsel if available, and the carrier's insurance company. Multiple recipients prevent the "the letter went to someone else" defense.
3. Engage the ELD expert early. Most experts can review native data in 30 to 60 days. Engagement on day 30 means an expert report by day 90, which means depositions of the driver and safety personnel can be informed by the data analysis.
4. Treat day 180 as the litigation-must-be-filed deadline. If the case is not in litigation by six months from the crash, ELD evidence is at risk of legal destruction.

For attorneys representing carriers:

1. Issue an internal litigation hold immediately. Even if no preservation letter has arrived, the obligation to preserve attaches when litigation is reasonably foreseeable. A serious injury crash usually triggers this.
2. Document the hold. Internal documentation of when the hold was issued, what was preserved, and who received the notice becomes the spoliation defense if records later go missing.
3. Produce in native format when ordered. Resisting native format production usually loses on motion and damages credibility with the court.

The commercial truck case is won or lost in the first 60 days. The evidence preservation steps are not optional.

See also: Idaho's 2-Year Statute of Limitations: What Treasure Valley Crash Victims and Their Attorneys Need to Know, Idaho Uninsured Motorist Claims | UM/UIM Coverage Guide