Every commercial truck carries an Electronic Logging Device that records speed, braking, and hours driven. This data is critical evidence in crash cases — but trucking companies can legally destroy it after 6 months. Here's how to preserve it before it's gone.
When a semi truck crashes, the most powerful evidence of what happened is often sitting inside the truck itself — in a small device called the Electronic Logging Device, or ELD. Understanding what this data contains, how long it's retained, and how to preserve it can be the difference between winning and losing a truck accident case.
What Data the Black Box Records
Modern commercial trucks carry two primary data recording systems:
Electronic Logging Device (ELD):
Event Data Recorder (EDR) / Engine Control Module (ECM):
Together, these systems can reconstruct exactly what the driver was doing in the minutes and seconds before a crash — and whether they were operating legally.
The 6-Month Destruction Window
Here is the critical fact that every truck accident victim needs to know: federal regulations only require carriers to retain ELD data for 6 months. After that, the data can be legally deleted.
Trucking companies and their insurers know this. In cases where the data shows driver negligence, carriers have been known to allow the retention period to expire before producing records in litigation.
How to Preserve the Data: Send a Spoliation Letter
The moment you retain an attorney, they should send a spoliation letter — a formal legal notice demanding that the carrier preserve all data related to the crash. Once a carrier receives this letter, destroying the data constitutes spoliation of evidence, which courts can penalize severely, including by instructing the jury to assume the destroyed evidence was unfavorable to the carrier.
A spoliation letter should demand preservation of:
Real Cases Won With Black Box Data
In a 2024 case in Harris County, Texas, black box data showed a driver was traveling 74 mph in a 55 mph zone and had been on duty for 16 consecutive hours at the time of a crash that killed two people. The carrier settled for $4.2 million before trial.
In a 2025 Florida case, ECM data proved the driver never applied the brakes before a rear-end collision that left a passenger permanently paralyzed. The jury awarded $7.8 million.
Were you or a loved one injured in a truck accident?
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