Truck Wreck Evidence
What a truck's black box and ELD record, how long carriers must keep logs under FMCSA rules, and why a fast spoliation letter matters in Kentucky.
Reviewed by Larry Forman, Attorney
After a crash with a semi-truck, the most important evidence often isn’t at the scene. It’s stored inside the truck’s computers, the carrier’s logging system and the company’s files.
That evidence can show how fast the truck was going, whether the driver braked, how long the driver had been on duty, and whether the truck was properly maintained. It can also disappear. Federal rules only require carriers to keep many records for months, not years. Some electronic data can be lost much sooner.
This guide explains what a truck’s “black box” and electronic logging device (ELD) record, how long federal rules require trucking companies to keep key records, and how a preservation (spoliation) letter protects the evidence in a Kentucky truck case.
“Black box” usually refers to a truck’s engine control module (ECM) or a related event data recorder (EDR). These are electronic units that manage the engine and can store data about how the truck was being driven.
Depending on the engine and its settings, a heavy truck’s ECM may store information such as:
There’s no single federal rule that tells heavy-truck makers what the black box must record. The federal EDR standard in 49 CFR Part 563 applies to passenger cars, SUVs, light trucks and buses with a gross vehicle weight rating of 8,500 pounds or less (49 CFR 563.3). A loaded tractor-trailer is far heavier than that. So what’s available depends on the specific truck, and getting it usually takes trained technicians with the right equipment.
Many trucks also carry forward-facing or driver-facing cameras and telematics systems that track location, speed and hard-braking. Federal rules don’t require these, but many carriers use them, and their data can be just as important as the ECM.
Most interstate truck drivers have to log their hours with an electronic logging device (ELD). Federal rules required motor carriers to install ELDs and require drivers to use them no later than December 18, 2017 (49 CFR 395.8(a)(1)(i)). There are limited exceptions, including some short-haul drivers, drivers who keep paper logs no more than 8 days in any 30-day period, certain driveaway-towaway operations, and trucks with engines older than model year 2000 (49 CFR 395.8(a)(1)(ii); 49 CFR 395.1(e)).
Under 49 CFR 395.26(b), an ELD automatically records:
The ELD records these items whenever the driver changes duty status, and automatically at least once an hour while the truck is moving if nothing else has been recorded (49 CFR 395.26(d)). It also records engine power-up and shut-down, logins and logouts, and malfunctions.
Federal rules also make it illegal for a driver or carrier to disable, jam or tamper with an ELD so that it doesn’t accurately record and retain data (49 CFR 395.8(e)).
ELD data matters most when it’s compared to the federal hours-of-service rules. For property-carrying trucks, 49 CFR 395.3 says a driver:
When the ELD, fuel receipts, GPS data and delivery records don’t line up, that gap can show a tired driver or a schedule that pushed the driver past the limits.
Federal Motor Carrier Safety Regulations (FMCSRs) require trucking companies to keep many records. Kentucky has adopted these federal safety rules for both interstate and intrastate carriers, with some state variations (601 KAR 1:005). Key records include:
Beyond what the regulations require, a case may also turn on:
This is where timing becomes critical. Here are the minimum retention periods in the federal rules:
| Record | Minimum federal retention | Regulation |
|---|---|---|
| Driver’s records of duty status (logs) and supporting documents | 6 months from receipt | 49 CFR 395.8(k)(1) |
| Back-up copy of ELD records (on a separate device) | 6 months | 49 CFR 395.22(i) |
| Driver vehicle inspection reports and repair certifications | 3 months | 49 CFR 396.11 |
| Vehicle inspection, repair and maintenance records | 1 year, and 6 months after the vehicle leaves the carrier’s control | 49 CFR 396.3(c) |
| Driver qualification file | Length of employment plus 3 years (some items can be removed after 3 years) | 49 CFR 391.51(c)–(d) |
| Accident register | 3 years after each accident | 49 CFR 390.15(b) |
| Alcohol results of 0.02 or higher, verified positive drug results, test refusals | 5 years | 49 CFR 382.401 |
| Negative and canceled drug test results; alcohol results below 0.02 | 1 year | 49 CFR 382.401 |
Regulations as published in the eCFR, current through October 2026.
Two things stand out. First, the logs and inspection reports that best show what happened in the days before a crash can be discarded in as little as 3 to 6 months. Second, black box data and camera footage don’t have federal retention periods at all. Some systems record over older data automatically, and an ECM’s stored events can be lost if the truck goes back into service or is repaired.
The Kentucky statute of limitations for a truck crash injury lawsuit is generally two years (KRS 304.39-230(6)). The evidence can be gone long before that. (See our Kentucky statute of limitations guide.)
A spoliation letter, also called a preservation letter or litigation hold letter, is a formal written demand that the trucking company and others keep all evidence related to the crash. “Spoliation” means destroying or failing to preserve evidence.
A strong letter is specific. It usually:
When a carrier refuses to cooperate, lawyers can ask a court for orders to protect evidence and allow an inspection. Downloads are often done under a joint protocol, where qualified technicians for both sides are present so no one can later question how the data was handled.
Kentucky doesn’t allow a separate lawsuit just for destroying evidence. The Kentucky Supreme Court declined to create that claim in Monsanto Co. v. Reed, 950 S.W.2d 811 (Ky. 1997). Instead, Kentucky courts handle missing evidence through evidence rules and jury instructions.
In University Medical Center, Inc. v. Beglin, 375 S.W.3d 783 (Ky. 2011), the Court explained that when material evidence in a party’s exclusive control is lost without explanation, the jury can be instructed that it may infer the evidence was intentionally destroyed and would have been unfavorable to that party.
That instruction can be powerful. But it’s no substitute for having the actual data. Getting the letter out quickly is far better than arguing about missing evidence later.
Some information about a motor carrier is public. The Federal Motor Carrier Safety Administration (FMCSA) publishes carrier registration and safety information, searchable by USDOT number, through its SAFER system. Inspection and violation history can point to patterns, like repeated brake or hours-of-service problems, that are worth investigating.
Federal rules also set minimum insurance levels for many interstate trucking companies. For a for-hire carrier hauling non-hazardous property in a vehicle with a gross vehicle weight rating of 10,001 pounds or more, the minimum is $750,000. It’s higher for certain hazardous materials: $1,000,000 or $5,000,000 depending on the cargo (49 CFR 387.9).
Large trucks are a regular part of Louisville traffic, with I-64, I-65 and I-71 all meeting downtown. Statewide, the Kentucky State Police’s 2024 Kentucky Traffic Collision Facts report counted 9,736 collisions involving trucks (vehicles registered at 10,000 pounds or more) in 2024. 99 of them were fatal and 1,367 involved injuries. Among truck drivers in those collisions whose residence was known, 41% lived outside Kentucky, which can affect where witnesses and records are located.
See more on our Kentucky car crash statistics page.
If you or a family member was hurt in a truck crash:
When we take a truck case, we:
Learn more on our truck wreck lawyer page, or read why commercial truck wrecks are different from car crashes. If the crash involved a delivery van, bus or other work vehicle, see our commercial vehicle crash page.
Most modern heavy trucks have an engine control module that can store driving data, but what it records depends on the engine and its settings. Federal EDR rules (49 CFR Part 563) apply only to vehicles of 8,500 pounds GVWR or less, so there’s no single standard for heavy trucks.
Federal rules require carriers to keep drivers’ records of duty status and supporting documents for at least 6 months (49 CFR 395.8(k)), and a back-up copy of ELD records for 6 months (49 CFR 395.22(i)).
Usually not. The truck and its data are controlled by the carrier or owner. Getting the data typically requires a preservation demand, cooperation or a court order, and technicians with specialized equipment.
It’s a written demand that the trucking company and others keep all evidence related to the crash, including electronic data, logs, maintenance records and the truck itself.
Kentucky doesn’t recognize a separate lawsuit for destroying evidence, but a court can instruct the jury that it may infer lost evidence would have hurt the party that lost it (University Medical Center v. Beglin, 375 S.W.3d 783 (Ky. 2011)).
Kentucky has adopted the federal motor carrier safety regulations for both interstate and intrastate operations, with some state variations (601 KAR 1:005).
The sooner preservation letters go out, the more evidence survives. Talk with our team about your truck crash today. Get a free case evaluation or call 502-931-6788.
More answers: our Personal Injury FAQ and the Kentucky Injury Resource Center.
This page is general information, not legal advice. Federal and state rules change, and every case depends on its own facts.
