Dedicated to the pursuit of justice

What Is the Semi Truck’s Black Box and How Can It Be Used as Evidence?

June 28, 2021 Trucking Accident

An in-depth investigation into a truck accident is paramount in building a solid case, including retrieving data from the truck’s black box. A black box’s job is to store data related to the truck driver’s performance, which can ultimately help prove that a trucking company or their driver was negligent. 

What Is a Black Box?

Officially called an event data recorder (EDR), but more commonly referred to as a black box, is a small device that records data on a truck or tractor-trailer’s physical details and how it is traveling. There are different types of black boxes, but generally, the recorded data from a commercial truck is transmitted to a trucking company or third-party company when the vehicle is involved in an accident. 

Information Stored on a Black Box

Black boxes contain a wide variety of vehicle data and typically record 30-day periods before writing over the data. Some of the most common information found that can be used as evidence in a truck accident case includes: 

  • The truck’s speed just before the collision;
  • Engagement of the clutch;
  • Sudden deceleration;
  • If and when the truck driver applied any brakes;
  • Steering angles;
  • Throttle position;
  • Tilt of the vehicle;
  • Following distance;
  • Force of impact;
  • Airbag deployment times;
  • If a seatbelt was engaged;
  • How frequently the truck is driven above a speed limit that is predetermined on the vehicle;
  • Daily or monthly engine activity that shows if the hours traveled exceed regulations;
  • Maintenance issues;
  • Tire pressure, and more. 


This data can be crucial evidence of fault. For example, if the truck driver was speeding and didn’t apply the brakes—which can indicate distracted driving, or if required rest breaks were not taken—that could indicate driver fatigue. Any of these violations could prove the driver or the trucking company’s liability and support your claim for compensation.

How to Secure Black Box Data

A trucking company and its insurance company are not going to hand over this evidence easily. They will likely need to be compelled by the court to do so. The first step in securing black box data is hiring a truck accident lawyer to send a spoliation letter. This letter requests a trucking company and its insurer to preserve all evidence related to the accident and warns against destroying or tampering with it. If the trucking company still refuses to hand over some or all of the data, your attorney can petition the court for a temporary injunction to prevent the company from destroying the evidence until there is a court hearing. 

It is critical to ensure that black box information is not lost or destroyed in the immediate aftermath of the accident. Evidence at the scene can quickly disappear, or a trucking company may instruct or allow employees to take steps that destroy proof of liability. A black box will be vital in validating the cause of your injuries. 

Have You Been Injured in a Truck Accident, Speak With A Truck Accident Lawyer Today? 

If you or someone you love has recently been involved in a serious truck accident, contact CaseyGerry. Our truck accident lawyers in San Diego, have extensive experience obtaining and interpreting black box data. With our help, you may be able to recover significant compensation. Call (619) 238-1811 for your free consultation today.