Black Box 101: Understanding Event Data Recorders (EDR)

Gathering evidence immediately after a car crash is often crucial to the success of your personal injury claim.

One increasingly important piece of evidence is a car’s event data recorder (EDR) or “black box”.

This device comes standard on most passenger vehicles manufactured in the past decade.

It records and stores information about airbag deployment, speed, brakes and even seatbelt use in the moments directly preceding a crash.

This information can help prove fault in car accident cases, ensuring you get the compensation you deserve.

This information is particularly useful in the moments leading up to the collision, as very often there is no physical evidence that can be used to establish what the driver was doing.

For example, a detailed accident reconstruction by an accident reconstruction engineer can often determine the speed of the vehicle with good precision at impact, however it is often not known whether that vehicle was accelerating, coasting, or braking in the seconds leading up to the crash.

With “black box” data, a history of up to twenty-five seconds can establish these parameters.


A car’s black box does not record information about your driving habits, identity or location. Instead, it stores data about the vehicle’s function in the seconds before and during a crash.

EDRs may differ depending on the make and model of your car, since there currently is no industry standards and regulations.

However, most record data on a continuous loop, rewriting approximately 5 to 10 seconds of information until a crash. Then, the data leading up to that collision is stored for a certain period of time.

An EDR can record data such as:

  • The forward and lateral crash force.
  • The crash event duration.
  • vehicle speed for many seconds prior to impact
  • Accelerator position.
  • Engine rpm.
  • Brake application and antilock brake activation.
  • Steering wheel angle.
  • Stability control engagement.
  • Vehicle roll angle, in case of a rollover.
  • Number of times the vehicle has been started.
  • Driver and front-passenger safety belt engagement, and pretensioner or force limiter engagement.
  • Air bag deployment, speed, and faults for all air bags.
  • Front seat positions.
  • Occupant size.
  • Number of crashes (one or more impacts during the final crash event).

Usually the download of the CDR data is relatively straight forward, however there are some circumstances where evidence spoliation can occur if the “black box” is improperly accessed.


Where fault of an accident is in issue, it is important you retain a lawyer who has experience obtaining the black box data AS SOON AS POSSIBLE.

One of the biggest challenges of any car accident claim is proving what actually happened. Most often, the at-fault driver’s insurance company will question your version of events and will usually try to blame you instead.

Black box data can help prove what circumstances led to the car crash. This information helps eliminate guesswork, and is a powerful tool to help refute false claims by the at-fault driver or their insurance company, and help prove your case.

However black box information must be retrieved quickly after a crash.

It is crucially important to get access to the black box before the car is salvaged or destroyed, or the data is written over.

Most EDRs store crash data for 200 ignition cycles, which typically means only six to eight weeks after an accident.

If a vehicle is repaired after a crash, the EDR may be replaced or lost.

Therefore, the sooner you contact an accident lawyer, the better the chances that EDR information can help your claim.

The lawyer will immediately retain an engineer to properly download and analyze the data.

Usually the black box from the other vehicle is also required. The lawyer will have to obtain access to the other vehicle as soon as possible. This will require either an agreement from the other drivers insurance company, or a court order.

We consider the crash data a “supplement” to a proper accident reconstruction. Typically, the downloaded information corroborates previous findings with respect to impact speed, Delta-V/Severity, seatbelt use and pre-crash behavior, but in many cases it is conclusive and makes your case.


I have had to extract black box evidence in over 30 cases.

In many cases the evidence was crucial in proving our case against the other driver.

Here are two examples where we would have not been successful without the black box evidence.

Case 1

In this case, our client was a passenger in a vehicle that lost control and slid into the oncoming lane.

The oncoming car collided with the vehicle and our client sustained serious injuries, including a very severe brain injury.

The insurance limits in the vehicle he was a passenger in was insufficient to cover his substantial claim for income loss and care costs.

We had a good case against the driver of the vehicle he was a passenger in, but to get full compensation for his severe injuries we had to somehow prove the oncoming driver was also partially at fault.

The driver in the oncoming car said she was driving the speed limit, and her insurer denied any fault entirely.

We immediately retained an engineer to do an accident reconstruction, including retaining the black box in her vehicle to determine her actual speed.

The black box showed conclusively she was in fact speeding about 15 k over the speed limit.

Our engineer was able to show that had she been travelling the speed limit when the car our client was a passenger in came into her lane, she could have avoided the collision completely by braking in time, and our client would not have received any injures whatsoever.

At mediation her insurer agreed to pay a significant portion of our clients damage claim.

Case 2

Our young preteen client was riding a bicycle and swerved into traffic.

The car that was coming up behind her struck her and she sustained a serious brain injury.

There were no independent witnesses.

The driver of the car insisted he was going the  speed limit, and could not avoid colliding with our client on her bike.

His insurer denied he was at all at fault accordingly.

We immediately retained an accident reconstruction engineer who has extensive experience with black boxes, and had the black box data examined.

It showed conclusively that the driver was speeding 20 k over the speed limit.

Our engineer convincingly proved that the driver could have avoided the collision completely had he been going the  speed limit.

The case was settled at mediation, with the drivers insurer agreeing he was at fault for a significant portion of our clients claim, sharing responsibility for the accident with our client.

In summary, if you are in an accident where fault is disputed, make sure you immediately consult a lawyer familiar with EDR’s to determine if an examination of the black box data may assist your case, and obtain the EDR data before it is destroyed.

Sometimes it is the only tool to prove the other driver was at fault.

Paul’s practice is limited to serious personal injury claims.

In his personal injury practice, he acts only on behalf of the injured, with an emphasis on brain injury claims, spinal injuries, death claims, and medical malpractice claims.

He has considerable experience in obtaining and using black box and EDR information to prove fault in car crash claims .

Paul may be reached at [email protected], or his direct line at 250-869-1115

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