What is your car’s “Black Box” and how it affects personal injury law.

Black boxes are essentially computers in your car that store data prior to a crash. Black boxes are mandatory in the United States:


Although black boxes are not mandatory in Canada, they do come pre-installed on the vast majority of new vehicles. These black boxes only typically store information from the first 20 or so seconds prior to a motor vehicle accident. They store a variety of information, including:

  • vehicle speed
  • throttle position
  • airbag deployment times
  • brake pressurew
  • which seatbelts were being worn
  • engine speed
  • steering angles

During many personal injury cases liability is in dispute. People argue over a variety of factors that are crucial to a proper determination of liability. The problem with evidence from people is that it is not always accurate: memories fade, people are biased, some people lie, witnesses don’t always see the whole event, etc…

A black box, assuming it is functioning properly, will provide objective data. The black box, therefore, can provide people some protection from other parties who are willing to lie about what happened in an accident.

In a recent personal injury case I worked on, the plaintiff had been accused of speeding through an intersection after being struck by a car making a left turn. Typically in these situations there is a presumption that the car making the left turn is at fault, as cars making left turns must yield to oncoming traffic. This presumption can be overturned if the oncoming vehicle is shown to be speeding or going though a red light.

The black box data, in this case, came from the vehicle making the left turn. It showed that the defendant’s testimony did not match the facts. Her story was that she’d come through what was a clear intersection and had been struck by a speeding vehicle. The black box data, however, showed that she had, in fact, stopped at the intersection and then hammered on the accelerator in an attempt to make a left turn without properly yielding. Using the data from the black box, we were able to hire an forensic¬†engineer to support the plaintiff’s claim and successfully argue her case.

Black box