Will Jones
Event data recorders capture about five seconds. A Michigan trial lawyer explains what a car black box actually stores, what it doesn’t, and how fast the rest disappears.
The car had been taking notes.
A man was driving through an intersection on a green light, under the speed limit, when a county truck ran the red and stayed in the intersection for more than three seconds. He was paralyzed. He died about a year later.
His vehicle carried an event data recorder — the device most people call a car black box. It could have shown how fast he was going in the seconds before impact, whether he braked, where the accelerator was, and whether his seat belt was latched.
Nobody ever read it. The car was destroyed before anyone examined it.
Then the defense told a jury he had not been wearing his belt, relying on an expert who had never seen the vehicle and who had sworn in her own affidavit that no detailed review could be made from the surviving photographs.
That case is why Michigan trial lawyer Joseph Dedvukaj wrote Your Car Is a Witness, a book about vehicle data after a car accident — what modern cars record, who can obtain it, and how quickly it disappears.
What does a car black box actually record?
Less than most people assume, and under a rulebook most have never read.
Federal regulation defines an event data recorder as a device or function that records a vehicle’s dynamic time-series data just before or during a crash, intended for retrieval afterward. For covered vehicles equipped with one, the rule specifies what must be captured and in what format — historically a five-second window before the event, sampled twice per second: indicated speed, accelerator or throttle position, and whether the service brake was on or off.
Five seconds. Eleven samples per element.
The same regulation states expressly that event data do not include audio or video.
So the federal black box is a real witness with a real rulebook, and a narrow one. It is not the dash camera. It is not the navigation history. It is not the phone that was paired to the car. Those systems sit in the same vehicle, are governed by no comparable federal rule, and often hold far more.
That gap is the book’s subject. The useful question after a modern crash is not does this car have a black box. It is: what systems were in this particular vehicle, what did they actually record, what still exists, and who has it?
Can EDR data prove how fast a car was going?
Sometimes. But a recorded number is not a finding, and this is where Dedvukaj turns against the instinct his own book creates.
Electronic evidence carries an authority that human memory does not. A figure on a printout looks like fact. The book spends much of its length explaining why that confidence has to be earned.
Consider delta-V, the reported change in velocity. Under the federal specification it carries an accuracy tolerance of plus or minus ten percent. It measures how that vehicle’s velocity changed during the recorded event. It is not impact speed, not the other vehicle’s speed, and not the closing speed between them — though it gets described as all three in briefs.
Consider timing. The recorder’s time zero is not necessarily the instant the vehicles touched. Under the rule it is a system-defined reference point tied to the restraint architecture: it may be when a wake-up algorithm activates, or when a non-reversible restraint deploys. Every time in the report is measured from that defined zero, not from a later reconstruction of impact.
The rule also states that pre-crash and crash data are asynchronous, giving pre-crash samples their own tolerance. A field labeled one second before time zero may have occurred anywhere from 1.1 seconds before it to time zero itself.
Sample rate is not simultaneity. Brake “on” is not brake force. Accelerator percentage is what the driver requested, not what reached the wheels.
The book’s formulation: a number produced by a vehicle is evidence. It is not ground truth.
How long does crash data last?
This is the most practical idea in Your Car Is a Witness, and the least technical.
Retention is not one clock. Every source runs on its own, and they are not the same length.
- The vehicle runs on a disposition clock — repair, auction, scrapping, module replacement.
- A camera runs on an overwrite cycle set by its configuration.
- A phone changes every day it keeps being used.
- A telematics provider deletes on a schedule invisible from outside the company.
- A commercial carrier may owe a six-month federal retention duty for certain duty-status records while a camera file from the same trip carries no comparable obligation at all.
Then there is the clock most people do track: the deadline to file a claim, often measured in years.
Meeting that one protects nothing else. A statutory deadline and an overwrite cycle are different clocks, and neither warns you about the other.
Hence the book’s blunt advice: the time to ask what a vehicle may know is before the vehicle is gone.
What about lane keeping, adaptive cruise and self-driving features?
California is where advanced driver-assistance systems reach ordinary drivers first, on roads already carrying conventional cars, motorcycles, delivery vans, rideshare vehicles and cyclists.
ADAS raises a category of evidence question that did not exist a decade ago. Was a system engaged? What was it doing? What was the driver expected to be doing? What happened in the seconds before control changed hands?
Dedvukaj is careful about the legal answer. At the assistance levels most drivers actually encounter, responsibility never transfers to the machine. The car may help steer. The driver is still the driver. That is not a philosophical position; it is the definition of what was purchased.
What should you do after a crash?
The book opens with a page for readers who have already been in one, and its guidance is deliberately narrow.
Do not assume the police report captured or preserved the electronic evidence. Do not let a relevant vehicle be repaired, sold, auctioned or scrapped before someone has considered what it may still contain. Do not reset, wipe or trade a phone, and do not attempt a self-help extraction — well-meant handling can alter what is there or complicate a proper acquisition later.
Make a list of what might have been watching: a dash camera, the vehicle’s own recorder, a fleet or insurance telematics account, a rideshare or delivery app, a driver-assistance system, somebody else’s phone. Each is a separate source, often held by a separate company, on a separate clock.
And if the crash was serious or anyone disputes how it happened, get qualified help quickly — not because a lawyer is magic, but because preserving this evidence means knowing who to write to before the shortest clock runs out.
What does your car know about you?
The book’s last chapter is the one an ordinary reader can act on today: what to ask before buying a car, and what to erase before trading one in.
Unpair every device. Delete stored destinations and navigation history — home, work, school, the addresses of people you care about. Remove connected-service accounts. Run whatever factory reset the vehicle offers, then check whether it cleared what you expected. Published forensic research has recovered location data and vehicle events going back months from a single infotainment drive.
Whatever your car has accumulated about where you go goes with it to the next owner, unless somebody clears it.
Frequently asked questions
Does every car have a black box?
No. The federal rule applies to covered vehicle classes manufactured on or after a specified date, and only if the vehicle is equipped with an event data recorder. It does not require every vehicle to have one.
How many seconds does an EDR record?
Historically five seconds of pre-crash data sampled twice per second for covered vehicles, with newer requirements phasing in a longer window. What a specific vehicle captured is a question of fact about that vehicle.
Does an EDR record audio or video?
No. The federal definition expressly excludes audio and video data. Dash camera footage is a separate source with separate retention.
Who owns the data in my car’s black box?
Federal statute makes data retained by an event data recorder the property of the vehicle’s owner or lessee, and restricts access by others subject to enumerated exceptions. That statute governs recorder data specifically — it does not decide ownership of infotainment records, telematics or manufacturer-server data.
Can black box data be erased or lost?
Yes. Records can be overwritten, never written at all if a trigger threshold was not met, or lost when a vehicle is repaired, salvaged or scrapped.
Do I need a lawyer to get vehicle data after a crash?
Retrieval can require specific tools, module access or cooperation that a vehicle owner may not have. The book’s position is to identify sources early and seek qualified help rather than attempt self-help extraction.
About Joseph Dedvukaj
Joseph Dedvukaj is a Michigan trial lawyer and founder of The Joseph Dedvukaj Firm, P.C., in Bloomfield Hills. For more than thirty years his practice has focused on representing people injured in automobile, commercial truck and motorcycle crashes. Your Car Is a Witness (Square Lake Press, 2026) examines what modern vehicles record, who can obtain it, how quickly it disappears, and what must be proved before anyone should believe what it says.
