Fact: An EDR records only certain information

Click to enlarge pictureRamtron Event Data Recorder (© Ramtron International)

Ramtron Event Data Recorder

In addition to the date and time when triggered, the data that EDRs collect include vehicle speed, engine speed, steering angle, throttle position, braking status, force of impact, seat-belt status and airbag deployment. It cannot tell who was driving and where. It can't tell if the driver was intoxicated, violating a traffic law or using a cell phone.

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Fiction: Service technicians at dealerships have access to EDR data

When you bring your car in for service, a technician can theoretically access the data on an EDR, although it's highly unlikely. While service techs routinely access data about a vehicle through the onboard diagnostic port, they would need special tools and software to tap into an EDR. "Normally, when automotive technicians service a vehicle, they don't access the black-box data that an accident investigator or police department personnel would," Hutchison says.

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Fact: Specialized training is required to extract and analyze EDR data

Even if a service tech does access a vehicle's EDR, extracting the data requires the proper diagnostic tools, and specialized software and training are required to properly analyze the data. "You can hook into the data link port, but you have to have specific modules and cables and the software to be able to read the information from the EDR to get pre-crash data," Hutchison says. "And you have to know what you're looking for and know how it applies to a particular accident."

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Fiction: EDR data can be accessed without your consent

"For the most part, EDR access is very much a matter of state law," says Dorothy Glancy, professor of law at Santa Clara University School of Law in California. Federal legislation is pending that would make this a legal standard nationwide. However, the proposed law would allow emergency personnel such as police, firefighters and paramedics access to the data without a court order if it helps them better respond to an accident.

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Fact: EDR data can be accessed by court order

Currently, several states have statutes that regulate who owns the data from a car's black box and who can gain access to it. In many states, a warrant is required to access the data without the owner's consent. But as with any law, exceptions exist and a court order can be used to force a car owner to hand over black-box data in legal proceedings. "We either need the permission of the owner of the vehicle or get a subpoena through the courts to get access to the data," says Buddy Oakes, an insurance agent in Columbia, Tenn. "It's not something that happens every day. It probably comes up two or three times a year, but we're a small regional insurance company." One potential loophole: When a car is totaled, it becomes the property of the driver's auto insurance company. The insurer then owns the data and could possibly use them as evidence in a court case.

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Fiction: EDR data can conclusively prove fault in a court case

While EDR data is valuable in reconstructing an accident for investigators, they don't provide conclusive evidence. "I'll first do an accident reconstruction at the scene to see what types of forces were involved in a collision and what types of evasive action was taken or not taken, and how far the vehicles went after the collision," Hutchison says. "So you can use the scene data to determine what happened and how it happened." But not why it happened.

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Fact: EDR data is only part of the puzzle in an accident

"The physical aspects of the accident have to match up with the data from the EDR," Oakes says. "Usually it does. But there could be situations where it doesn't. And the [EDR data] isn't something we would put a lot of weight into at that point if the physical damage doesn't look right."

It can also be used in "he said, she said" situations, according to Oakes. "That's where it works best," he says, "when someone says they were sitting at a red light and somebody hit them. Then we'll look at the black-box data and find out they were going 30 mph and braked right before impact."

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Doug Newcomb has been writing about automotive-related topics since 1988. His work has appeared in Consumers Digest, Road & Track, Rolling Stone, Men's Journal and many other publications. His book, Car Audio for Dummies, is available from Wiley Publishing.

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