These ever-evolving machines are becoming standard equipment on new cars - an invaluable tool to law enforcement authorities, insurers and safety researchers, an increasing torment to lawyers and privacy advocates who see the boxes as silent police officers, always along for the ride.
Under current laws, auto manufacturers are not required to tell people whether their car has an EDR, which is similar to the "black box" on an airplane.
"It's a gold mine of potential data," said Anne McCartt, vice president of research for the Insurance Institute for Highway Safety, an industry group in Arlington, Va.
This month, state police charged Jensen, 37, of Wayne, with multiple offenses stemming from a Oct. 11 wreck that sent five people to hospitals and closed the westbound Schuylkill Expressway near Conshohocken.
Police said Jensen was impaired by amphetamines when she tore onto the shoulder, roared past slowing traffic, and smashed into a stopped state police cruiser, knocking it into other cars. Two troopers were among the injured.
At the hospital that night, Jensen told police she had no memory of the crash. But investigators thought they knew someone, or, rather, something that might. They got a search warrant to examine the EDR in Jensen's car.
Trooper Danea Alston, a state police spokeswoman and one of the first on the scene that night, said she could not discuss this specific case. But generally speaking, she said, "the black boxes have been very, very helpful."
An EDR can pinpoint a time or a speed that even an experienced accident investigator might have had to estimate. Drivers sometimes claim that their brakes failed, but, Alston said, "you can look at that box and say, 'Well, according to the machine, nothing failed.' "
