A park-to-reverse defect is a scenario in which cars with automatic transmission can fail to properly engage the parking mechanism, causing the vehicle to unintentionally roll, sometimes resulting in injury or vehicular accidents.
This has significance in product liability law, and a number of major cases in the United States have been brought in which car manufacturers[1][2][3] were accused of negligence for not addressing an alleged dangerous flaw in the transmission.
[7] If the driver has exited the vehicle with the engine running (to for example retrieve an item, open a gate or close a garage door, etc.
[8] NHTSA (National Highway Traffic Safety Administration) refers to the "Park to Reverse" issue using various terms including "Unintended Powered Roll-Away" and has opened numerous investigations of these events over the last 35 years.
Because of the possible safety issue of this, and because driving a vehicle not fully in a gear over a long period of time could damage the transmission, automakers developed what is called the "detent system."
A case involving the death of a Los Angeles dockworker killed by a park-to-reverse defect in a Dodge Dakota.