
A couple of years back, I can remember being in a car accident where 100% liability fell to the other driver. At the time, it was next to impossible prove liability and the case dragged on for a while. There were no independent eye witnesses and it was only after the adjusters took a look at impact damage on both vehicles did they access full liability to the other driver.
If, at the time, I had a T-Eye ADR3000 installed in my vehicle, there would be absolutely no question regarding liability. This car gadget records both audio and video in a continuous loop. If the vehicle is ever in an accident, the footage is marked and stored for later viewing.

In addition to audio/video footage, captured data will also include GPS information such as vehicle speed, location, direction of travel, and the state the vehicle was in when the accident happened (eg accelerating or not). All this information can also be superimposed onto Google Maps, giving you an exceptional, independent eyewitness.
[T-Eye ADR3000 via Red Ferret]