An accident is often caused by the actions of more than one driver, like when a drunk driver pulls out in front of another driver who's speeding. This becomes a case of "comparative negligence", where it often becomes a matter of who was legally "more" at fault.

The accident reconstructionist must also deal with fraudulent accidents, usually involving what we at FACTS refer to as "rear-ender-fender-benders". Sometimes the collisions are staged, but more often the fraud simply involves seizing the opportunity of a real collision to claim non-existent or exaggerated injuries.

Accident reconstruction involves accidents of many flavors, not just vehicular mishaps.

[If the bulb hasn't been too badly damaged, it's often possible to determine whether a light was functioning and ON at the moment of impact.

In the rear signal bulb at left, the arrow indicates the bulb's tungsten filament, which was twisted and distorted from a severe and fatal rear impact.

The distortion is conclusive evidence of incandescence, since the filament becomes ductile and stretchable only when heated. A cold filament typically breaks without significant stretching during such an impact, a condition known as "cold shock".]