Motor vehicle collisions can be the center of attention in both criminal cases and civil cases. In order for a judge or jury to determine fault or liability for a collision, it is first necessary to determine how the collision occurred. Three sources of information can be used by the court to make this determination:

1. The testimony of witnesses who observed the accident.

2. The examination of physical evidence, such as photographs of the collision scene taken by police officers.

3. The testimony of accident reconstruction experts.

Vehicular accident reconstruction is the scientific process of examining all of the relative data derived from an accident. This data includes police measurement of skid marks and detailed photographs of the damaged automobile parts, weather and roadway conditions. Accident reconstruction experts often have a background in engineering or physics. They analyze the gathered data, and conduct an in-depth analysis to determine the cause or causes of the collision and any contributing factors. They use principles of physics and engineering such as the conservation of momentum, coefficient of friction and other principles to try to “reconstruct” how the accident occurred, including the speed and direction of the vehicles at the moment of the collision. They often use specialized software in the process.

These conclusions are then presented at trial when the accident reconstructionist testifies as an expert witness.