Legal Definitions - ballistics

Ballistics is the scientific study of the motion, behavior, and effects of projectiles, such as bullets, rockets, or shells. In a legal context, it primarily refers to the forensic examination of firearms, ammunition, and related evidence to determine facts in criminal investigations.

This field helps investigators understand how a firearm operates, what type of ammunition was used, and how a bullet traveled from the gun to its target. By analyzing unique marks left on bullets and cartridge casings, experts can often link a specific weapon to a crime.

• Example 1: Linking a Firearm to a Crime

  After a robbery, police recover a bullet from a wall at the crime scene. They later apprehend a suspect and find a handgun in their possession. A ballistics expert would then test-fire the suspect's handgun into a water tank to obtain comparison bullets. By examining the microscopic scratches and imperfections (known as striations) left on both the crime scene bullet and the test-fired bullets, the expert can determine if they were fired from the same weapon. This illustrates how ballistics is used to forensically identify if a specific firearm was used in a particular incident.

• Example 2: Reconstructing a Shooting Scene

  During an investigation into a shooting, bullet holes are found in a car door, a nearby fence, and a tree. A ballistics expert can analyze the angles and entry points of these bullet holes to determine the trajectory (path) of the bullets. By mapping these trajectories, they can estimate the approximate position of the shooter, the direction of fire, and potentially the sequence of shots. This demonstrates how ballistics helps reconstruct the events of a shooting by analyzing the movement and impact of projectiles.

• Example 3: Identifying Ammunition Type and Weapon Functionality

  Investigators recover several spent cartridge casings at a crime scene, but no firearm. A ballistics expert examines these casings to identify their caliber, manufacturer, and any unique marks left by the firing pin, ejector, or extractor of the weapon. This analysis can help determine the type of firearm that was likely used (e.g., a 9mm pistol, a .22 caliber rifle) and whether it was functioning properly at the time of the shooting. This shows how ballistics involves studying ammunition characteristics and firearm mechanics to narrow down potential weapons or understand their operational state.