AN OFFICER-INVOLVED SHOOTING (OIS) INCIDENT is defined by the Office of Community Policing Services  (COPS) in their report on the Philadelphia Police Department as any firearm discharge that meets the following criteria:

• The individual discharging the firearm is a sworn officer.
• The individual discharging the firearm may be on duty or off duty.
• The discharge of the firearm involves another human being.
• The discharge of the firearm is intentional (unless someone other than the officer is injured; discharges in which someone other than the officer is injured are also counted as OISs even if the discharge is accidental).

AN OFFICER-INVOLVED SHOOTING (OIS) RECONSTRUCTION is an area of crime scene reconstruction that concerns itself with a critical  examination of the circumstances and physical evidence associated with the shooting scene with the goal of establishing the most probable or likely sequence of  events relating to the shooting, while recognizing that other explanations may be possible.
It relies on an assessment of physical evidence from the scene as well as information obtained during the course of a medical, criminal and/or civil investigation.
Issues addressed during a shooting reconstruction may include:

• Shooter identification through GSR testing
• Position of the shooter
• Position of the victim or target
• Determination of bullet path
• Determination of bullet path deviations
• Determination of muzzle-to-target distance
• Determination of type of firearm used
• Link bullets and cartridge cases to firearms
• Cartridge case ejection patterns

These data sets are used to verify or refute an accounting of the incident by victim/s, shooter/s and/or witnesses.