If you rely on the FBI Uniform Crime Reports (UCR) for numbers of justifiable homicides, the numbers will always be significantly under reported. First, in many years, many states simply do not submit numbers, so they are not counted. Not all police jurisdictions in other states submit numbers, so the total is always going to be low.
The definition of justifiable homicides vary from state to state. What is reported is often politically determined.
Here is the FBI UCR definition for justifiable homicides, from pages 17 and 18 of the Uniform Crime Reporting Handbook:
Justifiable HomicideBy this definition, many justifiable homicides will never be reported to the FBI.
Certain willful killings must be classified as justifiable or excusable. In UCR, Justifiable Homicide is defined as and limited to:
• The killing of a felon by a peace officer in the line of duty.
• The killing of a felon, during the commission of a felony, by a private citizen.
NOTE: To submit offense data to the UCR Program, law enforcement agencies must report the willful (nonnegligent) killing of one individual by another, not the criminal liability of the person or persons involved.
The following scenarios illustrate incidents known to law enforcement that reporting agencies would consider Justifiable Homicide:
15. A police officer answered a bank alarm and surprised the robber coming out of the bank. The robber saw the responding officer and fired at him. The officer returned fire, killing the robber. The officer was charged in a court of record as a matter of routine in such cases.
16. When a gunman entered a store and attempted to rob the proprietor, the storekeeper shot and killed the felon.
NOTE: Justifiable homicide, by definition, occurs in conjunction with other offenses. Therefore, the crime being committed when the justifiable homicide took place must be reported as a separate offense. Reporting agencies should take care to ensure that they do not classify a killing as justifiable or excusable solely on the claims of self-defense or on the action of a coroner, prosecutor, grand jury, or court.
The following scenario illustrates an incident known to law enforcement that reporting agencies would not consider Justifiable Homicide:
17. While playing cards, two men got into an argument. The first man attacked the second with a broken bottle. The second man pulled a gun and killed his attacker. The police arrested the shooter; he claimed self-defense.