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About Mass Violence

Definitions of Mass Violence Crimes

There is no universal definition of mass violence crimes, mass murders or mass killings. Many different definitions are used by researchers, criminal justice experts, and public policy bodies. Some definitions focus solely on the number of deaths, but others count crimes in which there are few deaths but many injuries. Some definitions focus on the method used to kill and injure (e.g. firearms only) and others include crimes committed with any weapon. Some definitions focus on the perceived motive of the perpetrator (e.g. hate, terrorism, or a desire to kill strangers) or who was attacked (and do not count mass casualty crimes as mass violence if the perpetrator’s motive was to kill family members or rival gang members). Some definitions are designed to establish eligibility requirements to receive federal assistance after mass violence crimes.

There are three different definitions provided by the Federal government:

U.S. Congress

“The term ‘mass killings’ means three or more killings in a single incident” that occur in a ‘public place’.”

Investigative Assistance for Violent Crime Act of 2012; Public Law 112-265, 126 STAT. 2435 (2013): https://www.congress.gov/112/plaws/publ265/PLAW-112publ265.pdf

(The term) “mass shooting” is defined as a multiple homicide incident in which four or more victims are murdered with firearms, within one event, and in one or more locations in close proximity. Similarly, a “mass public shooting” is defined to mean a multiple homicide incident in which four or more victims are murdered with firearms, within one event, in at least one or more public locations, such as, a workplace, school, restaurant, house of worship, neighborhood, or other public setting.

Krouse & Richardson. (2015). “Mass Murder with Firearms: Incidents and Victims, 1999 – 2013. Washington, DC: Congressional Research Service https://fas.org/sgp/crs/misc/R44126.pdf

Federal Bureau of Investigation

According to the FBI, the term “mass murder” has been defined generally as a multiple homicide incident in which four or more victims are murdered, within one event, and in one or more locations in close geographical proximity. Note: the FBI definition appears to be designed on the basis of trying to identify profiles of perpetrators, so it excludes cases in which perpetrators kill family members unless large numbers of the general public are also killed. Likewise, cases in which killings occur as a part of another crime are excluded.

Krouse & Richardson. (2015). “Mass Murder with Firearms: Incidents and Victims, 1999 – 2013. Washington, DC: Congressional Research Service https://fas.org/sgp/crs/misc/R44126.pdf

U.S. Department of Justice, Office for Victims of Crime

Antiterrorism Emergency Assistance Program (AEAP)

AEAP guidelines define an act of mass violence as “an intentional violent crime that results in physical, emotional, or psychological injury to a sufficiently large number of people and significantly increases the burden of victim assistance and compensation for the responding jurisdiction, as determined by the OVC Director.” This definition is primarily designed to help OVC determine whether a mass violence incident is sufficiently large to indicate the possible need for federal assistance from OVC.

Office for Victims of Crime. (2016). “Office for Victims of Crime, Antiterrorism Emergency Assistance Program (AEAP) Brochure.” Washington, DC: U.S. Department of Justice, Office for Victims of Crime. https://www.ovc.gov/pdftxt/AEAP_Brochure.pdf

Conclusion

The lack of a consistent definition for mass violence can be confusing, and developing a more uniform definition would be helpful. However, the most important thing to remember irrespective of the definition used is that each mass violence incident leaves behind numerous victims and survivors who need assistance and support.