I answered a question on Quora this weekend about an apparent discrepancy in U.S. homicide statistics reported by the United Nations versus those provided by the FBI. The UN Organization on Drugs and Crime (UNODC) appears to report higher homicide rates in the U.S. than what’s reported in the FBI’s Uniform Crime Report.
For example, for 2011 UNODC reported 14,748 homicides in the U.S., while the FBI reported 14,612, a difference of 136 fewer murders reported by the FBI. FBI data does exclude justifiable homicides, which it defines as the “killing of a felon by a police officer in the line of duty,” or the “killing of a felon, during the commission of a felony, by a private citizen.”
However, both UNODC and the FBI define homicide similarly, so that in itself is probably not the culprit. The FBI defines murder and nonnegligent manslaughter as “the willful (nonnegligent) killing of one human being by another.” UNODC uses “unlawful death purposefully inflicted on a person by another person,” excluding deaths caused by armed conflict (war, for example) as its definition.
The more likely source of the discrepancy is that FBI data does not include information from public health sources, while the UNODC numbers do include such information, in addition to that received from criminal justice agencies.
What we may be seeing in the different reporting, then, is the influence of that public health data. Public health agencies may be detecting and reporting what they believe to be “homicides” under the UNODC criteria, but some of those cases may be considered “justifiable” (and not reported) under FBI criteria.
Of this, the UNODC says, “Data included in deaths by cause datasets produced by WHO [World Health Organization], though based on national data, are to some extent adjusted or estimated to ensure a greater degree of completeness and international comparability.” So, we may be seeing some slippage in definition of the terms “unlawful” in the UNODC data set.
Also, as it turns out, the FBI’s data on justifiable homicides may be incomplete, which might be further contributing to the observed differences. Public health agencies may view a death as “unlawful,” for example, and report it to UNODC, while local law enforcement (who are the ones that provide data for FBI crime statistics) may view it as ambiguous and report it in the justifiable category.
There may be other factors driving these inconsistencies, so always make sure to carefully evaluate the methodology behind these types of statistics before arriving at any conclusions about what they may actually mean in practice.