siveness in all geographic areas, and likelihood of being reported to law enforcement” (Federal Bureau of Investigation, 2004:2). Although the labels have changed slightly, the seven crimes identified by the 1927 IACP committee remain the focus of today’s Uniform Crime Reports and are known as “Part I offenses.” Three of these are crimes against persons—criminal homicide, forcible rape, and aggravated assault—and four are crimes against property: robbery, burglary, larceny-theft, and motor vehicle theft. The only substantive change to this list of Part I offenses was made in 1978, when legislation directed that arson be designated a Part I offense; however, arson continues to be reported on a separate form rather than the standard “Return A” used to report the other Part I offenses.

The Part I offenses are also known as “index crimes” because they are used to derive a general, national indicator of criminality—the national Crime Index. The index—first computed and reported in 1958—consists of the sum of the seven original Part I offenses, except that larceny is restricted to thefts of over $50.

The general order in which the Part I offenses are listed is not accidental. Instead, with some interleaving, the listing of offenses defines a strict hierarchy that agencies are asked to follow in coding offenses. In descending order, the UCR hierarchy by Part I offense and suboffense is as follows:

1. Criminal homicide

   1. Murder and nonnegligent manslaughter

   2. Manslaughter by negligence

2. Forcible rape

   1. Rape by force

   2. Attempts to commit forcible rape

3. Robbery

   1. Firearm

   2. Knife or cutting instrument

   3. Other dangerous weapon

   4. Strong-arm (hands, fists, feet, etc.)

4. Aggravated assault

   1. Firearm

   2. Knife or cutting instrument