Illinois Uniform Crime Reporting (IUCR) codes are four digit codes that law enforcement agencies use to classify criminal incidents when taking and filing individual reports.

IUCR codes are also used to aggregate types of cases for statistical purposes. In Illinois, the Illinois State Police establish IUCR codes, but the agencies can add codes to suit their individual needs. The Chicago Police Department currently uses more than 350 IUCR codes to classify criminal offenses, divided into “Index” and “Non-Index” offenses.

Index offenses are the offenses that are collected nation-wide by the Federal Bureaus of Investigation’s Uniform Crime Reports program to document crime trends over time (data released semi-annually), and include murder, criminal sexual assault, robbery, aggravated assault & battery, burglary, theft, motor vehicle theft, and arson. Non-index offenses are all other types of criminal incidents, including vandalism, weapons violations, public peace violations, etc.