The crime of assault varies from state to state (and under federal law), but is generally defined as intentionally putting another person in reasonable apprehension or fear of an imminent (immediate) harmful or offensive contact. The crime of assault may be committed even if there is no physical contact, as the criminal physical contact constitutes the separate crime of battery. In many states assaulting a police officer or peace officer who is performing official duties (such as making a lawful arrest) is a more serious offense—sometimes a felony.

In Arizona, assault is defined under Arizona Revised Statutes (ARS) §13-1203. Assault can occur in three primary ways: intentionally, knowingly, or recklessly causing any physical injury to another person; intentionally placing another person in reasonable apprehension of imminent physical injury; or knowingly touching another person with the intent to injure, insult, or provoke such person. The severity of the charge can range from a misdemeanor to a felony, depending on factors such as the seriousness of the injury, the use of a weapon, and the status of the victim. For instance, assaulting a police or peace officer, firefighter, teacher, healthcare provider, or prosecutor while they are performing their official duties is considered an aggravated assault under ARS §13-1204, which is a more serious offense and can be charged as a felony. This reflects the state's interest in protecting public servants and ensuring their safety while they are on duty.