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 Wisconsin, assault is not specifically defined as a standalone crime; instead, the state uses the term 'battery' to refer to the physical act of harming someone or intending to harm them. However, Wisconsin does recognize actions that would be considered assault in other states under different terminology. For example, Wisconsin law considers 'disorderly conduct' as an offense that can include actions that put another person in fear of bodily harm, which aligns with the general concept of assault. Furthermore, Wisconsin statutes categorize battery against a law enforcement officer as a more serious offense. Under Wisconsin Statute 940.20(2), battery to a law enforcement officer, peace officer, or judge is a felony, reflecting the state's stance on the gravity of such offenses. The penalties for these offenses are more severe than for similar actions against a civilian, and the law provides for enhanced penalties when the victim is a public official performing their official duties.