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.

The crime of assault with a deadly weapon (also known as aggravated assault) occurs when someone uses a deadly weapon (gun, knife, club, tire iron, brass knuckles, etc.) during an assault.

In Maine, assault is defined under Title 17-A, §207 of the Maine Criminal Code as intentionally, knowingly, or recklessly causing bodily injury or offensive physical contact to another person. The state differentiates between simple assault and aggravated assault. Aggravated assault, which may be referred to as assault with a deadly weapon, is a more serious offense and is covered under Title 17-A, §208. This occurs when a person intentionally, knowingly, or recklessly causes serious bodily injury to another, uses a weapon to inflict bodily injury, or assaults a person under certain aggravating circumstances, such as if the victim is pregnant or if the assault is against a child under six years old. The use of a deadly weapon during an assault elevates the crime to aggravated assault, which is a felony, whereas simple assault is generally a misdemeanor. It is important to note that the mere fear of harm, without physical contact, can constitute assault in Maine, while physical contact is typically required for a battery charge, which is not a separate offense in Maine but is included within the assault statutes.