A person generally commits the criminal offense of sexual assault of a child—regardless of whether the person knows the age of the child at the time of the offense—if the person (1) causes the penetration of the anus or sexual organ of a child by any means; (2) causes the penetration of the mouth of a child by the sexual organ of the person; (3) causes the sexual organ of the child to contact or penetrate the mouth, anus, or sexual organ of the person or another person; (4) causes the anus of a child to contact the mouth, anus, or sexual organ of the person or another person; or (5) causes the mouth of a child to contact the anus or sexual organ of the person or another person.

The naming and definition of the criminal offense of sexual assault of a child varies from state to state. These criminal offenses are generally located in a state’s statutes—often in the penal or criminal code.

In Wisconsin, the criminal offense of sexual assault of a child is defined under Chapter 948 of the Wisconsin Statutes, specifically sections 948.02 and 948.025. The law states that any adult who has sexual contact or sexual intercourse with a person who has not attained the age of 16 years is guilty of a Class C or Class B felony, depending on the circumstances of the case. The statutes cover various acts of sexual assault, including those listed in the provided description, such as penetration of the anus or sexual organ of a child, contact involving the mouth and the sexual organs, and other forms of sexual contact. It is important to note that in Wisconsin, the offender's knowledge of the child's age is not a defense to a charge of sexual assault of a child. The law is designed to protect minors from sexual exploitation and abuse, and it imposes severe penalties on those who commit such offenses against children.