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 Oregon, the criminal offense of sexual assault of a child is addressed under the state's statutes concerning sexual offenses involving minors. Specifically, Oregon law defines various degrees of sexual abuse, which include acts similar to those described in the query. For instance, Sexual Abuse in the First Degree (ORS 163.427) can involve a victim who is under the age of 14 and includes acts of sexual contact or penetration as described. Lack of knowledge of the child's age is not a defense to these charges. The law is designed to protect minors from sexual exploitation and abuse, and convictions for such offenses can result in severe penalties, including imprisonment, fines, and mandatory registration as a sex offender. It is important to note that the specific charges and penalties can vary depending on the circumstances of the offense, including the age of the child and the nature of the act.