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 Colorado, the criminal offense of sexual assault on a child is defined under Colorado Revised Statutes Title 18 Criminal Code, Article 3, Part 4. The law states that any actor who knowingly subjects another not his or her spouse to any sexual contact commits sexual assault on a child if the victim is less than fifteen years of age and the actor is at least four years older than the victim. Sexual contact is defined as the touching of the victim's intimate parts by the actor, or of the actor's intimate parts by the victim, or the touching of the clothing covering the immediate area of the victim's or actor's intimate parts. The law does not require knowledge of the child's age as a defense, and the offenses can include any of the actions described in the provided topic description. Convictions for sexual assault on a child can result in severe penalties, including imprisonment and mandatory registration as a sex offender. Enhanced penalties may apply if the offense is a part of a pattern of sexual abuse or if it includes aggravating factors.