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 Kansas, the criminal offense of sexual assault of a child is addressed under the state's penal code as 'indecent liberties with a child' and 'aggravated indecent liberties with a child.' These offenses are defined in Kansas Statutes Annotated (K.S.A.) 21-5506 and 21-5507. The statutes criminalize various forms of sexual contact and intercourse with a person under the age of 16, which align with the actions described in points (1) through (5). It is important to note that Kansas law does not require the perpetrator to know the age of the child for the act to be considered a criminal offense. The severity of the charges and the penalties upon conviction can vary depending on the specific circumstances of the offense, including the age of the child and the nature of the sexual act. These crimes are considered serious offenses and can result in significant prison time and mandatory registration as a sex offender.