However, this number is nearly arbitrary, as the law permits individuals aged 14 and 15 to consent to sex with anyone younger than 18.Thus, despite the age of majority, a 15-year-old and 17-year-old could legally have sex in Indiana, but if the older person were 18, it would be a crime. Indiana takes a few notable deviations from standard age of consent laws.
However, the offense is a Class A felony if: (1) it is committed by using or threatening the use of deadly force; (2) it is committed while armed with a deadly weapon; or (3) the commission of the offense is facilitated by furnishing the victim, without the victim’s knowledge, with a drug (as defined in IC 16-42-19-2(1)) or a controlled substance (as defined in IC 35-48-1-9) or knowing that the victim was furnished with the drug or controlled substance without the victim’s knowledge.
"Sexual conduct" means sexual intercourse, deviate sexual conduct, exhibition of the uncovered genitals intended to satisfy or arouse the sexual desires of any person, sado-masochistic abuse, sexual intercourse or deviate sexual conduct with an animal, or any fondling or touching of a child by another person or of another person by a child intended to arouse or satisfy the sexual desires of either the child or the other person.
IC 35-42-4-4 Child exploitation; possession of child pornography; violation classification; exemption; definitions Sec. (a) As used in this section: "Disseminate" means to transfer possession for free or for a consideration. "Performance" has the same meaning as in IC 35-49-1-7. (c) A person eighteen (18) years of age or older who knowingly or intentionally: (1) engages in sexual intercourse; (2) engages in deviate sexual conduct; or (3) touches or fondles the person’s own body; in the presence of a child less than fourteen (14) years of age with the intent to arouse or satisfy the sexual desires of the child or the older person commits performing sexual conduct in the presence of a minor, a Class D felony.
Technically, this "close-in-age" provision is a defense instead of an exception, but it allows a 4 year gap in age if the two are in an ongoing personal relationship.
Thus, ostensibly, a an 18-year-old could avoid prosecution for having sex with a 14-year-old, provided the two were in an ongoing romantic relationship as defined by Indiana law.