This is a question I get asked fairly regularly. The answer is… It depends! The age of consent in Oregon is 18 — one of the highest in the nation. Thus, if you are an adult and had any kind of sex with someone who was 17, you can theoretically be prosecuted under ORS 163.415. Sexual abuse in the third degree — even if the age difference between you is just a few months. Here is the text of that statute:
(1) A person commits the crime of sexual abuse in the third degree if:
(a) The person subjects another person to sexual contact and:
(A) The victim does not consent to the sexual contact; or
(B) The victim is incapable of consent by reason of being under 18 years of age; or
(b) For the purpose of arousing or gratifying the sexual desire of the person or another person, the person intentionally propels any dangerous substance at a victim without the consent of the victim.
Sexual abuse in the third degree is a Class A misdemeanor, which means it is punishable by up to 1 year in jail, though probationary sentences are far, far more common.
In reality, there is not much risk of prosecution for this offense if you both teenagers– Oregon has an affirmative defense commonly referred to as the “Romeo and Juliet” defense which applies in a situation where the victim is 16 or 17, the sex is consensual, and the two individuals are less than 3 years apart in age. But, there is no “Romeo and Juliet” defense to some closely related crimes, like Recklessly Endangering Another Person, which could arise from unprotected sex, or Rape in the First Degree, which could arise if drugs or alcohol were involved. And if you are more than 3 years older, you have no defense, even if you reasonably believed the person was over the age of consent (for example, because they showed you a fake ID). In sum, it is best to proceed with a bit of caution before hooking up. Here are some potentially helpful resources: https://parentandteen.com/resources-about-sex/