It is only a defense some of the time to an accusation of statutory rape that the complainant lied about her age. In a charge of Contributing to the Delinquency of a Minor, or other crimes that depend on the victim being under 18, a defendant who believed the victim was older than she really was has a strong shot at acquittal.
But the rule is different if the crime was Rape III and the victim was under 16.
"163.325 Ignorance or mistake as a defense. (1) In any prosecution under ORS 163.355 to 163.445 in which the criminality of conduct depends on a child's being under the age of 16, it is no defense that the defendant did not know the child's age or that the defendant reasonably believed the child to be older than the age of 16."
What about the situation where the defendant makes a pass at a minor under 16, but she rebuffs him. The defendant is charged with attempted rape in the third degree. In support of an acquittal, can the defendant claim that he didn't know how old she was?
I think so. In fact, I think the argument is quite strong. It is in the attached motion and memo.
[/sites/default/files/ji-attempted-statutory-rape.doc JI Attempted Statutory Rape.]