None of us know what happened exactly, other than the 18 year old boy had sex with the 15 year old girl, and she told her parents she was raped. They did not have a personal relationship before or after the incident. Even if it was a "he said/she said" situation where the girl changed her mind, this is in no way one of the young man's finer moments. He outweighed her by 100 pounds, and there should be a significant maturity difference between the two (because of the age difference) that makes the act very unseemly. It still wouldn't reflect well on the young man if they were at similar maturity levels.
If there were no racial issues (both black or both white), this would reflect just the same on the young man. Maybe he shouldn't have gone to jail, but there are greater justice issues to be concerned about than this, in my opinion.
I see Romeo/Juliet laws mentioned. Aren't they supposed to apply to youths that are in relationships, and not hook-ups (which is the description of this event that is kindest to the young man)?