Stop Unfair justice

My 22 year old black american son had a new years eve's party, had a few of his friends come over, they brought others. Everyone was viedo taping, rapping, drinking, druging etc. as the night went on they was wasted and my son had consented sex with a 15 year old white girl, there were several people in the room looking at this sexual act, someone was even video taping it, when it was brought to federal court they charge him with child pornography, and the the white girl who is now 19 went to court and testify in his defence and said she was not a victim, she felt my son was because they gave him 27 years and the judge thought he was being nice for just that many, he said if the young white girl had not wrote him a letter, my son would have got 30 to 50 years the punishment is too harsh and severe for what happen, a murderer gets less years or the same, there's no victim in my sons case, it's more like prejutive to me, A mother's cry please help chance this