As protesters gathered outside Georgia supreme court on Wednesday, holding candles and singing We Shall Overcome, Marcus Dixon's lawyers were arguing to appeal judges that his punishment was unusually harsh.

"If the young lady was black and Marcus Dixon was white, I don't think we would be here," said Joseph Lowery, one of the founding members of the Southern Christian Leadership Council.

Dixon was 18 when he had sex with the girl, who was three months short of her 16th birthday. He claims the encounter last February was initiated by the girl.

"I said we should go to my house, that there was no one there," he said. "But she said she was afraid someone would see us leaving together. She said that her daddy was a racist and that he would kill both of us if he knew she was with a black man."

The girl accused Dixon of raping her, saying he attacked her while she cleaned an empty classroom, bruising her arms and cutting her lip.

Dixon said he used a condom and threw it away. Investigators said they did not look for the condom because they were certain he was not telling the truth. "I didn't believe him," an investigator said.

The jury of nine whites and three blacks decided the sex was consensual and acquitted him of rape, sexual battery, aggravated assault and false imprisonment.

But because the girl was under 16, the jury found him guilty of the lesser charge of statutory rape and, because of her injuries, the more serious charge of aggravated child molestation. Child molestation was categorised as one of the "seven deadly sins" by Georgia's legislators when they toughened sentencing guide lines in 1995 and carries a minimum 10-year sentence.

Five of the jurors have since said that if they had known the sentence would be so harsh they would never have convicted him.

Those who support Dixon argue that the minimum sentencing is both unfair and cruel and has been misapplied. "You have this one-size-fits-all type of sentencing," said Marc Mauer of the Washington-based Sentencing Project. "No two cases are alike, no two victims are alike."

Civil rights activists also argue that Dixon has been punished for transgressing the old racial boundary of black men sleeping with white women in a judicial system heavily weighted against African-Americans. Black teenagers are also nine times more likely to be jailed for violent crimes than whites.

"Marcus's case brings back memories of all the black men who were lynched, executed or imprisoned for having relationships with white women," wrote Marian Wright Edel man, president of the advocacy group Children's Defence Fund in the Los Angeles Times yesterday. "And it recalls the way black males are perceived to this day."

District attorney Leigh Patterson denies the accusation. Dixon, a star athlete who had a college place before he was sent to jail, had twice before been reprimanded for inappropriate sexual behaviour in school. "We believe her story. We believe she was raped," said Mr Patterson. "This is not about race. This is about a sexual predator."

The issue of race is further complicated by the fact that Dixon's legal guardians are white. With his mother in jail and his father gone, he was being raised by his grandmother when Kenneth and Peri Jones adopted him aged nine. The child's arrival split the Jones family when Mr Jones's mother moved out of the house and he stopped speaking to his brother, who refused to accept the boy.

The Jones family have spent their life savings on Dixon's defence and insist he has always made them proud. "Marcus would never hurt a fly," said Mrs Jones. "He may have committed a sin. But he never committed a crime."