On Tuesday 7 January Darrin Manning, 16, emerged from the Philadelphia subway with his high school basketball team-mates on their way to a game. With the region in the grip of the polar vortex it was viciously cold – so harsh their principal had given them hats, gloves and scarves to wear. The youngsters say they saw a police officer "staring them down" and Manning says one of them "may have said something smart". The police say they saw a dozen young men running in "ski masks". The police gave chase; the young men ran. Manning stopped running thinking it implied guilt. "I didn't do anything wrong." He was first tackled to the ground by several police and then frisked by a female officer with such ferocity that he ended up in hospital with a ruptured testicle.
"She patted me down again, and then I felt her reach, and she grabbed my butt," said Manning, who was universally described among media outlets as "a straight-A student" or "a model student". "And then she grabbed and squeezed again and pulled down. And that's when I heard something pop, like I felt it pop."
Manning says prior to the alleged sexual assault he was roughed up by several officers and hit with handcuffs. Police claim he hit an officer several times, without inflicting any injury, and "didn't complain of any pain", while being charged with assaulting an officer, resisting arrest and reckless endangerment.
Eyewitnesses quoted in the Philadelphia Inquirer confirmed Manning's account of excessive force. The next day Manning underwent emergency surgery. It remains to be seen whether he will ever be able to father children. Last week police decided to proceed with his prosecution.
Until now the emasculation of the black male at the hands of the modern American state has been just a metaphor. In this instance, however, it's literal. The incident raises many issues. Why should wearing ski masks (which they weren't) in the freezing cold be a police matter? If this is what happens to those who stop for the police why wouldn't a parent advise their child to run? The mass incarceration and routine criminalisation of young black men in the US is not a statistical aberration but a systemic abomination. It currently has more people in its penal system than the Soviet Union did at the height of the gulag. It says a great deal about the low expectations African Americans have of those charged to protect them that Manning's mother said: "I'm just grateful that they didn't just kill him."
But for now I want to concentrate on just one issue: the almost obsessive emphasis on Manning's academic achievements and "clean record". The desire is not just to establish his essential decency in the face of such unfair treatment but to counterpose the two as though such a demeaning thing should not happen to such a promising young man. For implicit in the framing of this idea is the belief that this incident is only worthy of our outrage because Manning is a victim worthy of our sympathy. It suggests that there's a worse grade out there he might have got, or a criminal past, that might justify this incident. As his mother pointed out: "They shouldn't be able to do that to any child."
It's not a point limited to race. Rapes and sexual assaults are qualified by the behaviour and attire of the woman; acts of torture are weighed against the prisoner's history of religious extremism or terrorism; benefit cuts are justified on the basis of whether the poor are "deserving" or not. The horror of the injustice is calibrated against the honour of the victim.
Campaigners for the victims often buy into this for strategic reasons: establishing their good character accentuates the obscenity of the crime. But ultimately it also limits the campaigns to the rights of an individual, rather than the broader principle on which those rights are based, by accepting a morality play crafted by those who do not have those principles at heart.
It suggests that sexually active women, terrorists or C-grade students had it coming to them rather than that women have the right to wear what they want free of harassment; nobody, including terrorists, should be tortured; or that high school dropouts and ex-convicts have the right to walk the streets unmolested.
When that terrain is conceded the argument moves from "this shouldn't happen to anybody" to "it shouldn't have happened to this person because they are a somebody"; from "I can't believe they're treating black people like this" to "I can't believe they're treating a black A-student like other black kids".
The contradiction was evident several years ago, when the radio shockjock Don Imus lost his show for referring to the Rutgers women's basketball team as a bunch of "nappy-headed ho's". When asked about the difference between Imus's comments and his own misogynist rap lyrics, the rapper Snoop Dogg answered: "It's a completely different scenario … [Rappers] are not talking about collegiate basketball girls who have made it to the next level in education and sports. We're talking about ho's that's in the 'hood that ain't doing shit."
It's the logic that allowed a large section of Britain to dismiss both the shooting of an unarmed Mark Duggan in London and then the misleading of the public, because of Duggan's "criminal record" and "criminal connections". "Duggan was a gangster not Nelson Mandela," wrote the Daily Mail's Richard Littlejohn, ignoring the fact that even if he was, he would still be entitled to a fair trial rather than summary execution.
This is less of an esoteric point than it might first appear. A study last week revealed that almost 50% of black men in the US under the age of 23 have been arrested; that's roughly the same percentage as black boys who fail to graduate with their appropriate year group. Meanwhile, almost one in 10 young black men are behind bars. Born in the poorest areas, herded into the worst schools, policed, judged and sentenced in the most discriminatory fashion, by the time African American men reach manhood the odds have been heavily stacked against them. Many have less than stellar credentials. That does not give the state the right to strip them of their manhood or deprive them of their human rights and dignity.
• This article was amended on 28 January 2013. It originally referred to the Philadelphia Enquirer. It is the Philadelphia Inquirer. This has been corrected.