Yasmin Alibhai-Brown: The US is showing how to protest with dignity

Trayvon Martin smiles at the camera, a neat boy with nice teeth, wearing a red Hollister tee-shirt, 17 and black, who looks, says President Obama, like a son he might have had. Martin will be forever young, globally famous, though for something he would not have chosen. He went out to buy an iced tea and sweets from a convenience store in Florida and was shot dead by 28-year-old George Zimmerman, a large, Hispanic/white volunteer with a neighbourhood watch.

African-Americans have taken to the streets across the US – civil rights defenders from the National Association for the Advancement of Coloured People, and career marchers Al Sharpton and Jesse Jackson, their eyes hazy but still angry. The teenager, they say was killed simply for "walking while black".

Watching the events unfold, I wonder why we can't galvanise such protests when similar cases happen in the UK? We used to, long, long ago. I wore out many pairs of special demo shoes with padded inner soles. This was back in the 1980s when thousands of us marched on police stations where officers had maltreated black suspects or ignored their unlawful deaths. The last time we saw such massive outrage was when Stephen Lawrence was stabbed to death. That led to a major inquiry.

Now we seem utterly hopeless, reacting with fatalism or with stupendous nihilism. Mark Duggan, mixed race and known to the police, was shot dead last year, triggering riots across England. Rioters soon forgot Duggan, captivated as they were with goods. Meanwhile, last week a black man from London's East End recorded his treatment in a police van, physical assaults and racist abuse. If people were aroused and came out, they would stop such failures of accountability and possibly change behaviours.

I am not suggesting demonstrators should only follow police actions. Black American activists are also targetting Zimmerman's alleged racism. Here, a beautiful five-year-old Asian girl, Thusha Kamaleswaran, who wanted to be a dancer, was shot and paralysed in a relative's shop by black gang members. To date, good black folk have not walked the streets to condemn the thugs.

There has been much pessimism about the effectiveness of public protests since anti-war marchers were ignored by Bush and Blair, and the contemptuous disregard shown by the Coalition towards professionals objecting to their NHS and Education policies. But collective activism is still worth it. At some junctures, it speaks up for virtue and integrity and reminds institutions of their responsibilities. We should learn from the US and rise up more, and more effectively.