The National Guard was unleashed on Baltimore yesterday to quell unrest following the funeral of 25-year-old Freddie Gray, who died of injuries sustained in police custody. On 12 April, Gray was pinned to the pavement by officers before being loaded into a police van. When he was taken out of it his spine was ‘80 per cent severed’, according to the family’s lawyer. He spent a week in a coma and died on 19 April.

On Saturday I went to join a protest due to start at the corner of Presbury and North Mount streets. On my way there from the subway station I passed an alleyway with four police cars in it, their lights flashing. The cops appeared to be questioning people. A group of residents, all black, stood at the entrance to the alley, their phone cameras trained on the police.

I asked what was going on. ‘This shit happens every day around here.’ When a fifth police car arrived, a few members of the group put their hands sarcastically in the air. One man told the officer at the wheel that the alleyway couldn’t accommodate any more police vehicles.

Phone footage can occasionally force the police to be accountable, as in the case of Walter Scott, an unarmed black man shot several times in the back by an officer in South Carolina.

Gray’s arrest was captured on film too, but only up until the moment he was shoved into the van. His crime had been to flee the police unprovoked in a ‘high-crime area’ – a.k.a. ‘running while black’.

Given the cops’ track record, it’s hardly surprising people run from them. Technically it doesn’t count as probable cause for arrest, but the Supreme Court has determined that the fourth amendment protecting against arbitrary detention doesn’t necessarily apply in ‘high-crime areas’.

The court hasn’t defined, however, what these areas are. According to a 2008 article in the American University Law Review,

There is no agreement on what a ‘high-crime area’ is, whether it has geographic boundaries, whether it changes over time, whether it is different in different parts of the country, whether there are different types of ‘high-crime areas,’ or who determines that an area is, in fact, a higher crime area.

Meanwhile, the ability to designate high-crime areas encourages the police to commit crimes in them. Last September, the Baltimore Sun reported that the city had paid out $5.7 million since 2011 in police abuse lawsuits. There was a state of emergency in Baltimore long before it was declared yesterday.