Liam Joseph stepped out of the Nisa convenience store on Deptford High Street. He met his brother, Dijon, who had just ordered some food from the takeaway next door, and they tapped fists. Within seconds Dijon’s arm was grabbed by an officer from the Met’s territorial support group who said she saw them exchanging drugs.

As Dijon protested, another officer tightly cuffed his free wrist and accused him of behaving aggressively. “I’m not being aggressive … I’m a big guy,” said Dijon, who is 6ft 8in tall.

“Exactly,” the officer replied. At the same time, another officer restrained Liam, while a second rifled his pockets. Finding nothing illicit, the officer took his keys and searched his car.

The incident is now under investigation by the Independent Office for Police Conduct. The Josephs, neither of whom has a history of drug-taking or violent crime, have alleged that it was a clear case of racial profiling, there were no reasonable grounds for a search, and that officers used unnecessary force. If the police are exonerated, it suggests an act as commonplace as a fist bump can justify a stop and search – at least if the suspect is black.

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Dijon shared footage of the 27 February incident on Facebook, where it has been viewed more than 200,000 times. His video ends as officers, finding his girlfriend’s bank card in his wallet, arrest him for handling stolen goods.

Eventually, they were forced to release him at the scene after speaking to her on the phone. Finally, having detained the brothers for about 40 minutes, they left – with no apology, no explanation and no paperwork.

David Lammy, the Labour MP for Tottenham, who last year conducted a review of racial disproportionality in the justice system, said the incident was typical of the way police treat black men.

Dijon Joseph’s video of the stop and search incident involving him and his brother, Liam, on 27 February in Deptford, south-east London.

The incident coincided with a political row over stop and search and a violent crimewave in the capital that has led to calls for increased use of the power – but black politicians, police and community leaders have warned that overuse of the tactic damages trust.

“This is an exemplary case of the hugely damaging impact that stopping and searching innocent young men can have in driving a wedge between the police and the communities they serve,” Lammy said.

Dijon said that the incident was merely the latest in a string of difficult interactions he has had with police. “There was no dialogue,” he said. “There was no attempt to get our attention whatsoever, and it shouldn’t be that way.”

He works as a youth mentor, and he said it made it hard for him to continue to advise that police were well intentioned.

Liam, a professional musician, said he was used to stop and search, but that this incident was different.

“I felt ashamed, and I felt disrespected and I felt threatened; and it felt like it was a toe-to-toe situation,” he said, explaining that he feared police would become more violent. “The whole time, in the back of my mind, I was watching them to, if necessary, get ready to weave to the left or the right to protect myself.”

“I do want an apology,” Dijon said. “They know what they’ve done on the day, they know how they treated us; they know they profiled us … how can I make them understand that people do look like me – they are tall, they are black, and they have dreads and they have deep voices – but we’re good people.”