ON the day when it was announced there would be no criminal prosecutions over the death of Sheku Bayoh, a high-profile lecture series concluded in Glasgow. The speaker was the influential philosopher Professor Judith Butler, and her topic was the philosophy of non-violence. Over the course of three evenings she set out her position that a defence of non-violence must be accompanied by a commitment to equality – that is, the notion that all lives are “grieve-able”; that all lives matter.

I doubt the American academic had heard the name Sheku Bayoh at the time she was preparing these lectures, but it was impossible not to think of him as she described some of the ways in which some lives are framed as worth preserving and safeguarding and some – the “others” – are not.

She spoke of black American victims of police brutality including Eric Garner, who died after being put into a chokehold by an officer in New York and repeating “I can’t breathe” 11 times; and Sandra Bland, who died in a jail cell in Texas days after being arrested during a traffic stop that ended with an officer attempting to drag her from her car then restraining her at the side of the road.

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Butler emphasised the importance of saying their names.

There can be few people in Scotland who have not heard the name Sheku Bayoh, and who would not recognise the smiling picture of the father-of-two that has accompanied so many column inches in the three-and-a-half years since his death in police custody. That one picture has been everywhere, but the words surrounding it have painted two very different pictures.

There is the loving partner, father, brother and son, who doted on his two boys and enjoyed socialising and going to the gym. And then there is the hulk, the brute, the drug-user who may have been wielding a knife. The maniac. The potential terrorist. The object to which “legitimate force” could be applied.

Force was applied to Sheku Bayoh when he was restrained by at least four police officers. When his body was examined he was found to have dozens of injuries, including numerous cuts to his face and a broken rib. He also sustained petechial haemorrhages in his eyes, which his family say point to positional asphyxiation – in other words, that the position in which he was held by police left him unable to breathe. A procurator fiscal’s report refers the “sudden death in a man intoxicated by MDMA (ecstasy) and alpha-Pyrrolidinopentiophenone (the drug Flakka) whilst being restrained”, but it still remains unclear what actually caused the death – the drugs, the restraint, or a combination of the two.

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Many other aspects of the case remain similarly unclear, and over the past three years a series of claims and counter-claims have been made by those involved that raise more troubling questions than they answer.

The Scottish Police Federation, which represents officers, has claimed that “a petit [sic] female police officer responding to a call of a man brandishing a knife was subject to a violent and unprovoked attack by a large male”, and that “the officer believed she was going to die as a result of this assault”.

By contrast Bayoh’s family and their lawyer, Aamer Anwar, point out that at 5’10” and 12 stone five pounds Sheku was in fact of average height and weight, and suggested racial stereotyping may have informed accounts suggesting he was “very large” and posed a deadly threat.

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Some reported have suggested at least two of the officers involved believed they may be faced with a terrorist – again suggesting Bayoh’s race was a factor in the police response – and relatives of one of the officers contacted the Bayoh family to allege that he was openly racist and had declared “I hate all blacks”.

Some may take the view that these factors do not matter. They may believe that since Bayoh’s behaviour was causing alarm, since he had taken drugs, since he may (although this is disputed) have at some point brandished a knife, the correct course of action was to restrain him.

The family do not dispute that police intervention was appropriate on that morning in May, and they have not sought to portray Bayoh as a saint. But they have raised serious questions about what exactly happened, whether the response was proportionate, and whether any lessons have been learned.

If, for even one of the officers involved in the restraint, Bayoh’s life did not register as what Butler calls “a life worth preserving” because of the colour of his skin, that would have massive implications. Could such a mindset be proven in a criminal court, and if it could, could a link be established between that belief and the outcome of the police response in 2015? It seems unlikely. But there can be no defending the latest indignity the family have suffered – learning of the Crown Office’s decision not to prosecute via a leak to a Sunday newspaper.

It goes without saying that the Bayoh family, and Sheku’s partner Colette Bell, deserve to know the truth, not only about his death but also about how the subsequent investigation was conducted. But the wider Scottish public need answers too. We depend on the police to protect us from harm – but who is the “us” worth protecting, and is there also a “them” who are seen only as a threat?