In the fallout from the acquittal of Martyn Blake, the police firearms officer who stood trial for the murder of Chris Kaba, many questions have arisen. One of them is why the he was not charged with manslaughter.

The theory goes that it was always going to be difficult to get a jury to convict a police officer of the most serious form of homicide, whereas manslaughter may have been an easier to prove and more palatable option.

The argument appears to be supported by the fact that no police officer has ever been convicted of murdering a suspect and that the only time an officer has been found guilty over a death in the line of duty in the last 37 years was for manslaughter.

However, in that 2022 case, in which PC Benjamin Monk was convicted over the death of the former footballer Dalian Atkinson, the officer did not kill the former professional footballer with a firearm but used an electric stun gun on him and kicked him in the head as he lay on the ground.

Monk was convicted of unlawful act manslaughter, which is when death occurs as a result of a criminal act that a reasonable person would realise must have subjected the victim to at least some risk of harm. By contrast, a murder conviction requires intent to kill or cause grievous bodily harm. So, in the Monk case, the jury had to decide whether it was an unlawful act, and also the level of harm he intended to cause Atkinson or should have foreseen would have been inflicted on him.

While Blake said he did not intend to kill Kaba and told the court he aimed for his central body mass – the bullet actually struck Kaba in the head – it would be difficult to argue that the intent, when shooting someone, was not to cause grievous bodily harm, a difficulty that would extend to other cases involving police firearms officers.

The key issue in the Blake trial was therefore not the level of harm he intended to cause to Kaba but whether he acted lawfully, ie in self-defence, and to protect colleagues, as he had claimed in court.

If the jury felt that he had acted unlawfully, it would only have had to find that by firing at Kaba’s chest Blake intended to cause him grievous bodily harm to conclude that he was guilty of murder. As such, it seems unlikely that giving the jury the alternative option of unlawful act manslaughter would have made a difference.

After Blake gave evidence in his defence, the prosecution did ask the trial judge to offer the jury an alternative charge of manslaughter but Mr Justice Goss refused. Similarly, in the last murder trial of an armed officer, Tony Long, over the 2005 shooting of Azelle Rodney, the judge refused to allow the charge of manslaughter to be put before the jury alongside the more serious alleged offence.

A Crown Prosecution Service spokesperson said: “We presented the case on the basis that this was murder and that there was no realistic alternative. This is because our case was that the defendant used fatal force and therefore intended to kill or at the very least to cause serious harm and that he was not acting in lawful self-defence.”

They said Blake’s evidence that he did not intend to cause serious harm “raised the possibility that manslaughter could be left open to the jury” but this argument was rejected by Goss.