It follows a change in the law in June that raised the burden of proof for gross misconduct.

A jury had cleared Sergeant Martyn Blake of murder, after he fired on Mr Kaba while stopping a car he was driving.

The Metropolitan force is welcoming the watchdog’s decision.

IOPC Director of Engagement Amanda Rowe said: “Our thoughts remain with Chris Kaba’s family and friends and everyone impacted by his death.

“We are acutely aware of the impact of proceedings for everyone involved in this case and have always sought to avoid any unnecessary delays, however it was right that we paused progressing disciplinary proceedings until the legislation change came into effect and its impact was clear.

“Having considered both our policy and the representations from the Kaba family and Sergeant Blake, we have today notified them of our decision to withdraw disciplinary proceedings.”

We have also notified HM Coroner of this decision, who had paused consideration of whether to re-open the inquest while disciplinary matters remained outstanding.

Commissioner Sir Mark Rowley said: “Today’s decision finally brings to an end almost four years of uncertainty for NX121, his family and the wider firearms command, with all the considerable worry and stress that has brought. We also recognise the profound impact on Chris Kaba’s family, who continue to grieve their loss.

“Since NX121’s unanimous acquittal by an Old Bailey jury, and in the absence of any evidence that he failed in his duties, we have been clear and consistent in our view that he should not face a misconduct hearing.
“Our armed officers respond to more than 4,000 incidents each year, but there are only one or two incidents where shots are fired by police. It is undeniable that they are the most professional, most accountable and most cautious in their use of lethal force in the world.

“The IOPC has now reconsidered NX121’s case in light of the recent change in the law, and we welcome this sensible decision.

“But this must be a milestone moment to reset a police accountability system that is out of balance.

“No police officer is above the law, but we have been clear the system holding police to account is broken. I worry about the lack of support officers face for doing their best, but most of all I worry for the public. As I have said before, the more we crush the spirit of good officers, the less they can fight crime. That risks London becoming less safe. 

“If your job is confronting dangerous and sometimes murderous criminals on behalf of communities, of course timely accountability for use of force is essential. But your life being on hold for four years or more as you go through multiple accountability processes is a disgraceful way to treat brave men and women. I also see the profound effect these cases routinely have on officers’ families.

“NX121’s case is a high profile example of something that is all too common for front line officers. The consequence is that while officers’ physical bravery knows no bounds, too often they are hesitant because of the multiple legal jeopardies they face.

“Criminals are held to account once by the courts – officers can be held to account four times through criminal, misconduct, civil and inquest processes that span years. That cannot be right.”