Fatal shootings by police are rare; prosecutions of officers rarer still – and convictions are non-existent. The only two cases where on-duty police officers have stood trial in the last 20 years for murder by shooting have resulted in not guilty verdicts.
The most recent case, in 1998, was the close-range shooting of a naked, unarmed, half-asleep man, James Ashley, at a flat in St Leonards by Sussex police. The judge ruled that prosecutors could not prove that PC Chris Sherwood was not acting in self-defence during the raid.
Mr Ashley had a conviction for manslaughter but he was not armed as had been suggested during intelligence briefings. Senior officers later accepted the raid should never have gone ahead.
PC Patrick Hodgson was acquitted of murder in a 1997 after opening fire on David Ewin, who was trying to escape from officers in a stolen car. The officer said he opened fire because he believed his life and that of bystanders was at risk.
But some of the most notorious incidents of recent times have not ended up in a criminal court. Harry Stanley was killed in 1999 by police after reports that he had a gun in a bag. The gun later turned out to be a table leg, but the CPS said there was not enough evidence to suggest the two officers were not acting in self-defence.