The government will revive a review into how police officers who take fatal shots in the line of duty are held to account following the shooting of Chris Kaba, the prime minister said.
The probe was initially launched by the previous government, but will now be completed by Home Secretary Yvette Cooper.
Sir Keir Starmer said it was important that the public have confidence in the police and that police have confidence in the government.
It comes days after police officer Martyn Blake was cleared of the murder of Mr Kaba.
"We are going to pick [the probe] up and complete that accountability review because it is important that the public have confidence in the police including of course the armed police,” Sir Keir said.
“It's also important that the police know that we have confidence in them doing a very difficult job, so we will pick that up.”
He added that more details would be available later on Wednesday when Ms Cooper makes a statement in the House of Commons.
Under the current law, every armed police officer is personally responsible for their actions. Officers cannot use more force than is necessary to neutralise a threat.
A superior officer cannot tell a police officer to pull the trigger - nor can there be a pre-emptive tactical decision to shoot a suspect whatever the circumstances.
On Monday, police officer Mr Blake was cleared of murdering Chris Kaba, who he shot in the head during a police vehicle stop in south London two years ago.
It has since been revealed that Mr Kaba had shot a man in a nightclub days before his own death.
Reacting to the verdict Metropolitan Police Commissioner Sir Mark Rowley said no police officer was above the law but said the force had 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," he said.
"The more we crush the spirit of good officers, the less they can fight crime - that risks London becoming less safe."
Abimbola Johnson, a barrister on a scrutiny board set up by the National Police Chiefs Council in the summer to boost confidence among minority ethnic people, warned against using the Kaba case to push for legislative change.
"It is already extremely rare for us to see police officers being prosecuted under the criminal justice system for action they have conducted whilst in the line of duty," she told BBC Radio 4's Today programme.
She added: "This is not a typical case, therefore, using this as a reason to push for legislative change, it doesn't make sense, because this isn't normally what would happen throughout the process."