The police watchdog says it is trying to contact key witnesses to the shooting of Mark Duggan, who have so far refused to be interviewed
Met Police chief thanks Duggan family after they appeal for peace as friend says family are 'still too raw' to meet with police watchdog.
Jurors decided that he did have a gun but it was not in his hand when he was shot.
Family members and supporters of Mark Duggan reacted angrily after an inquest in January found that police lawfully killed the 29-year-old.
The inquest jury found that Duggan was lawfully killed by a police marksman in 2011 when officers stopped the vehicle he was travelling in.
His death sparked protests in London that exploded into riots and looting across the country.
A judge has since ruled that Pamela Duggan has an "arguable case" to challenge the verdict onto the killing.
The mother of Mark Duggan, who was fatally shot by police in 2011, has been given permission to challenge the inquest verdict that he was lawfully killed.
A judge ruled that Pamela Duggan can apply for a review after her lawyers claimed the coroner's direction to the jury was "arguably inadequate".
An inquest jury had previously concluded that Mark Duggan was lawfully killed by a police marksman in August 2011 in Tottenham, north London.
Mrs Duggan's lawyers will contend that the coroner did not address questions which, if they had been addressed, meant the lawful killing verdict could not stand at a hearing to take place at a later date.
The judge said the case should go before a panel of judges including either the Lord Chief Justice, Lord Thomas, or the President of the Queen's Bench Division, Sir Brian Leveson.
Leading judges have given the go-ahead for a legal challenge over police practices linked to the shooting of a man in Tottenham whose death sparked nationwide riots.
The decision by three Court of Appeal judges in London today follows an earlier High Court ruling which prevented the mother of Mark Duggan from seeking judicial review of guidance intended to stop police officers conferring before giving statements.
Lord Justice Maurice Kay, Lord Justice Aikens and Lord Justice Lewison, ruled that there was an "arguable" case, paving the way for a full hearing at a date to be fixed.
The action brought by Pamela Duggan, whose 29-year-old son died after being shot in Tottenham, north London, in August 2011, relates to a policy adopted by the Association of Chief Police Officers.
At the High Court last June she argued that the Acpo policy did not include "appropriate measures" to reduce the risk that officers directly involved in a fatal shooting conferred with each other before producing accounts.
But at that stage Lord Justice Laws and Mr Justice Wilkie blocked her bid to seek a review, ruling that she did not have an "arguable" case.
Family members and supporters reacted with shock and anger after an inquest jury concluded at the Royal Courts of Justice that police acted lawfully when they shot Mr Duggan.
The inquest jury found Mr Duggan was lawfully killed by a police marksman despite being unarmed when he was shot.
His aunt, Carole Duggan, has said the family would fight the verdict itself through the courts.
In a statement the Metropolitan Police service said specialist firearms officers are called to more than 11,000 incidents a year, of which 3,000 are firearms incidents.
It said that 1,200 pre-planned firearms operations are run across the force, and yet officers only fire shots once or twice a year.
Armed criminals have killed more than 50 people in London in the past three-and-a-half years, the Met said, while of the eight people killed in pre-planned operations in the last decade, only two have followed the "hard stop" tactic.
– Metropolitan Police statement
The alternative to using this tactic is to allow highly dangerous criminals who get into cars with guns intent on committing harm to carry out the crime, only investigating it afterwards, with potentially catastrophic consequences.
It was wrong not to formally review the tactic in 2005 following the IPCC recommendation. This is a national tactic to which we subscribe. However, following the result of the Azelle Rodney enquiry, an interim review has been completed by the College of Policing and the MPS will now work to see if there are any alternative or better tactics available.
The Metropolitan Police has admitted it was wrong not to review its use of the "hard stop" tactic employed in the shooting of Mark Duggan in 2011, despite being advised to do so by the complaints watchdog.
The Independent Police Complaints Commission recommended the review in 2005 following the shooting of suspected drug dealer Azelle Rodney, saying it was a "high risk option" which carried risks to the public, suspects and officers.
Police officers could be banned from conferring in the aftermath of fatal shootings like that of Mark Duggan.
The Independent Police Complaints Commission says it plans to issue new guidance advising that officers should be separated before they give statements about what happened.
Conferring among officers has been a controversial issue in a number of cases, including the death of Brazilian electrician Jean Charles de Menezes.
– IPCC spokeswoman
"It's our view that officers should be separated in death cases before they give their accounts."
The Prime Minister told David Lammy: "I am always prepared to look at reforms of organisations like this. There was a big reform some years ago to make the IPCC much more independent. You are shaking your head saying it isn't working, I'm very happy to look at arguments."
David Cameron says he is prepared to look at reforms of the police complaints system after errors were found in the case of Mark Duggan.
The Prime Minister was urged to look into the current system by Tottenham MP David Lammy at Prime Minister's Questions.
Following the jury's finding of lawful killing in the Mark Duggan inquest, the Metropolitan Police Service will now start the post- incident support programme for the firearms officers involved.
– Metropolitan Police
This process includes medical tests, refresher training and an assessment of the individual officer's welfare. It is only after this process has been completed, which can take a number of weeks, that officers are eligible to return to carrying a firearm or commanding an armed operation if they choose to do so.
Any suggestion the officers will immediately be deployed with firearms is premature. This process applies equally to those officers who carry a firearm or who are deployed to command armed operations.