The decision on Friday follows an earlier high court ruling which prevented his mother 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 (Acpo).
At the high court in June, Duggan argued that the policy did not include appropriate measures to reduce the risk of officers involved in a fatal shooting conferring with each other before producing accounts.
But at that stage, Lord Justice Laws and Mr Justice Wilkie, presiding, blocked her legal attempt to seek a review, ruling that she did not have an arguable case.
After the appeal, judges gave permission for the case to continue, Marcia Willis Stewart, of law firm representing the Duggan family, said: “This is a case where the use of conferring is of great importance.”
For full story go to http://www.theguardian.com/uk-news/2014/mar/07/mark-duggan-family-challenge-police-practice-officers-conferring-appeal