Azelle Rodney, 24, was shot and killed by armed officers in Hale Lane, Edgware, in April 2005 but laws governing the release of secret evidence mean a coroner is unable to hold a proper inquest.
At a hearing at Hornsey Coroner’s Court in August, coroner Andrew Walker concluded that he could not proceed at this stage because of the large quantity of what police have called “secret evidence” which is withheld for operational reasons.
The legislation means that information obtained by phone intercepts, or using other surveillance methods, does not have to be revealed.
The solicitor acting on behalf of Mr Rodney’s mother Susan Alexander has now written to the Home Office and to the Ministry of Justice to call for a change in the law.
Daniel Machover said: “The family are terribly frustrated by what has happened. It’s the waiting that has been insufferable. Azelle’s mother can’t understand why she has had to wait so long only just to get this far.”
Mr Rodney died when officers carried out a “hard stop” on the car he was travelling in after keeping him and two other men under surveillance for several hours.
The 24-year-old was sitting in the back of the car and it was claimed that he was seen holding a gun when the armed officer opened fire, although this was later disproved.
No charges were brought against police.
Contacted for comment, a spokeswoman for the Home Office said: “We accept the arguments for using this information in court but only if there are necessary safeguards to protect methods of intelligence.”