The mother of Mark Duggan, whose death sparked nationwide riots after he was fatally shot by police, is challenging an inquest verdict of "lawful killing".
Family members and supporters reacted with shock and anger after the inquest jury returned their verdict at the Royal Courts of Justice in January on 29-year-old Mr Duggan.
Lawyers for Pamela Duggan will argue today at London's High Court that the jury was misdirected and the verdict should be overturned.
They say the presiding coroner should have told the jury that, if they were sure Mr Duggan was not holding a gun, then they could not return a lawful killing verdict.
They also contend that the jury was wrongly directed on the question of "mistaken belief" involving the police marksman who shot Mr Duggan.
Carole Duggan, Mark's aunt said: "We as a family, like a lot of the public, were shocked by the outcome of the inquest into Mark's death - that the jury could have reached a lawful killing conclusion when they also concluded Mark was unarmed.
"We are equally shocked by the coroner's report, as his concerns, based on his recommendations, mirror exactly the concerns of the family before the inquest had even begun.
"As a result we are further confused by the contradictions in between the jury's findings and the detailed coroners report."
The inquest jury found Mr Duggan was lawfully killed by a police marksman in August 2011 in Tottenham, north London, despite being unarmed when he was shot.
Police officers intercepted the vehicle he was in on the basis of intelligence that he was part of a gang and had collected a gun.