Relatives of a man shot dead by police eight years ago are to ask the Royal Court of Justice for permission to sue the force's former chief constable.
James Ashley was in bed when officers opened fire in 1998
James Ashley, 39, of Liverpool, was unarmed and naked when he was shot during a drugs raid at his flat in St Leonards, Hastings, in 1998.
Sussex Police admitted negligence at the time of the shooting.
Mr Ashley's family now want to sue Paul Whitehouse for misfeasance - carrying out a legal act illegally.
Three senior police officers were cleared in 2001 of any wrongdoing in the raid but the circumstances surrounding the shooting led to the resignation of Paul Whitehouse.
Mr Ashley's sister, Pauline, said he was ultimately responsible.
"We hope to achieve some sort of justice for the death of my brother," she said.
"The buck stops with the chief constable of a police force, so he has to be answerable to what his officers have been doing."
In 2005, a High Court judge ruled that Mr Ashley's family would not be allowed to sue the police force.
The family wanted to pursue claims for alleged abuse of power last March.
But Mrs Justice Dobbs ruled the family should not have access to confidential reports on the shooting.
Police marksman Chris Sherwood, who was said to have fired the fatal shot, was cleared of unlawful killing after he said he had fired in self defence.
Liverpool Riverside MP Louise Ellman said there is "no doubt that a grave injustice was done to James Ashley".
"I can fully understand how the Ashley family feel," she added.
"He should not have died, and there was a deliberate attempt to cover up what had happened.
"Paul Whitehouse has never been brought to account."