An inquest has heard how a history of domestic violence did not automatically mean police could revoke the gun licence from a man who went on to shoot three people dead then kill himself.
Michael Atherton shot his partner Susan, her sister Alison, and her niece Tanya before killing himself last year.
Retired chief superintendent Carole Thompson-Young, who headed Durham Police's firearms licensing unit, said he was known to have a history of violence towards Susan.
However, legal advice said he would win an appeal if his shotgun licence was revoked, as he had never used weapons to attack her.
In a similar case, involving a different force, a gun owner had won an appeal against having his licence revoked.
She took that legal advice to mean that Atherton's history of domestic violence was not an "automatic barrier" to having a shotgun licence.
"The judge deemed that the person was entitled to have a gun because there had been no guns used in relation to the domestic violence."
"The force appealed against the outcome but the original appeal stood."
The coroner has ruled that the deaths of three members of the same family, and their shooter, could have been avoided.
An inquest has heard how a man who went on to kill three members of his family before turning the gun on himself had been warned by police.
The inquest into the deaths of a man who shot himself and three members of his family on New Years Day 2012 has been taking place today.