The inquest into the Horden shootings has heard how the gunman never had his licence revoked despite threatening to kill himself.
In 2008 Durham Police took Michael Atherton's guns off him - but he was later given them back.
He would then go on to shoot himself, his partner and two members of her family on New Year's day of last year.
Watch the lunchtime update from Frances Read below.
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However, legal advice said he would win an appeal if his shotgun licence was revoked, as he had never used weapons to attack her.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."
An inquest has heard that a police firearms officer - who was convicted of selling on guns to the public - played a part in granting a gun licence to a man who shot himself and three members of his family in County Durham.
The hearing into the Horden shootings started today.
The Independent Police Complaints Commisson has already investigated why Michael Atherton was allowed several gun licences.
Today, the inquest heard there was no formal training for Durham police officers involved in granting gun licences.
Mavis, Bobby, Davey and Robert - the members of the victims' family - spoke to ITV News about the tragic day in January.
Watch the full report from Frances Read below.
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.Read the full story ›
An inquest into the Horden shootings on new years day last year has begun in County Durham.
The inquest has heard that officers at Durham Police, involved in granting the gunman a shotgun licence, did not have any formal training.
Watch the afternoon update from Frances Read below.
Michael Atherton shot his partner Susan, her sister Alison and 24-year-old niece Tanya before taking his own life at his home in Peterlee last year.
An inquest into their deaths began today and heard that a note had been attached to Atherton's request for a shotgun license in 2006 which said:
"Four domestics, last one 24/4/04, was cautioned for assault.
"Still resides with partner and son and daughter.
"Would like to refuse, have we sufficient info to refuse re public safety."
However, Atherton was still granted a shotgun certificate then and a firearms licence two years later.
The inquest also heard that there was no formal training for police officers involved in the granting of firearms licences.
Witness B, who cannot be named, said:
"There was no formal training, I'm not aware of any formal training in firearm departments.
"Ninety percent of application forms were straightforward."
Evidence was also given by pathologist Dr Nigel Cooper who said Atherton had about one and half times the alcohol driving limit in his blood at the time, which was the equivalent to a few drinks.
Atherton had previously had his guns confiscated after threatening to shoot himself when drunk.
An inquest into the deaths of a cabbie who shot himself and three members of his family has heard there was no formal training for police officers involved in granting firearms licences.
Michael Atherton shot Susan McGoldrick, her sister Alison and niece Tanya, before killing himself last year.
The inquest also heard that one investigating officer at Durham Constabulary had never seen guidance by the Home Office or the Association of Chief Police Officers on issuing gun certificates.
Atherton legally owned six weapons, including three shotguns, despite having a history of domestic abuse.
Officers from Durham Police who gave evidence at Coroner's Office, Crook, County Durham, said there was no formal policy written down regarding firearms for them to use.
This led coroner Andrew Tweddle to describe the force's procedures as "more of an ad hoc arrangement".
An inquest into the death of a taxi driver who shot three members of the same family before turning the gun on himself is taking place.
Michael Atherton, killed his partner Susan McGoldrick, her sister Alison and niece Tanya, before taking his own life on New Year's Day 2012 at his home in Horden.
Atherton legally owned firearms despite a history of domestic violence.
He had his guns removed by police after he threatened to blow his own head off when drunk, but they were returned weeks later.
Alison Turnbull's son Bobby wants to tighten gun ownership legislation to stop further tragedies.
He has already won the backing of shadow home secretary Yvette Cooper after meeting her earlier this year.
Bobby is calling for changes to gun laws, including stricter checks of medical records, and hopes the coroner will make recommendations to the Home Secretary at the end of the hearing.
"There's a lot of little questions I have that I want answering.
"I hope they will come out through the course of the inquest, which might put my mind at rest and help me to understand."
An inquest into the deaths of the Horden shootings in County Durham is starting today.Read the full story ›
An inquest into the Horden shootings in County Durham is due to start today. On New Year's day last year Michael Atherton shot dead his partner as well as two other members of her family - before killing himself. The inquest will look into the circumstances surrounding the deaths.