Saskia Jones' family are suing the Government for alleged failings that led to her murder last year.
Ms Jones, 23, was fatally stabbed along with Jack Merritt, 25, by convicted terrorist Usman Khan during a prisoner rehabilitation event at Fishmongers' Hall in London on November 29, 2019.
Khan, 28, attended the event, organised by Cambridge University's Learning Together programme, armed with two kitchen knives wearing a fake suicide vest and killed Mr Merritt and Ms Jones before he was shot dead by police.
Her family joins Mr Merritt's in taking legal action against the Ministry of Justice (MoJ) and the Home Office.
Saskia Jones, 23, died following a terror attack at London Bridge after convicted terrorist Usman Khan went on a knife rampage
Jack Merritt, 25, who died following the terror attack during a prisoner rehabilitation event near London Bridge on November 29 last year
Mr Merritt's parents, Anne and David, along with his brother Joe and his girlfriend Leanne O'Brien, are taking legal action against the Ministry of Justice and the Home Office at the High Court.
Terrorist Usman Khan, 28, killed Saskia Jones, 23, and Jack Merritt, 25, near London Bridge on November 29 last year
Their solicitor Kate Maynard said that Khan was a convicted terrorist under multi-agency public protection when he killed Mr Merritt and Ms Jones, which raises 'questions about the assessment and management of Usman Khan's risk'.
A writ lodged at the High Court last week under the European Convention on Human Rights by lawyers for Ms Jones' mother, Michelle, claims her daughter's life was breached by failings, according to a report in the Daily Mirror.
Henry Pitchers QC, for Ms Jones's family, pointed out during a pre-inquest hearing last month that Khan had been assessed as the 'highest level of risk' and had 22 licence conditions on his release.
Mr Pitchers told the court last month: 'We know he was a convicted terrorist, he had been out of prison for less than a year when this attack occurred.
'We know and it won't be disputed that he was subject to supervision and was also supervised by the probation services and relatively frequent contact they had with him.
A bystander of the terror attack is seen attempting to fight off Usman Khan with a narwhal tusk on London Bridge, Khan was later shot dead by police on the bridge
'As I understand it he was screened prior to release by police, released and assessed as being at the highest level of risk.
'Looking at the evidence we've seen, his last unannounced visit from police officers was... Around two weeks before the attack.
'They arrived at midday, found the flat to be dark, you see Mr Khan wasn't happy about them taking pictures of his X-box games and he asked to speak to a solicitor. He asked them to leave which they did.'