The families of two men found hanged in their cells at Woodhill prison have brought a High Court case over the "exceptionally high" suicide rate at the jail.
Ian Brown, 44, hanged himself in his cell at the category A prison in July last year while Daniel Dunkley, 35, died a few days after he was found suspended by a ligature in his cell later the same month.
Mr Brown's mother and sister, Pearl Scarfe and Julie Barber, and Mr Dunkley's brother, Jamie Blyde, who is himself a prisoner, want the court to order Woodhill's Governor and the Secretary of State for Justice to comply with the requirements of the Prison Service Instructions (PSIs).
They cover management of prisoners at risk of harm to self, to others and from others, early days in custody and medical emergency response codes.
The Governor and the Secretary of State say the judicial review claim is "neither appropriate nor necessary".
In London on Friday, Heather Williams QC, for the families, said the claim addressed the "exceptionally high" current rate of self-inflicted deaths at the Milton Keynes prison.
There were seven self-inflicted deaths last year, five in 2015 and 18 at the prison since May 2013.
"This case concerns an exceptionally grave situation," said Ms Williams.
"The rate of self-inflicted death at HMP Woodhill is far higher than at any other prison, at a time when the suicide rate in the prison estate as a whole is at a record high.
"There is a compelling and urgent need to protect other inmates at HMP Woodhill from killing themselves."
She said the case raised serious ongoing breaches of the most fundamental provisions within Article 2 of the Human Rights Act, which protects the right to life, and involved grave, long-term failures to comply with the great responsibility placed on the authorities to protect prisoners.
"This weighs strongly in favour of the court taking a more interventionist role than it might otherwise do."
James Strachan QC said the Governor was well aware of his obligations to comply with the requirements of the PSIs and continued to take steps to ensure those obligations were met.
The Secretary of State continued to provide support to assist him in doing so.
Any self-inflicted death in custody was tragic and a matter of the utmost concern, said counsel.
"The defendants do not dispute that the number of deaths at the prison is a legitimate matter of concern. It calls for action to be taken.
"However, not only have the Governor and the Secretary of State taken significant action in 2016 to improve the situation, but as the taskforce approach shows, this is a continuing high priority.
"It is being led at a senior level in NOMS (National Offender Management Service) headquarters.
"There is a clear determination to drive through further improvements, as is evidenced by the commission of independent professional advice on the prevention of self-inflicted deaths and self-harm at HMP Woodhill."
Lord Justice Irwin and Mr Justice Garnham will give their decision at a later date.
Additional reporting by the Press Association