The family of a man who died after being restrained by up to 17 prison officers is suing the Scottish Prison Service, Police Scotland and the Crown Office over his death.
Allan Marshall, 30, died days after being held face down by prison officers at HMP Edinburgh in 2015.
Mr Marshall, who was being held on remand, suffered a cardiac arrest during the lengthy struggle with staff.
The officers involved were given immunity from prosecution at a fatal accident inquiry (FAI) examining his death.
The FAI found Mr Marshall’s death was “entirely preventable”, with Sheriff Gordon Liddle saying the evidence given by guards was “mutually and consistently dishonest”.
In March last year, Scotland’s Lord Advocate instructed police to examine whether the Scottish Prison Service (SPS) had corporate responsibility, but that probe remains ongoing.
Mr Marshall’s aunt, Sharon MacFadyen, has now raised a civil court claim under human rights laws for a breach of his “right to life by unlawfully causing his death”.
It is thought to be one of the first cases of its kind in Scotland.
Mr Marshall’s brother Alistair said: “We’ve been fighting for justice for Allan for nine years.
“Allan was killed in prison when he needed medical support. No one has been held responsible for that.
“The system has failed Allan. We hope that through this court case we can finally get accountability.”
Mr Marshall, from Carluke in South Lanarkshire, had been remanded to HMP Edinburgh on 2 March 2015 while awaiting trial for a breach of the peace charge.
He was said to have experienced a mental health crisis, but rather than calling for medical assistance he was moved to the segregation unit.
During this, Mr Marshall was physically restrained which led to his cardiac arrest.
Much of the incident, which at various times involved 17 prison officers, was captured on CCTV.
Mr Marshall was held face down and knelt on, with some of the officers using their feet to push him to the ground on a number of occasions.
The incident occurred on 24 March, with Mr Marshall dying in hospital on 28 March after four days in a coma.
The right to life is protected under Article 2 of the European Convention on Human Rights, incorporated into UK law through the Human Rights Act 1998.
JustRight Scotland is representing Mr Marshall’s family, claiming due to the Crown Office’s decision to grant immunity to the prison officers, this is now one of the only remaining routes to “securing accountability”.
Ms MacFadyen’s court action is also directed against Police Scotland and the Crown Office for “breach of their duty to adequately investigate Mr Marshall’s death and hold those responsible to account”, which is also a requirement under Article 2.
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Barbara Bolton, legal director and partner at JustRight Scotland, said: “This case highlights the urgent need for transparency in deaths that occur in state custody.
“Research shows a troubling rise in these deaths, reflecting preventable issues within the prison system.
“Human rights law, particularly Article 2 of the European Convention on Human Rights, mandates that the state protects the right to life.
“Thorough investigation and holding those responsible to account are essential for delivering justice to families and addressing critical issues within the prison system.”
The defenders in the case will be Scottish ministers, on behalf of the SPS; Lord Advocate Dorothy Bain KC, on behalf of the Crown Office and Procurator Fiscal Service (COPFS); and Chief Constable Jo Farrell, on behalf of Police Scotland.
The SPS, COPFS and Police Scotland are aware of the civil action but each said it would be inappropriate to comment further given the live proceedings.
In regards to Mr Marshall’s case, a COPFS spokesperson said: “The Lord Advocate instructed that Police Scotland investigate possible corporate responsibility by the Scottish Prison Service.
“COPFS is working closely with the police on this ongoing investigation and the family will continue to be kept updated on significant developments.”
Police Scotland confirmed the investigation remains ongoing.
A spokesperson for the SPS said: “Our thoughts remain with Mr Marshall’s family.”