The widow of Official IRA man Joe McCann is set to sue the PSNI amid claims police failed to properly investigate his killing.
Mr McCann was shot dead by British soldiers in the Markets area of Belfast in April 1972.
The family of the 24-year-old believe he was shot in the back as he ran from British soldiers and an RUC officer close to the city centre.
Two former paratroopers, known as Soldier A and C, had denied allegations of murder.
They were formally acquitted when their trial collapsed in May after evidence presented by the Public Prosecution Service (PPS) was considered inadmissible.
Mr McCann's widow Anne has now launched legal proceeding against the PSNI on several grounds including misfeasance in public office, negligence and conspiracy to commit an unlawful act.
Notice has been served in the case and lawyers for the family argue that British soldiers were not "subject to effective criminal justice investigations" in relation to the killing.
They also cite the "failure to ever investigate his death effectively".
Soldiers A and C were interviewed by the Historical Enquiries Team (HET), in 2010 and it was that evidence which formed a substantial part of the prosecution's case.
A judge later ruled that evidence as inadmissible.
Both men had given statements to the Royal Military Police in 1972 and were interviewed by the Historical Enquiries Team in 2010.
Neither has ever been arrested or questioned about Mr McCann's death by the PSNI.
His son, Feargal McCann, said his family was left with no other option.
"We will continue to use any and all mechanisms available to address the systematic failures in the investigative process which have led us to this point," he said.
Solicitor Kevin Winters, of KRW Law, said "the failings in the prosecution of soldiers A and C occurred on the PSNI's watch.
"This case is about accountability for the HET failings," he said.
"This is especially so on the key issue relating to the approach to interview of ex-military veterans.
"This challenge is timely given the latest pronouncement by the British government on amnesties for veterans.
"It's a reminder that families won't hesitate to use the courts to contest the continued politicising of the past."
Micheál Smith from the Pat Finucane Centre said: "We absolutely, 100 percent, support the McCann family and other families who found themselves in the same situation in their ongoing and determined fight for justice."
A spokesman for the PSNI said: "As we understand legal proceedings are pending, it would be in appropriate to comment."
