The British Government is facing mass legal action over alleged collusion with loyalists in murders in the 1970s.
A total of 32 families are to claim the police, Army and Northern Ireland Office facilitated or sanctioned the co-operation, their solicitor said.
High Court writs have been served in relation to a test civil case involving three deaths.
Lawyer Kevin Winters said: "The failure of the PSNI to sanction an overarching, thematic Historical Enquiries Team (HET) report linking all of the atrocities together and the recent collapse of the Haass proposals on the past has left many families with little alternative but to take legal action to get justice and closure."
The court action focuses on killings linked to a loyalist group in Mid Ulster known as the Glenanne gang, who legal representatives of the family claimed were linked directly and indirectly with the security forces.
They were associated with the killing of up to 120 people in a murder spree spanning a five-year period in the late 1970s.
Among their victims was nationalist SDLP branch secretary Denis Mullen, who died on September 1, 1975.
The weapon used to gun him down at the front door of his family home in Collegeland, Co Armagh, had been stolen from Glenanne UDR base four years earlier, Foyle MP Mark Durkan has told the House of Commons.
Late last year, Mr Durkan told MPs Mr Mullen was shot 27 times.
A test civil case is being taken by Denise Fox, Mr Mullen's daughter.
Writs have also been served relating to the killings of Patrick Falls, a Catholic murdered during a 1974 attack on a bar in Clonoe in Co Tyrone, and the death of Betty McDonald at a bar in Keady, Co Armagh.
Mr Winters said the first preliminary hearing of an inquest into Ms McDonald's death would be held after Easter when his firm would ask the coroner to consider all Glenanne cases on a linked basis.
He added: "We are supported in this approach by the Police Ombudsman."
A PSNI spokesman said: "It would be inappropriate to comment, as legal proceedings have started."