Legal proceedings are due to get under way in Dublin's High Court in a challenge against the choice for the country's new police chief.
Ciaran MacAirt, whose grandmother Kathleen Irvine was killed during The Troubles, has brought the action in a bid to prevent PSNI Deputy Chief Constable Drew Harris from being appointed to the role.
Mrs Irvine was one of 15 people killed by loyalists in the bombing of McGurk's Bar in Belfast in 1971.
Mr MacAirt, who is being represented by Kinnear and Co solicitors with the assistance of MacGeehin Toale Solicitors in Dublin, is applying for leave for a judicial review of Mr Harris's appointment.
The PSNI deputy became the first Garda chief appointed from outside the Republic when he was announced as the new commissioner in June.
Mr Harris is a former RUC officer and his officer father Alwyn was killed by an IRA bomb in 1989.
Mr MacAirt claims Mr Harris lacks the independence required for the job due to his roles in the PSNI and the RUC.
The McGurk's bar bombing was one of the worst atrocities of the Troubles and the families of those who died have long campaigned for a fresh inquest.
The bombing was carried out by loyalists but at the time security forces blamed the IRA, prompting speculation the dead might have included IRA members who were carrying the device.
Relatives and campaigners discovered a large amount of new evidence not heard at the original inquest held the year after the bombing.
