The High Court has dismissed an action aimed at blocking the PSNI's Deputy Chief Constable Drew Harris from becoming the next Garda Commissioner.

Ciaran MacAirt, whose grandmother Kathleen Irvine was one of 15 people killed at McGurk's Bar in Belfast in December 1971, had asked the High Court to judicially review the Government's decision to appoint Mr Harris.

In his judgment, Mr Justice Denis McDonald said Mr MacAirt had not reached the legal threshold required that would allow the challenge to go before a full hearing of the High Court.

While Mr MacAirt has the right to appeal the ruling to the Court of Appeal, the decision clears the way for Mr Harris to take up his role as Garda Commissioner.

The State had opposed the application and argued Mr MacAirt's action was "unstateable", "novel" and should be dismissed.

In proceedings against the Minister for Justice, Ireland and the Attorney General, Mr McAirt had sought various orders, including one quashing the decision to appoint Mr Harris as commissioner.

He also sought various declarations, including that the State is obliged to conduct independent investigations into murders of Irish citizens where there is credible evidence of collusion.

He further sought a declaration that due to his obligations under the UK's Official Secrets Act and his role in the protection of the PSNI, the RUC and other agencies of the UK, Mr Harris would be incapable of controlling an independent investigation into the murder of Irish citizens where collusion between loyalist terror gangs and British security forces was alleged.

The State, represented by Remy Farrell SC, argued Mr MacAirt’s case was "unstateable" and even when taken at its height was "nothing more than an expression of an opinion" that the applicant does not agree with Mr Harris's appointment.

Barrister Gerard Humphreys, instructed by McGeehin Toale Solicitors for Mr MacAirt, argued Mr Harris lacked the independence required to be Garda Commissioner due to this role in the PSNI and its predecessor the RUC.

He argued Hr Harris could not direct or control any garda investigation into the murder of an Irish citizen where there is credible evidence of collusion between the killers by the RUC or agencies of the British state, including the Dublin Monaghan bombings.

Due to his senior role with the PSNI, and contacts with other agencies of the British state including MI5, Mr Harris has possession of information directly relevant to garda investigations into the murder of Irish citizens during the Troubles.

Mr MacAirt said he was shocked by the decision to appoint Mr Harris.

Ciaran MacAirt said there has never been a proper investigation into the bombing

He said he has written a book about and researched the McGurk's Bar bombing and is a director of the Charity Paper Trail, which supports victims and survivors of the Troubles.

He claimed he has been trying to establish the truth behind the bombing.

The RUC initially blamed it on an IRA bomb being accidentally detonated when in fact the bomb was deliberately planted in the bar by the UVF.

Mr MacAirt claims there was never a proper investigation into the bombing, and claims there was RUC cover-up in regards to what happened.

He claimed his efforts to find the truth have been frustrated by the PSNI, and have been consistently obstructed by Deputy Chief Constable Harris.