The European Court of Human Rights has rejected a request by the Republic to find that internees detained by the British government during the Troubles in the so-called Hooded Men case suffered torture.
Dismissing the request by six votes to one, the ECHR said there was "no justification" to revise a 1978 ruling which found the treatment of the men was inhumane and degrading.
Amnesty’s Northern Ireland campaigns manager Grainne Teggart speaks following today's ruling
The court said new evidence had not demonstrated the existence of facts that were not known to the court at the time or which could have had a decisive influence on the original judgment.
The Dublin government took legal action after the new evidence emerged and amid pressure from Amnesty International and other human rights organisations over the so-called Hooded Men case.
They were 14 Catholics interned - detained indefinitely without trial - in 1971 who said they were subjected to a number of torture methods.
These included five techniques - hooding, stress positions, white noise, sleep deprivation and deprivation of food and water - along with beatings and death threats.
The men were hooded and flown by helicopter to a secret location, later revealed as a British Army camp at Ballykelly, outside Derry.
They were also dangled out of the helicopter and told they were high in the air, although they were close to the ground.
None were ever convicted of wrongdoing.
A statement from the court said: "The European Court of Human Rights has rejected a request by Ireland to revise a 1978 judgment and find that men detained by the United Kingdom during Northern Ireland's civil strife suffered torture, not just inhuman and degrading treatment."
It added: "The court found that the Government of Ireland had not demonstrated the existence of facts that were unknown to the court at the time or which would have had a decisive influence on the original judgment. There was therefore no justification to revise the judgment."
The revision request was dismissed by six votes to one. The judge elected by Ireland issued a dissenting opinion.
Read more:Key questions after European Court refuses to revise 'Hooded Men' torture ruling
The Dublin government first took a human rights case against Britain over the alleged torture in 1971.
The European Commission ruled that the mistreatment of the men was torture, but in 1978 the European Court of Human Rights held that the men suffered inhumane and degrading treatment that was not torture.
The British government did not dispute the finding.
New evidence, uncovered from national archives in London, throws doubt over the ruling by the European Court of Human Rights.
It included a letter dated 1977 from then-home secretary Merlyn Rees to then-prime minister James Callaghan in which he stated his view that the decision to use "methods of torture in Northern Ireland in 1971/72 was taken by ministers - in particular Lord Carrington, then secretary of state for defence".
Mr Rees added that "a political decision was taken".
However, in its latest ruling the ECHR found that the documents did not demonstrate facts which were unknown at the time.
And, even if it could be shown that misleading evidence had been provided about long-term psychiatric effects on the men, the court said it could determine whether such knowledge might have had a decisive influence leading to a finding of torture.
The ruling said: "The original judgment had made no reference to the issue of such long-term effects and it was difficult to argue that the court had attached particular significance to that aspect of the case."
The original judgment had stated that the difference between "torture" and "inhumane and degrading" treatment depended on the intensity of suffering, which in turn depended on a number of elements.
It was not clear that the one element of long-term psychiatric suffering would have "swayed the court into a finding of torture".
The judge elected in respect of Ireland issued a dissenting opinion.
Amnesty International said it was disappointed at the ruling.
Amnesty’s Northern Ireland campaigns manager Grainne Teggart said when the organisation visited the detainees in 1971 "we found clear evidence of torture. Our findings have not changed in the years that have passed".
“The hooded men’ have been denied justice for too long. The UK government must now urgently conduct an independent and effective investigation into what happened, and prosecute any state agents involved in sanctioning or carrying out these violations at the time," she added.
