The British Supreme Court has ruled a PSNI decision to discontinue its investigation into the torture of the 'Hooded Men' in 2014 was unlawful.
Seven judges ruled the decision was wrong and that the treatment the men were subjected to would be characterised today as torture.
It follows a hearing before the court in June - which heard arguments the 12 men were subjected to torture after being held without trial.
The men claim they were tortured in August 1971, following a major arrest operation in Northern Ireland.
This was carried out using powers of detention referred to as 'internment.'
The men were detained in the custody of the Royal Ulster Constabulary (RUC) with support provided by military personnel.
During their detention, Sean McKenna was subjected to treatment which was later found by the European Court of Human Right to have been in breach of Article 3 of the European Convention on Human Rights.
'Fifty years is a long time'
Amnesty International has described the ruling as a 'victory for justice'.
The human rights group investigated the torture in the 1970s and says it "always supported the calls for an independent investigation".
On the outcome Francis McGuigan, one of the 'Hooded Men', says: "I am relieved with the outcome today.
"Fifty years is a long time to wait for justice - that changes today - the investigation into torture must now immediately get underway.
"The investigation previously started with Jon Boutcher before the PSNI's decision to stop it. It must begin again with urgency.
"The UK government proposal to end investigations must not become law and interfere with long overdue truth and accountability in my or any other case.
"My message to other victims is take hope from today and keep fighting", he adds.
'No legislating for impunity'
Grainne Teggart, Amnesty International's campaigns manager, says: "Today's decision is a victory for justice.
"The message is clear, the PSNI acted unlawfully by refusing to proceed with an investigation into state-sanctioned torture.
"In doing so it shamefully added to the trauma already inflicted and has delayed the truth, justice, and accountability to which these men are entitled.
"The ruling today comes at a critical time when the stakes for victims' rights could not be higher."
She adds: "The UK government plans to end investigations and close down all paths to justice for victims of The Troubles. This cannot happen.
"There must be no legislating for impunity. Perpetrators of human rights abuses must not be shielded at the expense of victims".
She says this ruling should stop the British government "in its tracks".
"Justice delayed is still better than justice denied and it's completely wrong for people in authority to try and put themselves above the law," she adds.