A High Court judge on Friday cleared the way for 19 Protestant men jailed without trial in the 1970s to press ahead with legal action against British state authorities.
Proceedings were issued amid allegations the government abused its power by deciding to lock them up in a bid to balance mass Catholic internment.
Lawyers for one of the men, James Wilson, claim there was an unlawful policy which only came to light decades later.
He is suing the Northern Ireland Office, the Chief Constable, the Ministry of Defence and the Secretary of State.
Government legal representatives attempted to have the case thrown out for being brought out of time.
But Mr Justice O’Hara on Friday refused to dismiss Mr Wilson’s claims for unlawful arrest, false imprisonment and misfeasance in public office.
He said: “They may or may not succeed later when the evidence is tested and the appropriate legal test is applied to the facts which have been established, but it cannot be said at this stage that these claims will fail.”
Mr Wilson was arrested in 1973 and held for more than a year.
His barrister argued that the alleged policy remained concealed until official papers were released under the 30-year rule.
It was contended that he was interned because he was a Protestant in order to demonstrate the British state was not just detaining Catholics under that system.
Imprisonment without trial began when soldiers and RUC officers swept into Catholic areas as part of Operation Demetrius in August 1971.
More than 300 people were initially detained in what was then called the Long Kesh prison camp outside Lisburn, Co Antrim.
They were accused of involvement with the IRA.
It would take another 18 months before any loyalists were interned.
Mr Wilson is one of 19 Protestants taking legal action against the authorities. Two of the others have died since proceedings were issued.
Mr Wilson claims his arrest and subsequent internment was politically motivated after the government came under criticism for targeting only Catholics.
The court heard that at the time he was involved in political activity.
But his barrister said the government wrongly equated that with involvement in terrorism.
Mr Wilson was never prosecuted for any offence during the internment, it was stressed.
The judge was also told that a consultant psychiatrist has assessed Mr Wilson as having suffered a related injury.
Counsel for the police and Northern Ireland Office argued that the action should have been issued years earlier.
But rejecting attempts to have the action halted, Mr Justice O’Hara said: “I accept... that it is arguable that the plaintiff’s right of action was concealed by fraud on the part of the defendants, or some of them.”
Outside court Mr Wilson’s solicitor, Kevin Winters of KRW Law, said: “Today’s ruling paves the way for this important case to go to a full hearing.
“It’s not only significant for the 19 ex-internees affected but is also relevant to legacy litigation generally.
“Since the start of this case two of the men involved have died. We hope that the case will now move very quickly given the age profile of the remaining plaintiffs.”