The UK's highest court has said Gerry Adams was imprisoned illegally by the British government when he was interned without trial in the early 1970s.
The Supreme Court has quashed his two convictions for trying to escape from Long Kesh Prison.
Lawyers for the former Sinn Féin President had argued that those convictions were unlawful as his detention was unlawful.
They said his detention order was flawed because it had not been "personally considered" by the Secretary of State for Northern Ireland in accordance regulations at the time.
In a judgment this morning, five judges, led by the former Lord Chief Justice of Northern Ireland Brian Kerr, agreed.
In their ruling, they said Mr Adams' detention should have been authorised by the Secretary of State personally and because it was not the order to detain him was invalid.
They said his detention was unlawful and as a result his imprisonments for attempting to escape were also unlawful.
Delivering the judgment this morning, Lord Kerr said the five Supreme Court judges unanimously allowed Mr Adams' appeal against his convictions.
"Mr Adams detention had not been lawfully authorised", he said.
"His detention was therefore invalid and it follows that he should not have been convicted of attempting to escape lawful custody."
Mr Adams has welcomed the judgment and called on the British government to identify and inform other people whose internment may also have been unlawful.
In a statement, he thanked his legal team and the Pat Finucane Centre which he said had in 2009 uncovered communications from July 1974.
The UK's highest court has said Gerry Adams was imprisoned illegally by the British government when he was interned without trial in the early 1970s. Mr Adams welcomed the judgment and said it will impact many of those who were interned. | Read more: https://t.co/et1TvW8YxE pic.twitter.com/nW3yWOROgm— RTÉ News (@rtenews) May 13, 2020
"Of course internment, later described as detention by the British, was never lawful. In fact it set aside the normal principles of law and was based on a blunt and brutal piece of coercive legislation
"I have no regrets about my imprisonment except for the time I was separated from my family.
"However, we were not on our own. It is believed that around two thousand men and women were interned during its four and a half years of operation.
"I consider my time in the Prison Ship Maidstone, in Belfast prison and in Long Kesh to have been in the company of many remarkable, resilient and inspiring people.
"Internment like all coercive measures failed.
"There is an onus on the British government to identify and inform other internees whose Internment may also have been unlawful", he said.
Gerry Adams said he has no interest in an apology from the British government after the UK's highest court said he was illegally imprisoned in the early 1970s. He instead called for 'a date for the referendum’ in Northern Ireland. | Read more: https://t.co/et1TvW8YxE pic.twitter.com/1w3GpUKySR— RTÉ News (@rtenews) May 13, 2020