Former Sinn Féin president Gerry Adams has failed in his bid to overturn his 1975 criminal convictions for attempting prison escape.

Mr Adams was one of nearly 2,000 people who were interned without trial in the early 1970s.

He twice attempted to escape from Maze Prison and was subsequently convicted in two separate Diplock Court trials.

Lawyers for Mr Adams argued before the Court of Appeal in Belfast that the interim custody order (ICO) ordering his detention in 1973 was invalid as it had not been considered by a Secretary of State.

However, the court was satisfied that the ICO, signed by a minister of state on the Secretary of State’s behalf, was valid.

Part of the case focussed on the wording of article 4(1) of the Detention of Terrorists (NI) Order 1972, which states that “where it appears to the Secretary of State” that the conditions for the making of an ICO exist, “the Secretary of State may make an order”.

However, the Court of Appeal said the wording is “a common legislative formula” and had “not been found in previous cases to be the basis for any necessary implication of personal consideration”.

The Court also referred to the case law developing the Carltona principle, which states that the duties imposed on ministers are so multifarious that no minister could ever personally attend to them and that the duties are normally exercised under the authority of the ministers by responsible officials of the minister’s department.

The Court concluded that the starting point, if not the presumption, is that the Carltona principle applies and can only be displaced by Parliament using express words or by necessary implication.