The Supreme Court has reserved its decision in an action by two men charged with a murder at the Regency Hotel in Dublin in 2016, aimed at stopping them being tried before the non-jury Special Criminal Court.

Gerry Hutch, 59, and former Dublin City councillor Jonathan Dowdall, 44, and from the Navan Road in Dublin are charged with murdering 33-year-old David Byrne at the hotel on 5 February 2016.

Both men sought declarations from the High Court that their trials before the Special Criminal Court would be unlawful and in breach of their fundamental rights.

They argue that the Special Criminal Court is operating as a permanent court when it was set up on a temporary basis 50 years ago.

Their challenge was dismissed by the High Court and the Supreme Court agreed to hear their appeal as it raised issues of exceptional public importance.

Senior Counsel Michael O'Higgins on behalf of Mr Dowdall argued that the issue before the judges was whether or not the Special Criminal Court was operating as a temporary or a permanent court.

He argued that if it was operating as a permanent court, that was not allowed under the legislation.

He said the Supreme Court would have to decide if there was a legal duty to keep the need for the SCC under review and if that duty had been discharged.

Mr O'Higgins said the SCC had "morphed" into a permanent court and he said this breached the legislation setting it up.

Senior Counsel for Mr Hutch, Brendan Grehan, said they were calling on the Supreme Court to interpret what the relevant section of the Offences Against the State Act meant.

He said if the State was correct, the legislation allowed the Government to issue a proclamation allowing the Special Criminal Court to come into effect whenever it wanted to, without any oversight by the courts.

Mr Grehan said this was not an acceptable state of affairs.

He said the Government's interpretation gave it virtually unreviewable and irrevocable power, in perpetuity, with no oversight.

The State opposed the men's appeal.

Senior Counsel Remy Farrell for the Director of Public Prosecutions and Minister for Justice said the question of whether or not there should be a review of the Special Criminal Court and how often it should happen was a purely political decision.

The DPP argues that the words in the legislation do not impose any temporary limitation on the operation of the Special Criminal Court.

The court also heard that the legislation gives the power to pass a resolution to annul the proclamation allowing the SCC to come into force, if necessary but there had been no such attempt to annul it.