Last Thursday morning, heavy stationery boxes from Áras an Uachtaráin were hand-delivered to about 25 addresses around Ireland.

Each box contained an official notice of the news each of the recipients had received by phone late the previous night: President Michael D Higgins was convening the Council of State for the first time since he had taken office in 2011.

The box held a stack of documents that together amount to a primer on one of the most controversial, drawn-out political and legal sagas in decades. As well as copies of the Protection of Life During Pregnancy Bill, there was an explanatory memo, extracts from Dáil and Seanad debates, representations made to the President and press cuttings on the abortion debate. Also in the box were copies of the 1992 judgments of the High Court and Supreme Court in Attorney General v X, the decision of the European Court of Human Rights in the A, B and C v Ireland case, and the relevant articles of Bunreacht na hÉireann.

Set-piece
This afternoon, just four days on, members of the council will meet in the main dining room at the Áras for one of the more unusual set-piece events in Irish national life. Around the table will be the President, the most senior members of the executive and judiciary, former presidents, taoisigh and chief justices as well as seven of the President's own nominees. The council's brief is to discuss whether Mr Higgins should sign the abortion Bill or use one of the few discretionary powers he holds by referring it to the Supreme Court to test its constitutionality.

Presidents have tended to use the council sparingly – Mr Higgins’s predecessor, Mary McAleese, convened it eight times in 14 years – but the body has developed a set of codes and procedures that have held constant for decades. “They’re quite formal occasions, and they’re a big political occasion for everybody involved because of the very unusual nature of the collection of people who are brought together,” says one former member. “Those people would never meet around a table at any other moment.”

Key groups
Up to 26 people are expected at today's meeting, but according to a number of people with knowledge of the process, there will be three key groups. The critical role is that of Attorney General Máire Whelan, who will know the Bill more intimately than anyone else in the room and has a lot riding on the outcome. She will be heavily involved in presenting the legislation and responding to queries. "The star person in the proceedings is the Attorney General," says one former member. "This is the Attorney General's moment." Tánaiste Eamon Gilmore, who knows the President as well as anyone around the table, will be an influential voice.

The second key group is the judiciary. Seven current or former Supreme Court judges have seats on the council, including two members of the current court: Susan Denham and John Murray. While sitting Supreme Court judges do get involved in the discussion, former members say there is a convention whereby sitting judges are careful not to take substantive positions unless they think the issue is clear-cut. The input of figures such as Nicholas Kearns, the president of the High Court; ex-Supreme Court judge Catherine McGuinness and former chief justices Ronan Keane and Tom Finlay – if they attend – will therefore be even more important.

The third key group is made up of former presidents Mary Robinson and Mary McAleese, who know the process well and happen to be both ex-politicians and constitutional lawyers as well.

Politics with a small 'p'
But, while the discussion is ostensibly about the law, politics inevitably crops up. "It's politics with a small 'p' – the impact on society – but not party politics," says one well-placed source. "Everything is political," says another.

A lot hinges on the position taken by the three Government members. Will they argue that it would be preferable to make the Bill immune from future challenge, as would happen if the Supreme Court found it constitutional? Or will they press for the President’s signature, seeking to avoid a referral process that tends – given that the court is asked to decide on an abstract question rather than on concrete facts – to be far more unpredictable?

Ultimately, however, it will be the President’s call. He is required to convene the council before a referral, but he enjoys a constitutional prerogative to ignore its advice completely. “This is quite a key moment,” says a source, “and at the end of the day, despite all the wisdom around the room, there’s only one voice that matters in the end.”