Even before the first meeting begins, advocacy groups are complaining that they have been locked out of the hearings or given inadequate time to make submissions.
The Oireachtas Committee on Health is holding three days of intense hearings, to be broadcast live on the TV and the internet, and reporting back to the Government.
It is hoped the meetings will assist in deciding on what legislation is needed to address a European court ruling on abortion laws in Ireland.
This found Ireland needed to legislate for situations where there was a risk to the life of a pregnant woman.
But disagreement has broken out ahead of the hearings, which are being held in the Seanad due to the demand for participation among TDs as well as people outside the Oireachtas.
Ireland Stand Up, a lay Catholic advocacy group, told the Irish Examiner it had been given just hours to present a submission to the committee, and was then told there was no space for them at the hearings.
The group, which has also campaigned to reinstate the Irish embassy to the Vatican, claimed a cloak of secrecy surrounded the hearings.
Co-founder Mary Fitzgibbon said: “Most people feel the whole exercise is anti-democratic. We were never told how to apply, then one day last week were told to have a submission ready the next morning.
“We heard nothing back and when we rang the committee, they just said there were too many people [attending].”
Ms Fitzgibbon said another advocacy group representing Muslims had also been told to hand all material being presented at the hearings next week in advance to the committee.
“This all sounds like a token effort and people are aghast at the rush,” she argued.
Committee chairman Jerry Buttimer said a series of groups and individuals would appear at the Seanad hearings, which are set to last each day from 9.30am until at least 5pm.
Officials with the Irish Medical Council, masters of the maternity hospitals, psychologists, obstetricians, gynaecologists, representatives from the Law Society, constitutional experts and representatives of the Church, as well as other advocacy groups, have been invited to attend, Mr Buttimer said.
But the final list of witnesses for hearings is yet to be agreed.
He said that other groups may be asked for contributions during further hearings later in the year, once the heads of the bill on abortion were drafted.