Making the provision of state funding to schools conditional on ending any religious discrimination would be a way of dealing with the 'baptism barrier', according to new legal advice.
Equate, a group campaigning for an end to the 'baptism rule' in Catholic schools, said the opinion from three constitutional experts cleared the way for a change in legislation if the political will is there.
The advice was drafted by Dr Conor O'Mahony of University College Cork, Dr Eoin Daly of NUI Galway and Dr David Kenny of Trinity College, Dublin.
The law allows religious-run schools to protect their ethos by giving priority enrolment to children who have been baptised - and this is deemed to have constitutional protection.
It is a major source of contention because the Catholic Church controls 90pc of schools and local children who have not been baptised may not get a place.
But the new advice states: "There is no constitutional right to unconditional public funding for private or denominational schools and the Constitution permits the imposition of reasonable conditions on the provision of public funding."
A spokesperson for Education Minister Richard Bruton said the primary way the minister was seeking to deliver greater diversity was by opening more multi- or non-denominational schools.
He noted that the previous Oireachtas education committee found that the Constitution "poses a particular difficulty when legislating in this area."
The spokesman added that the minister was keen to discuss this "very complex issue" with the committee and would also be meeting with Equate in the coming weeks.