The Labour Party says the legal definition of 'family' should be changed to reflect modern Ireland.
Currently, the only legally recognised family is that created through marriage.
Any other grouping of people who are mutually supportive or dependent who may be living together - related or not - are not considered a family unit under Irish law.
Article 41 of Bunreacht na hÉireann gives special protection to the family "as the natural primary and fundamental unit group of society".
It also states that the State "pledges itself to guard with special care the institution of marriage, on which the family is founded, and to protect it against attack."
But Labour TD, and spokesperson on children, Ivana Bacik says this needs to change.
She told Newstalk Breakfast modern families need to be protected as well.
"In a sense, they've created a special bubble for families based on marriage - and excluded other households and other forms of family from Constitutional protection."
She says the practical impact of this was recently highlighted in the case of John O'Meara from Co Tipperary.
"[His] long-term partner and mother of his children, Michelle Beatty, had died tragically.
"Because they had never married, despite having co-habited for a long, long time, he could not be entitled to a Survivors Pension.
"So his relationship was not recognised by the State - whereas the State in fact does recognise co-habitation for the purpose of depriving people of benefits in other cases in our social welfare code.
"So there's inconsistency there, but there's also an unfair discrimination against co-habiting couples".
'A gap in protection'
Deputy Bacik says the current definition means there is a gap in protection for certain people.
"The reality in Ireland today is that we have 150,000 households, according to the last Census, based on a co-habiting couple who are not married - and 75,000 of those households have children.
"So currently there's just a gap in protection for those families.
"And I think - and in fact most people, I think now believe - that the Constitutional definition of family should be changed to make it more inclusive.
"In other words single parent families, co-habiting couples, other forms of households should also be recognised".
Asked about people who may not wish to be considered a de-facto family, or those who do not wish to marry for whatever reason, she says the next steps would determine such definitions.
"The difficulty for us as legislators is how we expand the definition of family and... that's the next part of the challenge.
"I think there's a widespread acceptance [that] we need to broaden the definition beyond family based on marriage.
"But... it's where we draw the parameters that is the challenge".
