Watershed legislation to reform and update family law, bringing it into line “with the realities of modern Irish life”, has been introduced in the Dáil.

Minister for Justice Frances Fitzgerald said the best interests of the child was the "golden thread" running through everything in the Children and Family Relationships Bill, a long-awaited and controversial piece of legislation.

The Bill is underpinned by two key principles: that the best interests of the child “must be central” to laws on familial relationships, whatever the family type; and the implementation of the Bill should “promote the stability of such families” and “ensure that children are enabled to enjoy relationships of care and support with parents, guardians or those acting in loco parentis”.

Parentage

Ms Fitzgerald said the Bill would not change the situation of the vast majority of children or change the rights of most children in terms of parentage.

But two categories of children “will get the chance to gain a parent or parents as a result of this Bill”. A donor-conceived child will have the right to a second parent. Currently if the child is born to a female same-sex couple the child has only one legally recognised parent if the donor is unknown.

The Bill will enable a child to be jointly adopted by couples who are civil partners of each other or who have cohabited for at least three years.

There was a range of views about what was best for children, from being brought up by their natural mother and father in a marital setting to the opposite view that children should be “brought up by any parent or parents who love the child and dedicate themselves to the children’s welfare, regardless of their gender or sexual orientation”.

The Minister stressed: “Our challenge is to ensure the children’s best interests are served, regardless of the family type.”

One of the issues much commented on is the proposal to allow civil partners and cohabiting couples to adopt jointly. Ms Fitzgerald said her view, and the view underpinning the Bill, was that adoption was a child welfare mechanism.

“It is not about discriminating in favour of particular family types. It is not about the marital status of the adopters. It is about giving a child the chance to have a family. It is about matching the child to a family that best safeguards the child’s welfare,” the Minister said.

Sinn Féin justice spokesman Pádraig Mac Lochlainn challenged “attempts by some to label this Bill as the ‘gay adoption Bill’. This is a mischievous disservice to what is a pretty comprehensive overhaul of family law,” he said.

He said “single persons who are gay or lesbian have been able to adopt children for many years now, and the Children and Family Relationships Bill just ensures that in the case of same-sex relationships both parents of the child have guardianship rights and that the child has the same rights as any other.”

Fianna Fáil justice spokesman Niall Collins expressed concern at the delay in publishing the legislation, after the first general scheme of the Bill was produced in January 2014. He did not believe legislation of this importance should be published "only days in advance of second stage being taken in this House", and for all members to have gone through hundreds of pages in four days before that debate.

He described as unhelpful discussion at the same time on both the Bill and the same-sex marriage referendum.