The first marriages for gay couples will be delayed into 2016 while the result of the same-sex marriage referendum goes through the Court of Appeal.
The government had hoped to pass the legislation before the Dáil rises in July.
But the hopes of enacting legislation by July are seriously in doubt because of two separate legal challenges to the outcome of the vote.
One is brought by Gerry Walshe, an electrician from Lisdeen Road, Co Clare - the other by Maurice Lyons, a gardener with an address at Callan, Co Kilkenny.
In the High Court, Mr Walshe claimed there was State bias in funds towards the Yes side, and he claimed the secrecy of the ballot was compromised by CCTV at polling stations.
Both cases were dismissed by High Court President Nicholas Kearns.
However an appeal hearing has been set for July 30th - two weeks after the Dáil rises - which means legislation may not be in place until at least the autumn.
Dr Fergus Ryan is a law lecturer at NUI Maynooth. He told Newstalk Breakfast if this appeal passes, it would be a first.