The Supreme Court has ruled that the first marriage of a Lebanese man with two wives can be recognised under Irish law.
The decision could have implications for other polygamous marriages in Ireland.
The court held the man's second marriage is not valid under Irish law, while the first one remains in force.
However, it found that did not mean such a marriage could never have legal consequences in Ireland.
Ms Justice Iseult O'Malley said the court's conclusions were subject to the right of the Oireachtas to consider and legislate for issues of public policy in accordance with the Constitution.
Mr Justice Frank Clarke said there was a strong imperative that urgent attention be given to the question of whether or not legislation should be enacted.
The man who took the case is 64, and became an Irish citizen after securing refugee status in 2000.
He appealed to the Supreme Court against the High Court's decision that his marriage to his first wife in Lebanon could not be recognised under Irish law.
He married his first wife in 1975 and his second wife in 1988 in Lebanon.
Under Lebanese law a man can have up to four wives. He has children by both women.
His first wife came to Ireland in 2001. In 2003, he sought permission to have her enter the country but was refused.
She was permitted to come in 2004, on condition he take legal action to determine if his first marriage could be recognised under Irish law. Both wives supported his case.
The seven Supreme Court judges unanimously found in his favour.
Ms Justice O'Malley said the only bar to the recognition of the first marriage was that the system of law under which the couple married would permit more than one marriage.
She said recognition should be afforded from the date of the marriage and should not be withdrawn in the event of a second or subsequent marriage by the husband.