David Walsh claims he is entitled to a one-sixth share — €564,000 — of the winning ticket, which was one of two sold in a draw with a total jackpot of €6.7m held on January 22, 2011.
One of the two winning tickets was bought for €12 at Salmons Department Store, Main St, Ballinasloe, Co Galway, entitling the winner to a €3.38m share of the total jackpot.
Mr Walsh, of Knock- nagreena, Ballinasloe, has sued his stepmother Mary Walsh, of Perssepark, Ballinasloe.
He is seeking a number of orders, including one declaring that he is entitled to €564,000 from the prize money and that Ms Walsh received the winnings as trustee for her stepson.
Ms Walsh denies the claim and says that Mr Walsh is not entitled to the money claimed.
The court heard previously Mr Walsh claims he was one of six people, in an alleged syndicate, who signed the back of the winning ticket and is entitled to a one-sixth share.
He claims Ms Walsh, and the estate of his late father Peter, who died in late 2011, holds that money in trust for him.
She says that the ticket belonged to her and not her stepson.
The case was due for hearing this week but there was a dispute over whether legal professional privilege applied to certain documents.
Mr Justice Paul Gilligan — after hearing submissions — ruled that Mr Walsh should be given an opportunity to discover 15 documents in advance of the hearing.
Mr Justice Gilligan listed the case for hearing on January 11.