Legal counsel for both the Magnier and Thomson-Moore sides of the controversial Barne Estate case have highlighted the rate at which costs are escalating for their respective clients.

The cost of examining documents related to the case, known as discovery, have already exceeded €1m for the defendants Richard Thomson-Moore, Barne Estate Ltd and two Jersey-registered companies - IQ EQ One and IQ EQ Two - the High Court was told on Thursday.

Senior counsel Martin Hayden, acting for the Barne side, accused the plaintiffs John Magnier, John Paul Magnier and Katherine Wachman of attempting to run a “rolling enquiry which changes as the case develops”.

This was vehemently disputed by his legal opponent, senior counsel Paul Gallagher, who told the court they were entitled to examine and question relevant aspects of the case and documents.

'Immense' costs

Martin Hayden told the court that costs of €300,000 to €400,000 were attached to just one aspect of the discovery process and that the discovery process overall was costing his clients over €1m.

Mr Gallagher also told the court that the cost of discovery to his clients, the Magnier family, would be “immense”.

He criticised the need for the defendants, the Barne side, to draft in a consulting IT expert to look at relatively recent transactions.

Amid an afternoon of legal argument between the two sides, the court heard that an eight-week search of documents in Jersey required the establishment of a forensic lab on the island, the use of forensic imaging and the examination of five laptops and 170 sharepoints.

The eight-week search resulted in 17.7m documents and over 10m terabytes of source data being examined.

Thursday was day six of the hearing into the contested sale of Barne Estate in Co Tipperary. John Magnier, his son John Paul and daughter Katherine Wachman, took the case against Richard Thomson-Moore, Barne Estate Ltd, and two Jersey-registered companies - IQ EQ One and IQ EQ Two.

The Magniers allege that the Barne side broke a binding deal to sell the 751ac estate to him for €15m in August 2023 and broke an exclusivity agreement by agreeing to sell the estate to construction magnate Maurice Regan.

Mr Regan agreed to pay €22.25m for the estate, some €7.5m more than Magnier’s alleged deal at €15m.

The case continues under Mr Justice Max Barrett.