Jacobs has accused rival biscuit firm McVities of "living dangerously" in a High Court row over fig rolls and cream crackers.
One hundred thousand packets of McVities biscuits are at the centre of the dispute which isn't over how they get the figs into fig rolls but about how the biscuits are packaged.
The Irish-owned Jacobs Fruitfield Food Group has accused United Biscuits, trading as McVities, of "piggy-backing" on the goodwill of Jacobs in the Irish market by packaging McVities crackers and fig rolls in a manner similar to Jacobs brands.
Jacobs wants an injunction halting the sale of 100,000 packets of McVities biscuits wrapped in the allegedly similar packaging.
Mr Justice Frank Clarke was told that 10,000 packages of the McVities biscuits are on the shelves in supermarkets with another 90,000 in warehouses awaiting the outcome of the court case.
The injunction hearing continues today when Rory Brady SC will make the case for McVities.
Mr Justice Clarke said he will give a decision tomorrow and a full judgment at a later date.
Seeking the injunction yesterday, John Gleeson SC, for Jacobs, said his client wanted to prevent McVities from selling, advertising or distributing their fig rolls and cream cracker products as they were packaged in a manner confusingly similar to those of Jacobs.
He said McVities' actions could do incalculable damage to Jacobs, which was one hundred years in the business and enjoyed 90 per cent of the market for cream crackers and fig rolls in Ireland. Jacobs employs 300 people in Tallaght, Dublin.
He said the McVities product was the same size and shape as that of Jacobs and the words fig roll appear in the centre of the packaging. The photography used in the packaging was also similar.
Because McVities markets the Jacobs brand in the UK, it had all the necessary artwork and software, including the relevant photographs used in the packaging of the products being sold in Ireland, counsel added. This had not been denied by McVities.
Mr Gleeson said this case was about a deliberate attempt to copy the Jacobs product. There could be no doubt that Jacobs had established that there was a risk of confusion. McVities had chosen a design very close to Jacobs and had decided to "live dangerously".
He said McVities had argued the design on the McVities' packaging was independently arrived at but this was vigorously contested by his clients.
There was no reason why McVities could not have adopted a different colour scheme on their packaging. If one looked at the two products, there could be no doubt that they gave rise to confusion.
While McVities had said on September 20th last that they would repackage their fig rolls and cream crackers here, that would take four weeks, counsel added. There was nothing to stop McVities from putting the 100,000 packets in new packaging, he added.