The High Court case between An Taisce and Glanbia over its proposed new cheese plant in Kilkenny kicked off this week.
On Tuesday, the judicial review began in the High Court into the decision by An Bord Pleanála to award planning permission to Glanbia to build a €150m new continental cheese plant in Belview, Co Kilkenny.
Legal submissions as part of this judicial review are expected to be completed later this week.
High Court judge Richard Humphreys will then adjourn to review the case before making his decision, which will likely take a number of months.
The proposed new continental cheese plant is to be a joint venture between Glanbia and Dutch company Royal A-ware.
The facility is a Brexit diversification investment from Glanbia as it will produce Edam and Gouda cheeses for the European market in a bid to produce more than just cheddar cheese for the UK market.
Kilkenny County Council granted planning permission for the new cheese plant in 2019.
An Taisce subsequently lodged an appeal against the decision with An Bord Pleanála in December last year.
However, An Bord Pleanála upheld the decision to grant planning permission.
An Taisce then moved to take the matter through the courts.