DUNNES Stores engaged in a misleading commercial practice likely to deceive customers in an advertising comparison campaign for certain products with rival Aldi, the High Court has ruled.
Dunnes had infringed consumer protection law and EU regulations in its campaign, Mr Justice Brian Cregan said.
He was giving judgment in an application by Aldi for an injunction preventing Dunnes infringing its trademarks.
He will hear submissions in two weeks' time from both sides on what orders he should make.
Aldi is also seeking damages while Dunnes is to consider whether to seek a stay on the judge's decision in the event of an appeal.
Aldi had claimed that in 2013 Dunnes infringed its trademarks through the use of in-store shelf labelling and through the use of free-standing shop-floor advertising "banners" claiming Dunnes' prices were cheaper. Dunnes denied the claims and said the advertisements were lawful.
Mr Justice Cregan found that in relation to pricing labels on Dunnes shelves on 14 out of 15 products, the company had infringed the regulations and Irish law by not giving customers enough information.
In a Dunnes advertisement for pork sausages, for example, it did not draw any attention to the fact that the Aldi product had a Bord Bia approval logo which is an indicator of provenance and quality, he said.
Other examples were that the Aldi toilet tissue was heavier and longer while a yogurt contained 13pc more strawberry than the Dunnes' product.
He also found Dunnes had taken unfair advantage of the Aldi trademarks.