A four-year fight over bubbles between mobile phone operators 3 and O2 looks set to boost comparison advertising, following a European Union court opinion allowing companies to use rivals’ logos.

O2 first sued Hutchison 3G, owners of the 3 brand, in 2004 for allegedly infringing its trademarks by running television adverts that featured pictures of bubbles burbling alongside the O2 brand name. O2 argued the bubbles were part of its own distinctive brand motif, built up through a sustained – and expensive – marketing campaign.