Advocate General Mengozzi has delivered his Opinion from the UK reference in Case C-533/06 O2 Holdings v Hutchison 3G (the case concerning comparative advertising using bubbles).
... I propose that the Court give the following answer to the questions referred by the Court of Appeal (England and Wales):
(1) The use of a sign identical or similar to the registered trade mark of a competitor in an advertisement which compares the characteristics of goods or services marketed by that competitor under that trade mark with the characteristics of goods or services supplied by the advertiser is covered exhaustively by Article 3a of Council Directive 84/450/EEC of 10 September 1984 concerning misleading and comparative advertising, as amended by Directive 97/55/EC of the European Parliament and of the Council of 6 October 1997, and is not subject to the application of Article 5(1)(a) or (b) of First Council Directive 89/104/EEC of 21 December 1988 to approximate the laws of the Member States relating to trade marks.
(2) Article 3a of Directive 84/450 is not to be interpreted as permitting the use, in a comparative advertisement, of a sign identical or similar to the registered trade mark of a competitor only when that use is indispensable for the purpose of identifying the competitor or the goods or services concerned.More from the IPKat when he's had a chance to digest...